diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index d95001b104106..36fbbeb2ec74b 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -158,7 +158,7 @@ namespace ts {
          * If so, the node _must_ be in the current file (as that's the only way anything could have traversed to it to yield it as the error node)
          * This version of `createDiagnosticForNode` uses the binder's context to account for this, and always yields correct diagnostics even in these situations.
          */
-        function createDiagnosticForNode(node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number): Diagnostic {
+        function createDiagnosticForNode(node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number): DiagnosticWithLocation {
             return createDiagnosticForNodeInSourceFile(getSourceFileOfNode(node) || file, node, message, arg0, arg1, arg2);
         }
 
@@ -1208,7 +1208,7 @@ namespace ts {
             bind(node.statement);
             popActiveLabel();
             if (!activeLabel.referenced && !options.allowUnusedLabels) {
-                file.bindDiagnostics.push(createDiagnosticForNode(node.label, Diagnostics.Unused_label));
+                errorOrSuggestionOnFirstToken(unusedLabelIsError(options), node, Diagnostics.Unused_label);
             }
             if (!node.statement || node.statement.kind !== SyntaxKind.DoStatement) {
                 // do statement sets current flow inside bindDoStatement
@@ -1914,6 +1914,17 @@ namespace ts {
             file.bindDiagnostics.push(createFileDiagnostic(file, span.start, span.length, message, arg0, arg1, arg2));
         }
 
+        function errorOrSuggestionOnFirstToken(isError: boolean, node: Node, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any) {
+            const span = getSpanOfTokenAtPosition(file, node.pos);
+            const diag = createFileDiagnostic(file, span.start, span.length, message, arg0, arg1, arg2);
+            if (isError) {
+                file.bindDiagnostics.push(diag);
+            }
+            else {
+                file.bindSuggestionDiagnostics = append(file.bindSuggestionDiagnostics, { ...diag, category: DiagnosticCategory.Suggestion });
+            }
+        }
+
         function bind(node: Node): void {
             if (!node) {
                 return;
@@ -2730,26 +2741,26 @@ namespace ts {
                 if (reportError) {
                     currentFlow = reportedUnreachableFlow;
 
-                    // unreachable code is reported if
-                    // - user has explicitly asked about it AND
-                    // - statement is in not ambient context (statements in ambient context is already an error
-                    //   so we should not report extras) AND
-                    //   - node is not variable statement OR
-                    //   - node is block scoped variable statement OR
-                    //   - node is not block scoped variable statement and at least one variable declaration has initializer
-                    //   Rationale: we don't want to report errors on non-initialized var's since they are hoisted
-                    //   On the other side we do want to report errors on non-initialized 'lets' because of TDZ
-                    const reportUnreachableCode =
-                        !options.allowUnreachableCode &&
-                        !(node.flags & NodeFlags.Ambient) &&
-                        (
-                            node.kind !== SyntaxKind.VariableStatement ||
-                            getCombinedNodeFlags((<VariableStatement>node).declarationList) & NodeFlags.BlockScoped ||
-                            forEach((<VariableStatement>node).declarationList.declarations, d => d.initializer)
-                        );
-
-                    if (reportUnreachableCode) {
-                        errorOnFirstToken(node, Diagnostics.Unreachable_code_detected);
+                    if (!options.allowUnreachableCode) {
+                        // unreachable code is reported if
+                        // - user has explicitly asked about it AND
+                        // - statement is in not ambient context (statements in ambient context is already an error
+                        //   so we should not report extras) AND
+                        //   - node is not variable statement OR
+                        //   - node is block scoped variable statement OR
+                        //   - node is not block scoped variable statement and at least one variable declaration has initializer
+                        //   Rationale: we don't want to report errors on non-initialized var's since they are hoisted
+                        //   On the other side we do want to report errors on non-initialized 'lets' because of TDZ
+                        const isError =
+                            unreachableCodeIsError(options) &&
+                            !(node.flags & NodeFlags.Ambient) &&
+                            (
+                                !isVariableStatement(node) ||
+                                !!(getCombinedNodeFlags(node.declarationList) & NodeFlags.BlockScoped) ||
+                                node.declarationList.declarations.some(d => !!d.initializer)
+                            );
+
+                        errorOrSuggestionOnFirstToken(isError, node, Diagnostics.Unreachable_code_detected);
                     }
                 }
             }
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 748ff9784342e..53d7ce23a999f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -313,11 +313,11 @@ namespace ts {
 
             getSuggestionDiagnostics: file => {
                 return (suggestionDiagnostics.get(file.fileName) || emptyArray).concat(getUnusedDiagnostics());
-                function getUnusedDiagnostics(): ReadonlyArray<Diagnostic> {
+                function getUnusedDiagnostics(): ReadonlyArray<DiagnosticWithLocation> {
                     if (file.isDeclarationFile) return emptyArray;
 
                     checkSourceFile(file);
-                    const diagnostics: Diagnostic[] = [];
+                    const diagnostics: DiagnosticWithLocation[] = [];
                     Debug.assert(!!(getNodeLinks(file).flags & NodeCheckFlags.TypeChecked));
                     checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(file), (kind, diag) => {
                         if (!unusedIsError(kind)) {
@@ -481,7 +481,7 @@ namespace ts {
 
         const diagnostics = createDiagnosticCollection();
         // Suggestion diagnostics must have a file. Keyed by source file name.
-        const suggestionDiagnostics = createMultiMap<Diagnostic>();
+        const suggestionDiagnostics = createMultiMap<DiagnosticWithLocation>();
 
         const enum TypeFacts {
             None = 0,
@@ -628,7 +628,7 @@ namespace ts {
             Local,
             Parameter,
         }
-        type AddUnusedDiagnostic = (type: UnusedKind, diagnostic: Diagnostic) => void;
+        type AddUnusedDiagnostic = (type: UnusedKind, diagnostic: DiagnosticWithLocation) => void;
 
         const builtinGlobals = createSymbolTable();
         builtinGlobals.set(undefinedSymbol.escapedName, undefinedSymbol);
@@ -824,7 +824,7 @@ namespace ts {
             diagnostics.add(diagnostic);
         }
 
-        function addErrorOrSuggestion(isError: boolean, diagnostic: Diagnostic) {
+        function addErrorOrSuggestion(isError: boolean, diagnostic: DiagnosticWithLocation) {
             if (isError) {
                 diagnostics.add(diagnostic);
             }
@@ -9286,8 +9286,10 @@ namespace ts {
             return type;
         }
 
-        function getRegularTypeOfLiteralType(type: Type) {
-            return type.flags & TypeFlags.StringOrNumberLiteral && type.flags & TypeFlags.FreshLiteral ? (<LiteralType>type).regularType : type;
+        function getRegularTypeOfLiteralType(type: Type): Type {
+            return type.flags & TypeFlags.StringOrNumberLiteral && type.flags & TypeFlags.FreshLiteral ? (<LiteralType>type).regularType :
+                type.flags & TypeFlags.Union ? getUnionType(sameMap((<UnionType>type).types, getRegularTypeOfLiteralType)) :
+                type;
         }
 
         function getLiteralType(value: string | number, enumId?: number, symbol?: Symbol) {
@@ -12774,10 +12776,12 @@ namespace ts {
             // all inferences were made to top-level occurrences of the type parameter, and
             // the type parameter has no constraint or its constraint includes no primitive or literal types, and
             // the type parameter was fixed during inference or does not occur at top-level in the return type.
-            const widenLiteralTypes = inference.topLevel &&
-                !hasPrimitiveConstraint(inference.typeParameter) &&
+            const primitiveConstraint = hasPrimitiveConstraint(inference.typeParameter);
+            const widenLiteralTypes = !primitiveConstraint && inference.topLevel &&
                 (inference.isFixed || !isTypeParameterAtTopLevel(getReturnTypeOfSignature(signature), inference.typeParameter));
-            const baseCandidates = widenLiteralTypes ? sameMap(candidates, getWidenedLiteralType) : candidates;
+            const baseCandidates = primitiveConstraint ? sameMap(candidates, getRegularTypeOfLiteralType) :
+                widenLiteralTypes ? sameMap(candidates, getWidenedLiteralType) :
+                candidates;
             // If all inferences were made from contravariant positions, infer a common subtype. Otherwise, if
             // union types were requested or if all inferences were made from the return type position, infer a
             // union type. Otherwise, infer a common supertype.
@@ -15303,6 +15307,26 @@ namespace ts {
             }
         }
 
+        // Return true if the given expression is possibly a discriminant value. We limit the kinds of
+        // expressions we check to those that don't depend on their contextual type in order not to cause
+        // recursive (and possibly infinite) invocations of getContextualType.
+        function isPossiblyDiscriminantValue(node: Expression): boolean {
+            switch (node.kind) {
+                case SyntaxKind.StringLiteral:
+                case SyntaxKind.NumericLiteral:
+                case SyntaxKind.NoSubstitutionTemplateLiteral:
+                case SyntaxKind.TrueKeyword:
+                case SyntaxKind.FalseKeyword:
+                case SyntaxKind.NullKeyword:
+                case SyntaxKind.Identifier:
+                    return true;
+                case SyntaxKind.PropertyAccessExpression:
+                case SyntaxKind.ParenthesizedExpression:
+                    return isPossiblyDiscriminantValue((<PropertyAccessExpression | ParenthesizedExpression>node).expression);
+            }
+            return false;
+        }
+
         // Return the contextual type for a given expression node. During overload resolution, a contextual type may temporarily
         // be "pushed" onto a node using the contextualType property.
         function getApparentTypeOfContextualType(node: Expression): Type {
@@ -15316,8 +15340,8 @@ namespace ts {
             propLoop: for (const prop of node.properties) {
                 if (!prop.symbol) continue;
                 if (prop.kind !== SyntaxKind.PropertyAssignment) continue;
-                if (isDiscriminantProperty(contextualType, prop.symbol.escapedName)) {
-                    const discriminatingType = getTypeOfNode(prop.initializer);
+                if (isPossiblyDiscriminantValue(prop.initializer) && isDiscriminantProperty(contextualType, prop.symbol.escapedName)) {
+                    const discriminatingType = checkExpression(prop.initializer);
                     for (const type of (contextualType as UnionType).types) {
                         const targetType = getTypeOfPropertyOfType(type, prop.symbol.escapedName);
                         if (targetType && checkTypeAssignableTo(discriminatingType, targetType, /*errorNode*/ undefined)) {
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 81ae60f70e738..536e42cd59ad2 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -14,8 +14,8 @@ namespace ts {
         return pathIsRelative(moduleName) || isRootedDiskPath(moduleName);
     }
 
-    export function sortAndDeduplicateDiagnostics(diagnostics: ReadonlyArray<Diagnostic>): Diagnostic[] {
-        return sortAndDeduplicate(diagnostics, compareDiagnostics);
+    export function sortAndDeduplicateDiagnostics<T extends Diagnostic>(diagnostics: ReadonlyArray<T>): T[] {
+        return sortAndDeduplicate<T>(diagnostics, compareDiagnostics);
     }
 }
 
@@ -1619,8 +1619,8 @@ namespace ts {
         return localizedDiagnosticMessages && localizedDiagnosticMessages[message.key] || message.message;
     }
 
-    export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage, ...args: (string | number)[]): Diagnostic;
-    export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage): Diagnostic {
+    export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage, ...args: (string | number)[]): DiagnosticWithLocation;
+    export function createFileDiagnostic(file: SourceFile, start: number, length: number, message: DiagnosticMessage): DiagnosticWithLocation {
         Debug.assertGreaterThanOrEqual(start, 0);
         Debug.assertGreaterThanOrEqual(length, 0);
 
@@ -1991,6 +1991,14 @@ namespace ts {
         return moduleResolution;
     }
 
+    export function unreachableCodeIsError(options: CompilerOptions): boolean {
+        return options.allowUnreachableCode === false;
+    }
+
+    export function unusedLabelIsError(options: CompilerOptions): boolean {
+        return options.allowUnusedLabels === false;
+    }
+
     export function getAreDeclarationMapsEnabled(options: CompilerOptions) {
         return !!(options.declaration && options.declarationMap);
     }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 761e89ae64566..59007e610b4ad 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -2238,7 +2238,8 @@
     },
     "Left side of comma operator is unused and has no side effects.": {
         "category": "Error",
-        "code": 2695
+        "code": 2695,
+        "reportsUnnecessary": true
     },
     "The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?": {
         "category": "Error",
@@ -3673,7 +3674,8 @@
     },
     "Unreachable code detected.": {
         "category": "Error",
-        "code": 7027
+        "code": 7027,
+        "reportsUnnecessary": true
     },
     "Unused label.": {
         "category": "Error",
diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index a286c9fae3566..489bc72db621f 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -2463,6 +2463,7 @@ namespace ts {
             if (node.symbolCount !== undefined) updated.symbolCount = node.symbolCount;
             if (node.parseDiagnostics !== undefined) updated.parseDiagnostics = node.parseDiagnostics;
             if (node.bindDiagnostics !== undefined) updated.bindDiagnostics = node.bindDiagnostics;
+            if (node.bindSuggestionDiagnostics !== undefined) updated.bindSuggestionDiagnostics = node.bindSuggestionDiagnostics;
             if (node.lineMap !== undefined) updated.lineMap = node.lineMap;
             if (node.classifiableNames !== undefined) updated.classifiableNames = node.classifiableNames;
             if (node.resolvedModules !== undefined) updated.resolvedModules = node.resolvedModules;
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 3a7adbc260915..975331e715366 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -595,7 +595,7 @@ namespace ts {
         // tslint:enable variable-name
 
         let sourceFile: SourceFile;
-        let parseDiagnostics: Diagnostic[];
+        let parseDiagnostics: DiagnosticWithLocation[];
         let syntaxCursor: IncrementalParser.SyntaxCursor;
 
         let currentToken: SyntaxKind;
@@ -912,6 +912,7 @@ namespace ts {
 
             sourceFile.text = sourceText;
             sourceFile.bindDiagnostics = [];
+            sourceFile.bindSuggestionDiagnostics = undefined;
             sourceFile.languageVersion = languageVersion;
             sourceFile.fileName = normalizePath(fileName);
             sourceFile.languageVariant = getLanguageVariant(scriptKind);
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 365e948f749e4..c453080f3bf9b 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -394,8 +394,8 @@ namespace ts {
         return resolutions;
     }
 
-    interface DiagnosticCache {
-        perFile?: Map<Diagnostic[]>;
+    interface DiagnosticCache<T extends Diagnostic> {
+        perFile?: Map<T[]>;
         allDiagnostics?: Diagnostic[];
     }
 
@@ -454,7 +454,7 @@ namespace ts {
 
     export function getConfigFileParsingDiagnostics(configFileParseResult: ParsedCommandLine): ReadonlyArray<Diagnostic> {
         return configFileParseResult.options.configFile ?
-            configFileParseResult.options.configFile.parseDiagnostics.concat(configFileParseResult.errors) :
+            [...configFileParseResult.options.configFile.parseDiagnostics, ...configFileParseResult.errors] :
             configFileParseResult.errors;
     }
 
@@ -517,8 +517,8 @@ namespace ts {
         let classifiableNames: UnderscoreEscapedMap<true>;
         let modifiedFilePaths: Path[] | undefined;
 
-        const cachedSemanticDiagnosticsForFile: DiagnosticCache = {};
-        const cachedDeclarationDiagnosticsForFile: DiagnosticCache = {};
+        const cachedSemanticDiagnosticsForFile: DiagnosticCache<Diagnostic> = {};
+        const cachedDeclarationDiagnosticsForFile: DiagnosticCache<DiagnosticWithLocation> = {};
 
         let resolvedTypeReferenceDirectives = createMap<ResolvedTypeReferenceDirective>();
         let fileProcessingDiagnostics = createDiagnosticCollection();
@@ -1313,10 +1313,10 @@ namespace ts {
             return filesByName.get(path);
         }
 
-        function getDiagnosticsHelper(
+        function getDiagnosticsHelper<T extends Diagnostic>(
             sourceFile: SourceFile,
-            getDiagnostics: (sourceFile: SourceFile, cancellationToken: CancellationToken) => ReadonlyArray<Diagnostic>,
-            cancellationToken: CancellationToken): ReadonlyArray<Diagnostic> {
+            getDiagnostics: (sourceFile: SourceFile, cancellationToken: CancellationToken) => ReadonlyArray<T>,
+            cancellationToken: CancellationToken): ReadonlyArray<T> {
             if (sourceFile) {
                 return getDiagnostics(sourceFile, cancellationToken);
             }
@@ -1328,7 +1328,7 @@ namespace ts {
             }));
         }
 
-        function getSyntacticDiagnostics(sourceFile: SourceFile, cancellationToken: CancellationToken): ReadonlyArray<Diagnostic> {
+        function getSyntacticDiagnostics(sourceFile: SourceFile, cancellationToken: CancellationToken): ReadonlyArray<DiagnosticWithLocation> {
             return getDiagnosticsHelper(sourceFile, getSyntacticDiagnosticsForFile, cancellationToken);
         }
 
@@ -1336,7 +1336,7 @@ namespace ts {
             return getDiagnosticsHelper(sourceFile, getSemanticDiagnosticsForFile, cancellationToken);
         }
 
-        function getDeclarationDiagnostics(sourceFile: SourceFile, cancellationToken: CancellationToken): ReadonlyArray<Diagnostic> {
+        function getDeclarationDiagnostics(sourceFile: SourceFile, cancellationToken: CancellationToken): ReadonlyArray<DiagnosticWithLocation> {
             const options = program.getCompilerOptions();
             // collect diagnostics from the program only once if either no source file was specified or out/outFile is set (bundled emit)
             if (!sourceFile || options.out || options.outFile) {
@@ -1347,7 +1347,7 @@ namespace ts {
             }
         }
 
-        function getSyntacticDiagnosticsForFile(sourceFile: SourceFile): ReadonlyArray<Diagnostic> {
+        function getSyntacticDiagnosticsForFile(sourceFile: SourceFile): ReadonlyArray<DiagnosticWithLocation> {
             // For JavaScript files, we report semantic errors for using TypeScript-only
             // constructs from within a JavaScript file as syntactic errors.
             if (isSourceFileJavaScript(sourceFile)) {
@@ -1382,7 +1382,7 @@ namespace ts {
             }
         }
 
-        function getSemanticDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
+        function getSemanticDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): ReadonlyArray<Diagnostic> {
             return getAndCacheDiagnostics(sourceFile, cancellationToken, cachedSemanticDiagnosticsForFile, getSemanticDiagnosticsForFileNoCache);
         }
 
@@ -1403,15 +1403,22 @@ namespace ts {
                 // By default, only type-check .ts, .tsx, 'Deferred' and 'External' files (external files are added by plugins)
                 const includeBindAndCheckDiagnostics = sourceFile.scriptKind === ScriptKind.TS || sourceFile.scriptKind === ScriptKind.TSX ||
                     sourceFile.scriptKind === ScriptKind.External || isCheckJs || sourceFile.scriptKind === ScriptKind.Deferred;
-                const bindDiagnostics = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
+                const bindDiagnostics: ReadonlyArray<Diagnostic> = includeBindAndCheckDiagnostics ? sourceFile.bindDiagnostics : emptyArray;
                 const checkDiagnostics = includeBindAndCheckDiagnostics ? typeChecker.getDiagnostics(sourceFile, cancellationToken) : emptyArray;
                 const fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 const programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
-                let diagnostics = bindDiagnostics.concat(checkDiagnostics, fileProcessingDiagnosticsInFile, programDiagnosticsInFile);
-                if (isCheckJs) {
-                    diagnostics = concatenate(diagnostics, sourceFile.jsDocDiagnostics);
+
+                let diagnostics: Diagnostic[] | undefined;
+                for (const diags of [bindDiagnostics, checkDiagnostics, fileProcessingDiagnosticsInFile, programDiagnosticsInFile, isCheckJs ? sourceFile.jsDocDiagnostics : undefined]) {
+                    if (diags) {
+                        for (const diag of diags) {
+                            if (shouldReportDiagnostic(diag)) {
+                                diagnostics = append(diagnostics, diag);
+                            }
+                        }
+                    }
                 }
-                return filter(diagnostics, shouldReportDiagnostic);
+                return diagnostics;
             });
         }
 
@@ -1440,9 +1447,9 @@ namespace ts {
             return true;
         }
 
-        function getJavaScriptSyntacticDiagnosticsForFile(sourceFile: SourceFile): Diagnostic[] {
+        function getJavaScriptSyntacticDiagnosticsForFile(sourceFile: SourceFile): DiagnosticWithLocation[] {
             return runWithCancellationToken(() => {
-                const diagnostics: Diagnostic[] = [];
+                const diagnostics: DiagnosticWithLocation[] = [];
                 let parent: Node = sourceFile;
                 walk(sourceFile);
 
@@ -1610,20 +1617,20 @@ namespace ts {
                     }
                 }
 
-                function createDiagnosticForNodeArray(nodes: NodeArray<Node>, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number): Diagnostic {
+                function createDiagnosticForNodeArray(nodes: NodeArray<Node>, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number): DiagnosticWithLocation {
                     const start = nodes.pos;
                     return createFileDiagnostic(sourceFile, start, nodes.end - start, message, arg0, arg1, arg2);
                 }
 
                 // Since these are syntactic diagnostics, parent might not have been set
                 // this means the sourceFile cannot be infered from the node
-                function createDiagnosticForNode(node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number): Diagnostic {
+                function createDiagnosticForNode(node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number): DiagnosticWithLocation {
                     return createDiagnosticForNodeInSourceFile(sourceFile, node, message, arg0, arg1, arg2);
                 }
             });
         }
 
-        function getDeclarationDiagnosticsWorker(sourceFile: SourceFile | undefined, cancellationToken: CancellationToken): Diagnostic[] {
+        function getDeclarationDiagnosticsWorker(sourceFile: SourceFile, cancellationToken: CancellationToken): ReadonlyArray<DiagnosticWithLocation> {
             return getAndCacheDiagnostics(sourceFile, cancellationToken, cachedDeclarationDiagnosticsForFile, getDeclarationDiagnosticsForFileNoCache);
         }
 
@@ -1635,15 +1642,16 @@ namespace ts {
             });
         }
 
-        function getAndCacheDiagnostics(
+        function getAndCacheDiagnostics<T extends Diagnostic>(
             sourceFile: SourceFile | undefined,
             cancellationToken: CancellationToken,
-            cache: DiagnosticCache,
-            getDiagnostics: (sourceFile: SourceFile, cancellationToken: CancellationToken) => Diagnostic[]) {
+            cache: DiagnosticCache<T>,
+            getDiagnostics: (sourceFile: SourceFile, cancellationToken: CancellationToken) => T[],
+        ): ReadonlyArray<T> {
 
             const cachedResult = sourceFile
                 ? cache.perFile && cache.perFile.get(sourceFile.path)
-                : cache.allDiagnostics;
+                : cache.allDiagnostics as T[];
 
             if (cachedResult) {
                 return cachedResult;
@@ -1651,7 +1659,7 @@ namespace ts {
             const result = getDiagnostics(sourceFile, cancellationToken) || emptyArray;
             if (sourceFile) {
                 if (!cache.perFile) {
-                    cache.perFile = createMap<Diagnostic[]>();
+                    cache.perFile = createMap<T[]>();
                 }
                 cache.perFile.set(sourceFile.path, result);
             }
@@ -1661,7 +1669,7 @@ namespace ts {
             return result;
         }
 
-        function getDeclarationDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
+        function getDeclarationDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): ReadonlyArray<DiagnosticWithLocation> {
             return sourceFile.isDeclarationFile ? [] : getDeclarationDiagnosticsWorker(sourceFile, cancellationToken);
         }
 
diff --git a/src/compiler/transformer.ts b/src/compiler/transformer.ts
index 16a6912757f40..b661120b961a6 100644
--- a/src/compiler/transformer.ts
+++ b/src/compiler/transformer.ts
@@ -90,7 +90,7 @@ namespace ts {
         let onSubstituteNode: TransformationContext["onSubstituteNode"] = (_, node) => node;
         let onEmitNode: TransformationContext["onEmitNode"] = (hint, node, callback) => callback(hint, node);
         let state = TransformationState.Uninitialized;
-        const diagnostics: Diagnostic[] = [];
+        const diagnostics: DiagnosticWithLocation[] = [];
 
         // The transformation context is provided to each transformer as part of transformer
         // initialization.
diff --git a/src/compiler/transformers/declarations.ts b/src/compiler/transformers/declarations.ts
index 346f1343fabce..953f8279def76 100644
--- a/src/compiler/transformers/declarations.ts
+++ b/src/compiler/transformers/declarations.ts
@@ -1,6 +1,6 @@
 /*@internal*/
 namespace ts {
-    export function getDeclarationDiagnostics(host: EmitHost, resolver: EmitResolver, file: SourceFile | undefined): Diagnostic[] {
+    export function getDeclarationDiagnostics(host: EmitHost, resolver: EmitResolver, file: SourceFile | undefined): DiagnosticWithLocation[] {
         if (file && isSourceFileJavaScript(file)) {
             return []; // No declaration diagnostics for js for now
         }
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 19e526ba056fb..44c5ddb5d5034 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2599,16 +2599,17 @@ namespace ts {
 
         // File-level diagnostics reported by the parser (includes diagnostics about /// references
         // as well as code diagnostics).
-        /* @internal */ parseDiagnostics: Diagnostic[];
+        /* @internal */ parseDiagnostics: DiagnosticWithLocation[];
 
         // File-level diagnostics reported by the binder.
-        /* @internal */ bindDiagnostics: Diagnostic[];
+        /* @internal */ bindDiagnostics: DiagnosticWithLocation[];
+        /* @internal */ bindSuggestionDiagnostics?: DiagnosticWithLocation[];
 
         // File-level JSDoc diagnostics reported by the JSDoc parser
-        /* @internal */ jsDocDiagnostics?: Diagnostic[];
+        /* @internal */ jsDocDiagnostics?: DiagnosticWithLocation[];
 
         // Stores additional file-level diagnostics reported by the program
-        /* @internal */ additionalSyntacticDiagnostics?: ReadonlyArray<Diagnostic>;
+        /* @internal */ additionalSyntacticDiagnostics?: ReadonlyArray<DiagnosticWithLocation>;
 
         // Stores a line map for the file.
         // This field should never be used directly to obtain line map, use getLineMap function instead.
@@ -2746,9 +2747,10 @@ namespace ts {
 
         getOptionsDiagnostics(cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
         getGlobalDiagnostics(cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
-        getSyntacticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
+        getSyntacticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<DiagnosticWithLocation>;
+        /** The first time this is called, it will return global diagnostics (no location). */
         getSemanticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
-        getDeclarationDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
+        getDeclarationDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<DiagnosticWithLocation>;
         getConfigFileParsingDiagnostics(): ReadonlyArray<Diagnostic>;
 
         /**
@@ -3069,7 +3071,7 @@ namespace ts {
          * Does *not* get *all* suggestion diagnostics, just the ones that were convenient to report in the checker.
          * Others are added in computeSuggestionDiagnostics.
          */
-        /* @internal */ getSuggestionDiagnostics(file: SourceFile): ReadonlyArray<Diagnostic>;
+        /* @internal */ getSuggestionDiagnostics(file: SourceFile): ReadonlyArray<DiagnosticWithLocation>;
 
         /**
          * Depending on the operation performed, it may be appropriate to throw away the checker
@@ -4227,6 +4229,11 @@ namespace ts {
         code: number;
         source?: string;
     }
+    export interface DiagnosticWithLocation extends Diagnostic {
+        file: SourceFile;
+        start: number;
+        length: number;
+    }
 
     export enum DiagnosticCategory {
         Warning,
@@ -5083,7 +5090,7 @@ namespace ts {
          */
         onEmitNode: (hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void) => void;
 
-        /* @internal */ addDiagnostic(diag: Diagnostic): void;
+        /* @internal */ addDiagnostic(diag: DiagnosticWithLocation): void;
     }
 
     export interface TransformationResult<T extends Node> {
@@ -5091,7 +5098,7 @@ namespace ts {
         transformed: T[];
 
         /** Gets diagnostics for the transformation. */
-        diagnostics?: Diagnostic[];
+        diagnostics?: DiagnosticWithLocation[];
 
         /**
          * Gets a substitute for a node, if one is available; otherwise, returns the original node.
@@ -5309,7 +5316,8 @@ namespace ts {
 
         // If fileName is provided, gets all the diagnostics associated with that file name.
         // Otherwise, returns all the diagnostics (global and file associated) in this collection.
-        getDiagnostics(fileName?: string): Diagnostic[];
+        getDiagnostics(fileName: string): DiagnosticWithLocation[];
+        getDiagnostics(): Diagnostic[];
 
         reattachFileDiagnostics(newFile: SourceFile): void;
     }
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index df19a8948c722..64996153d23b6 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -603,7 +603,7 @@ namespace ts {
         }
     }
 
-    export function createDiagnosticForNode(node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): Diagnostic {
+    export function createDiagnosticForNode(node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): DiagnosticWithLocation {
         const sourceFile = getSourceFileOfNode(node);
         return createDiagnosticForNodeInSourceFile(sourceFile, node, message, arg0, arg1, arg2, arg3);
     }
@@ -613,17 +613,17 @@ namespace ts {
         return createFileDiagnostic(sourceFile, start, nodes.end - start, message, arg0, arg1, arg2, arg3);
     }
 
-    export function createDiagnosticForNodeInSourceFile(sourceFile: SourceFile, node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): Diagnostic {
+    export function createDiagnosticForNodeInSourceFile(sourceFile: SourceFile, node: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): DiagnosticWithLocation {
         const span = getErrorSpanForNode(sourceFile, node);
         return createFileDiagnostic(sourceFile, span.start, span.length, message, arg0, arg1, arg2, arg3);
     }
 
-    export function createDiagnosticForNodeSpan(sourceFile: SourceFile, startNode: Node, endNode: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): Diagnostic {
+    export function createDiagnosticForNodeSpan(sourceFile: SourceFile, startNode: Node, endNode: Node, message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): DiagnosticWithLocation {
         const start = skipTrivia(sourceFile.text, startNode.pos);
         return createFileDiagnostic(sourceFile, start, endNode.end - start, message, arg0, arg1, arg2, arg3);
     }
 
-    export function createDiagnosticForNodeFromMessageChain(node: Node, messageChain: DiagnosticMessageChain): Diagnostic {
+    export function createDiagnosticForNodeFromMessageChain(node: Node, messageChain: DiagnosticMessageChain): DiagnosticWithLocation {
         const sourceFile = getSourceFileOfNode(node);
         const span = getErrorSpanForNode(sourceFile, node);
         return {
@@ -2645,7 +2645,7 @@ namespace ts {
     export function createDiagnosticCollection(): DiagnosticCollection {
         let nonFileDiagnostics = [] as SortedArray<Diagnostic>;
         const filesWithDiagnostics = [] as SortedArray<string>;
-        const fileDiagnostics = createMap<SortedArray<Diagnostic>>();
+        const fileDiagnostics = createMap<SortedArray<DiagnosticWithLocation>>();
         let hasReadNonFileDiagnostics = false;
 
         return {
@@ -2664,8 +2664,8 @@ namespace ts {
             if (diagnostic.file) {
                 diagnostics = fileDiagnostics.get(diagnostic.file.fileName);
                 if (!diagnostics) {
-                    diagnostics = [] as SortedArray<Diagnostic>;
-                    fileDiagnostics.set(diagnostic.file.fileName, diagnostics);
+                    diagnostics = [] as SortedArray<DiagnosticWithLocation>;
+                    fileDiagnostics.set(diagnostic.file.fileName, diagnostics as SortedArray<DiagnosticWithLocation>);
                     insertSorted(filesWithDiagnostics, diagnostic.file.fileName, compareStringsCaseSensitive);
                 }
             }
@@ -2687,12 +2687,14 @@ namespace ts {
             return nonFileDiagnostics;
         }
 
+        function getDiagnostics(fileName: string): DiagnosticWithLocation[];
+        function getDiagnostics(): Diagnostic[];
         function getDiagnostics(fileName?: string): Diagnostic[] {
             if (fileName) {
                 return fileDiagnostics.get(fileName) || [];
             }
 
-            const fileDiags = flatMap(filesWithDiagnostics, f => fileDiagnostics.get(f));
+            const fileDiags: Diagnostic[] = flatMap(filesWithDiagnostics, f => fileDiagnostics.get(f));
             if (!nonFileDiagnostics.length) {
                 return fileDiags;
             }
diff --git a/src/harness/fourslash.ts b/src/harness/fourslash.ts
index 47f0a91b286d0..46df7fc09807c 100644
--- a/src/harness/fourslash.ts
+++ b/src/harness/fourslash.ts
@@ -1317,8 +1317,13 @@ Actual: ${stringify(fullActual)}`);
         }
 
         private testDiagnostics(expected: ReadonlyArray<FourSlashInterface.Diagnostic>, diagnostics: ReadonlyArray<ts.Diagnostic>, category: string) {
-            assert.deepEqual(ts.realizeDiagnostics(diagnostics, ts.newLineCharacter), expected.map<ts.RealizedDiagnostic>(e => (
-                { message: e.message, category, code: e.code, ...ts.createTextSpanFromRange(e.range || this.getRanges()[0]) })));
+            assert.deepEqual(ts.realizeDiagnostics(diagnostics, ts.newLineCharacter), expected.map((e): ts.RealizedDiagnostic => ({
+                message: e.message,
+                category,
+                code: e.code,
+                ...ts.createTextSpanFromRange(e.range || this.getRanges()[0]),
+                reportsUnnecessary: e.reportsUnnecessary,
+            })));
         }
 
         public verifyQuickInfoAt(markerName: string, expectedText: string, expectedDocumentation?: string) {
@@ -4422,15 +4427,15 @@ namespace FourSlashInterface {
             this.state.verifyQuickInfoDisplayParts(kind, kindModifiers, textSpan, displayParts, documentation, tags);
         }
 
-        public getSyntacticDiagnostics(expected: ReadonlyArray<ts.RealizedDiagnostic>) {
+        public getSyntacticDiagnostics(expected: ReadonlyArray<Diagnostic>) {
             this.state.getSyntacticDiagnostics(expected);
         }
 
-        public getSemanticDiagnostics(expected: ReadonlyArray<ts.RealizedDiagnostic>) {
+        public getSemanticDiagnostics(expected: ReadonlyArray<Diagnostic>) {
             this.state.getSemanticDiagnostics(expected);
         }
 
-        public getSuggestionDiagnostics(expected: ReadonlyArray<ts.RealizedDiagnostic>) {
+        public getSuggestionDiagnostics(expected: ReadonlyArray<Diagnostic>) {
             this.state.getSuggestionDiagnostics(expected);
         }
 
@@ -4837,6 +4842,7 @@ namespace FourSlashInterface {
         message: string;
         range?: FourSlash.Range;
         code: number;
+        reportsUnnecessary?: true;
     }
 
     export interface GetEditsForFileRenameOptions {
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index 28233b797da47..96d7a01eaae68 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -1406,7 +1406,7 @@ namespace Harness {
             const dupeCase = ts.createMap<number>();
             for (const inputFile of inputFiles.filter(f => f.content !== undefined)) {
                 // Filter down to the errors in the file
-                const fileErrors = diagnostics.filter(e => {
+                const fileErrors = diagnostics.filter((e): e is ts.DiagnosticWithLocation => {
                     const errFn = e.file;
                     return errFn && utils.removeTestPathPrefixes(errFn.fileName) === utils.removeTestPathPrefixes(inputFile.unitName);
                 });
diff --git a/src/harness/harnessLanguageService.ts b/src/harness/harnessLanguageService.ts
index 34d6f775a74b4..8c30f9411e671 100644
--- a/src/harness/harnessLanguageService.ts
+++ b/src/harness/harnessLanguageService.ts
@@ -398,13 +398,13 @@ namespace Harness.LanguageService {
         cleanupSemanticCache(): void {
             this.shim.cleanupSemanticCache();
         }
-        getSyntacticDiagnostics(fileName: string): ts.Diagnostic[] {
+        getSyntacticDiagnostics(fileName: string): ts.DiagnosticWithLocation[] {
             return unwrapJSONCallResult(this.shim.getSyntacticDiagnostics(fileName));
         }
-        getSemanticDiagnostics(fileName: string): ts.Diagnostic[] {
+        getSemanticDiagnostics(fileName: string): ts.DiagnosticWithLocation[] {
             return unwrapJSONCallResult(this.shim.getSemanticDiagnostics(fileName));
         }
-        getSuggestionDiagnostics(fileName: string): ts.Diagnostic[] {
+        getSuggestionDiagnostics(fileName: string): ts.DiagnosticWithLocation[] {
             return unwrapJSONCallResult(this.shim.getSuggestionDiagnostics(fileName));
         }
         getCompilerOptionsDiagnostics(): ts.Diagnostic[] {
diff --git a/src/harness/projectsRunner.ts b/src/harness/projectsRunner.ts
index 08e92a73be235..9ef536ad0c8be 100644
--- a/src/harness/projectsRunner.ts
+++ b/src/harness/projectsRunner.ts
@@ -154,7 +154,7 @@ namespace project {
                 const configParseResult = ts.parseJsonSourceFileConfigFileContent(result, configParseHost, ts.getDirectoryPath(configFileName), this.compilerOptions);
                 inputFiles = configParseResult.fileNames;
                 this.compilerOptions = configParseResult.options;
-                errors = result.parseDiagnostics.concat(configParseResult.errors);
+                errors = [...result.parseDiagnostics, ...configParseResult.errors];
             }
 
             const compilerHost = new ProjectCompilerHost(this.sys, this.compilerOptions, this.testCaseJustName, this.testCase, moduleKind);
diff --git a/src/harness/unittests/organizeImports.ts b/src/harness/unittests/organizeImports.ts
index 94f99856777e7..9dea2d0d51e85 100644
--- a/src/harness/unittests/organizeImports.ts
+++ b/src/harness/unittests/organizeImports.ts
@@ -506,7 +506,29 @@ D();
                 },
                 libFile);
 
-            testOrganizeImports("JsxFactoryUsed",
+            testOrganizeImports("JsxFactoryUsedJsx",
+                {
+                    path: "/test.jsx",
+                    content: `
+import { React, Other } from "react";
+
+<div/>;
+`,
+                },
+                reactLibFile);
+
+            testOrganizeImports("JsxFactoryUsedJs",
+                {
+                    path: "/test.js",
+                    content: `
+import { React, Other } from "react";
+
+<div/>;
+`,
+                },
+                reactLibFile);
+
+            testOrganizeImports("JsxFactoryUsedTsx",
                 {
                     path: "/test.tsx",
                     content: `
@@ -517,7 +539,39 @@ import { React, Other } from "react";
                 },
                 reactLibFile);
 
-            // This is descriptive, rather than normative
+            // TS files are not JSX contexts, so the parser does not treat
+            // `<div/>` as a JSX element.
+            testOrganizeImports("JsxFactoryUsedTs",
+                {
+                    path: "/test.ts",
+                    content: `
+import { React, Other } from "react";
+
+<div/>;
+`,
+                },
+                reactLibFile);
+
+            testOrganizeImports("JsxFactoryUnusedJsx",
+                {
+                    path: "/test.jsx",
+                    content: `
+import { React, Other } from "react";
+`,
+                },
+                reactLibFile);
+
+            // Note: Since the file extension does not end with "x", the jsx compiler option
+            // will not be enabled.  The import should be retained regardless.
+            testOrganizeImports("JsxFactoryUnusedJs",
+                {
+                    path: "/test.js",
+                    content: `
+import { React, Other } from "react";
+`,
+                },
+                reactLibFile);
+
             testOrganizeImports("JsxFactoryUnusedTsx",
                 {
                     path: "/test.tsx",
diff --git a/src/harness/unittests/tsserverProjectSystem.ts b/src/harness/unittests/tsserverProjectSystem.ts
index 7a5f97b06d5ec..1e75957feefea 100644
--- a/src/harness/unittests/tsserverProjectSystem.ts
+++ b/src/harness/unittests/tsserverProjectSystem.ts
@@ -407,6 +407,12 @@ namespace ts.projectSystem {
         checkArray("Open files", arrayFrom(projectService.openFiles.keys(), path => projectService.getScriptInfoForPath(path as Path).fileName), expectedFiles.map(file => file.path));
     }
 
+    function textSpanFromSubstring(str: string, substring: string): TextSpan {
+        const start = str.indexOf(substring);
+        Debug.assert(start !== -1);
+        return createTextSpan(start, substring.length);
+    }
+
     /**
      * Test server cancellation token used to mock host token cancellation requests.
      * The cancelAfterRequest constructor param specifies how many isCancellationRequested() calls
@@ -7445,10 +7451,17 @@ namespace ts.projectSystem {
         });
 
         describe("when event handler is not set but session is created with canUseEvents = true", () => {
-            verifyProjectsUpdatedInBackgroundEvent(createSessionThatUsesEvents);
+            describe("without noGetErrOnBackgroundUpdate, diagnostics for open files are queued", () => {
+                verifyProjectsUpdatedInBackgroundEvent(createSessionThatUsesEvents);
+            });
 
-            function createSessionThatUsesEvents(host: TestServerHost): ProjectsUpdatedInBackgroundEventVerifier {
-                const session = createSession(host, { canUseEvents: true });
+            describe("with noGetErrOnBackgroundUpdate, diagnostics for open file are not queued", () => {
+                verifyProjectsUpdatedInBackgroundEvent(host => createSessionThatUsesEvents(host, /*noGetErrOnBackgroundUpdate*/ true));
+            });
+
+
+            function createSessionThatUsesEvents(host: TestServerHost, noGetErrOnBackgroundUpdate?: boolean): ProjectsUpdatedInBackgroundEventVerifier {
+                const session = createSession(host, { canUseEvents: true, noGetErrOnBackgroundUpdate });
 
                 return {
                     session,
@@ -7480,6 +7493,10 @@ namespace ts.projectSystem {
 
                     // Verified the events, reset them
                     session.clearMessages();
+
+                    if (events.length) {
+                        host.checkTimeoutQueueLength(noGetErrOnBackgroundUpdate ? 0 : 1); // Error checking queued only if not noGetErrOnBackgroundUpdate
+                    }
                 }
             }
         });
@@ -8409,9 +8426,96 @@ new C();`
         });
     });
 
-    function textSpanFromSubstring(str: string, substring: string): TextSpan {
-        const start = str.indexOf(substring);
-        Debug.assert(start !== -1);
-        return createTextSpan(start, substring.length);
-    }
+    describe("document registry in project service", () => {
+        const projectRootPath = "/user/username/projects/project";
+        const importModuleContent = `import {a} from "./module1"`;
+        const file: File = {
+            path: `${projectRootPath}/index.ts`,
+            content: importModuleContent
+        };
+        const moduleFile: File = {
+            path: `${projectRootPath}/module1.d.ts`,
+            content: "export const a: number;"
+        };
+        const configFile: File = {
+            path: `${projectRootPath}/tsconfig.json`,
+            content: JSON.stringify({ files: ["index.ts"] })
+        };
+
+        function getProject(service: TestProjectService) {
+            return service.configuredProjects.get(configFile.path);
+        }
+
+        function checkProject(service: TestProjectService, moduleIsOrphan: boolean) {
+            // Update the project
+            const project = getProject(service);
+            project.getLanguageService();
+            checkProjectActualFiles(project, [file.path, libFile.path, configFile.path, ...(moduleIsOrphan ? [] : [moduleFile.path])]);
+            const moduleInfo = service.getScriptInfo(moduleFile.path);
+            assert.isDefined(moduleInfo);
+            assert.equal(moduleInfo.isOrphan(), moduleIsOrphan);
+            const key = service.documentRegistry.getKeyForCompilationSettings(project.getCompilationSettings());
+            assert.deepEqual(service.documentRegistry.getLanguageServiceRefCounts(moduleInfo.path), [[key, moduleIsOrphan ? undefined : 1]]);
+        }
+
+        function createServiceAndHost() {
+            const host = createServerHost([file, moduleFile, libFile, configFile]);
+            const service = createProjectService(host);
+            service.openClientFile(file.path);
+            checkProject(service, /*moduleIsOrphan*/ false);
+            return { host, service };
+        }
+
+        function changeFileToNotImportModule(service: TestProjectService) {
+            const info = service.getScriptInfo(file.path);
+            service.applyChangesToFile(info, [{ span: { start: 0, length: importModuleContent.length }, newText: "" }]);
+            checkProject(service, /*moduleIsOrphan*/ true);
+        }
+
+        function changeFileToImportModule(service: TestProjectService) {
+            const info = service.getScriptInfo(file.path);
+            service.applyChangesToFile(info, [{ span: { start: 0, length: 0 }, newText: importModuleContent }]);
+            checkProject(service, /*moduleIsOrphan*/ false);
+        }
+
+        it("Caches the source file if script info is orphan", () => {
+            const { service } = createServiceAndHost();
+            const project = getProject(service);
+
+            const moduleInfo = service.getScriptInfo(moduleFile.path);
+            const sourceFile = moduleInfo.cacheSourceFile.sourceFile;
+            assert.equal(project.getSourceFile(moduleInfo.path), sourceFile);
+
+            // edit file
+            changeFileToNotImportModule(service);
+            assert.equal(moduleInfo.cacheSourceFile.sourceFile, sourceFile);
+
+            // write content back
+            changeFileToImportModule(service);
+            assert.equal(moduleInfo.cacheSourceFile.sourceFile, sourceFile);
+            assert.equal(project.getSourceFile(moduleInfo.path), sourceFile);
+        });
+
+        it("Caches the source file if script info is orphan, and orphan script info changes", () => {
+            const { host, service } = createServiceAndHost();
+            const project = getProject(service);
+
+            const moduleInfo = service.getScriptInfo(moduleFile.path);
+            const sourceFile = moduleInfo.cacheSourceFile.sourceFile;
+            assert.equal(project.getSourceFile(moduleInfo.path), sourceFile);
+
+            // edit file
+            changeFileToNotImportModule(service);
+            assert.equal(moduleInfo.cacheSourceFile.sourceFile, sourceFile);
+
+            const updatedModuleContent = moduleFile.content + "\nexport const b: number;";
+            host.writeFile(moduleFile.path, updatedModuleContent);
+
+            // write content back
+            changeFileToImportModule(service);
+            assert.notEqual(moduleInfo.cacheSourceFile.sourceFile, sourceFile);
+            assert.equal(project.getSourceFile(moduleInfo.path), moduleInfo.cacheSourceFile.sourceFile);
+            assert.equal(moduleInfo.cacheSourceFile.sourceFile.text, updatedModuleContent);
+        });
+    });
 }
diff --git a/src/server/client.ts b/src/server/client.ts
index a07e793dcba55..2a97a54a18dcc 100644
--- a/src/server/client.ts
+++ b/src/server/client.ts
@@ -346,21 +346,21 @@ namespace ts.server {
             return notImplemented();
         }
 
-        getSyntacticDiagnostics(file: string): Diagnostic[] {
+        getSyntacticDiagnostics(file: string): DiagnosticWithLocation[] {
             return this.getDiagnostics(file, CommandNames.SyntacticDiagnosticsSync);
         }
-        getSemanticDiagnostics(file: string): Diagnostic[] {
+        getSemanticDiagnostics(file: string): DiagnosticWithLocation[] {
             return this.getDiagnostics(file, CommandNames.SemanticDiagnosticsSync);
         }
-        getSuggestionDiagnostics(file: string): Diagnostic[] {
+        getSuggestionDiagnostics(file: string): DiagnosticWithLocation[] {
             return this.getDiagnostics(file, CommandNames.SuggestionDiagnosticsSync);
         }
 
-        private getDiagnostics(file: string, command: CommandNames): Diagnostic[] {
+        private getDiagnostics(file: string, command: CommandNames): DiagnosticWithLocation[] {
             const request = this.processRequest<protocol.SyntacticDiagnosticsSyncRequest | protocol.SemanticDiagnosticsSyncRequest | protocol.SuggestionDiagnosticsSyncRequest>(command, { file, includeLinePosition: true });
             const response = this.processResponse<protocol.SyntacticDiagnosticsSyncResponse | protocol.SemanticDiagnosticsSyncResponse | protocol.SuggestionDiagnosticsSyncResponse>(request);
 
-            return (<protocol.DiagnosticWithLinePosition[]>response.body).map((entry): Diagnostic => {
+            return (<protocol.DiagnosticWithLinePosition[]>response.body).map((entry): DiagnosticWithLocation => {
                 const category = firstDefined(Object.keys(DiagnosticCategory), id =>
                     isString(id) && entry.category === id.toLowerCase() ? (<any>DiagnosticCategory)[id] : undefined);
                 return {
diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index bb3560cbde521..71c5791187721 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -339,7 +339,8 @@ namespace ts.server {
         /*@internal*/
         readonly typingsCache: TypingsCache;
 
-        private readonly documentRegistry: DocumentRegistry;
+        /*@internal*/
+        readonly documentRegistry: DocumentRegistry;
 
         /**
          * Container of all known scripts
@@ -403,7 +404,7 @@ namespace ts.server {
         /* @internal */
         pendingEnsureProjectForOpenFiles: boolean;
 
-        readonly currentDirectory: string;
+        readonly currentDirectory: NormalizedPath;
         readonly toCanonicalFileName: (f: string) => string;
 
         public readonly host: ServerHost;
@@ -450,7 +451,7 @@ namespace ts.server {
             if (this.host.realpath) {
                 this.realpathToScriptInfos = createMultiMap();
             }
-            this.currentDirectory = this.host.getCurrentDirectory();
+            this.currentDirectory = toNormalizedPath(this.host.getCurrentDirectory());
             this.toCanonicalFileName = createGetCanonicalFileName(this.host.useCaseSensitiveFileNames);
             this.globalCacheLocationDirectoryPath = this.typingsInstaller.globalTypingsCacheLocation &&
                 ensureTrailingDirectorySeparator(this.toPath(this.typingsInstaller.globalTypingsCacheLocation));
@@ -474,7 +475,7 @@ namespace ts.server {
                 extraFileExtensions: []
             };
 
-            this.documentRegistry = createDocumentRegistry(this.host.useCaseSensitiveFileNames, this.currentDirectory);
+            this.documentRegistry = createDocumentRegistryInternal(this.host.useCaseSensitiveFileNames, this.currentDirectory, this);
             const watchLogLevel = this.logger.hasLevel(LogLevel.verbose) ? WatchLogLevel.Verbose :
                 this.logger.loggingEnabled() ? WatchLogLevel.TriggerOnly : WatchLogLevel.None;
             const log: (s: string) => void = watchLogLevel !== WatchLogLevel.None ? (s => this.logger.info(s)) : noop;
@@ -495,6 +496,19 @@ namespace ts.server {
             return getNormalizedAbsolutePath(fileName, this.host.getCurrentDirectory());
         }
 
+        /*@internal*/
+        setDocument(key: DocumentRegistryBucketKey, path: Path, sourceFile: SourceFile) {
+            const info = this.getScriptInfoForPath(path);
+            Debug.assert(!!info);
+            info.cacheSourceFile = { key, sourceFile };
+        }
+
+        /*@internal*/
+        getDocument(key: DocumentRegistryBucketKey, path: Path) {
+            const info = this.getScriptInfoForPath(path);
+            return info && info.cacheSourceFile && info.cacheSourceFile.key === key && info.cacheSourceFile.sourceFile;
+        }
+
         /* @internal */
         ensureInferredProjectsUpToDate_TestOnly() {
             this.ensureProjectStructuresUptoDate();
@@ -1329,7 +1343,7 @@ namespace ts.server {
             if (!result.endOfFileToken) {
                 result.endOfFileToken = <EndOfFileToken>{ kind: SyntaxKind.EndOfFileToken };
             }
-            const errors = result.parseDiagnostics;
+            const errors = result.parseDiagnostics as Diagnostic[];
             const parsedCommandLine = parseJsonSourceFileConfigFileContent(
                 result,
                 cachedDirectoryStructureHost,
diff --git a/src/server/scriptInfo.ts b/src/server/scriptInfo.ts
index efae3a5faa68d..c47f3daecb9a5 100644
--- a/src/server/scriptInfo.ts
+++ b/src/server/scriptInfo.ts
@@ -202,6 +202,12 @@ namespace ts.server {
         return fileName[0] === "^" || getBaseFileName(fileName)[0] === "^";
     }
 
+    /*@internal*/
+    export interface DocumentRegistrySourceFileCache {
+        key: DocumentRegistryBucketKey;
+        sourceFile: SourceFile;
+    }
+
     export class ScriptInfo {
         /**
          * All projects that include this file
@@ -221,6 +227,9 @@ namespace ts.server {
         /** Set to real path if path is different from info.path */
         private realpath: Path | undefined;
 
+        /*@internal*/
+        cacheSourceFile: DocumentRegistrySourceFileCache;
+
         constructor(
             private readonly host: ServerHost,
             readonly fileName: NormalizedPath,
diff --git a/src/server/server.ts b/src/server/server.ts
index 6eff32563497a..706a47a0aa5c5 100644
--- a/src/server/server.ts
+++ b/src/server/server.ts
@@ -505,6 +505,7 @@ namespace ts.server {
                 canUseEvents: true,
                 suppressDiagnosticEvents,
                 syntaxOnly,
+                noGetErrOnBackgroundUpdate,
                 globalPlugins,
                 pluginProbeLocations,
                 allowLocalPluginLoads,
@@ -939,6 +940,7 @@ namespace ts.server {
     const suppressDiagnosticEvents = hasArgument("--suppressDiagnosticEvents");
     const syntaxOnly = hasArgument("--syntaxOnly");
     const telemetryEnabled = hasArgument(Arguments.EnableTelemetry);
+    const noGetErrOnBackgroundUpdate = hasArgument("--noGetErrOnBackgroundUpdate");
 
     logger.info(`Starting TS Server`);
     logger.info(`Version: ${version}`);
diff --git a/src/server/session.ts b/src/server/session.ts
index 40f26785113cf..ccedad18aac89 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -295,6 +295,7 @@ namespace ts.server {
         suppressDiagnosticEvents?: boolean;
         syntaxOnly?: boolean;
         throttleWaitMilliseconds?: number;
+        noGetErrOnBackgroundUpdate?: boolean;
 
         globalPlugins?: ReadonlyArray<string>;
         pluginProbeLocations?: ReadonlyArray<string>;
@@ -319,6 +320,7 @@ namespace ts.server {
         protected canUseEvents: boolean;
         private suppressDiagnosticEvents?: boolean;
         private eventHandler: ProjectServiceEventHandler;
+        private readonly noGetErrOnBackgroundUpdate?: boolean;
 
         constructor(opts: SessionOptions) {
             this.host = opts.host;
@@ -329,6 +331,7 @@ namespace ts.server {
             this.logger = opts.logger;
             this.canUseEvents = opts.canUseEvents;
             this.suppressDiagnosticEvents = opts.suppressDiagnosticEvents;
+            this.noGetErrOnBackgroundUpdate = opts.noGetErrOnBackgroundUpdate;
 
             const { throttleWaitMilliseconds } = opts;
 
@@ -404,7 +407,7 @@ namespace ts.server {
         private projectsUpdatedInBackgroundEvent(openFiles: string[]): void {
             this.projectService.logger.info(`got projects updated in background, updating diagnostics for ${openFiles}`);
             if (openFiles.length) {
-                if (!this.suppressDiagnosticEvents) {
+                if (!this.suppressDiagnosticEvents && !this.noGetErrOnBackgroundUpdate) {
                     const checkList = this.createCheckList(openFiles);
 
                     // For now only queue error checking for open files. We can change this to include non open files as well
diff --git a/src/services/codeFixProvider.ts b/src/services/codeFixProvider.ts
index 39f760ba04cf1..31b766d3bf5a3 100644
--- a/src/services/codeFixProvider.ts
+++ b/src/services/codeFixProvider.ts
@@ -79,17 +79,17 @@ namespace ts {
             return { fileName, textChanges };
         }
 
-        export function codeFixAll(context: CodeFixAllContext, errorCodes: number[], use: (changes: textChanges.ChangeTracker, error: Diagnostic, commands: Push<CodeActionCommand>) => void): CombinedCodeActions {
+        export function codeFixAll(context: CodeFixAllContext, errorCodes: number[], use: (changes: textChanges.ChangeTracker, error: DiagnosticWithLocation, commands: Push<CodeActionCommand>) => void): CombinedCodeActions {
             const commands: CodeActionCommand[] = [];
             const changes = textChanges.ChangeTracker.with(context, t =>
                 eachDiagnostic(context, errorCodes, diag => use(t, diag, commands)));
             return createCombinedCodeActions(changes, commands.length === 0 ? undefined : commands);
         }
 
-        function eachDiagnostic({ program, sourceFile }: CodeFixAllContext, errorCodes: number[], cb: (diag: Diagnostic) => void): void {
+        function eachDiagnostic({ program, sourceFile }: CodeFixAllContext, errorCodes: number[], cb: (diag: DiagnosticWithLocation) => void): void {
             for (const diag of program.getSemanticDiagnostics(sourceFile).concat(computeSuggestionDiagnostics(sourceFile, program))) {
                 if (contains(errorCodes, diag.code)) {
-                    cb(diag);
+                    cb(diag as DiagnosticWithLocation);
                 }
             }
         }
diff --git a/src/services/codefixes/addMissingInvocationForDecorator.ts b/src/services/codefixes/addMissingInvocationForDecorator.ts
index ead64f9a2ca9e..02b97eec37ebf 100644
--- a/src/services/codefixes/addMissingInvocationForDecorator.ts
+++ b/src/services/codefixes/addMissingInvocationForDecorator.ts
@@ -9,7 +9,7 @@ namespace ts.codefix {
             return [createCodeFixAction(fixId, changes, Diagnostics.Call_decorator_expression, fixId, Diagnostics.Add_to_all_uncalled_decorators)];
         },
         fixIds: [fixId],
-        getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => makeChange(changes, diag.file!, diag.start!)),
+        getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => makeChange(changes, diag.file, diag.start)),
     });
 
     function makeChange(changeTracker: textChanges.ChangeTracker, sourceFile: SourceFile, pos: number) {
diff --git a/src/services/codefixes/annotateWithTypeFromJSDoc.ts b/src/services/codefixes/annotateWithTypeFromJSDoc.ts
index 7b66467843650..b3fc09b7bc4b2 100644
--- a/src/services/codefixes/annotateWithTypeFromJSDoc.ts
+++ b/src/services/codefixes/annotateWithTypeFromJSDoc.ts
@@ -12,8 +12,8 @@ namespace ts.codefix {
         },
         fixIds: [fixId],
         getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => {
-            const decl = getDeclaration(diag.file!, diag.start!);
-            if (decl) doChange(changes, diag.file!, decl);
+            const decl = getDeclaration(diag.file, diag.start);
+            if (decl) doChange(changes, diag.file, decl);
         }),
     });
 
diff --git a/src/services/codefixes/disableJsDiagnostics.ts b/src/services/codefixes/disableJsDiagnostics.ts
index b5d3059dd42cb..c81446152dd05 100644
--- a/src/services/codefixes/disableJsDiagnostics.ts
+++ b/src/services/codefixes/disableJsDiagnostics.ts
@@ -38,8 +38,8 @@ namespace ts.codefix {
         getAllCodeActions: context => {
             const seenLines = createMap<true>();
             return codeFixAll(context, errorCodes, (changes, diag) => {
-                if (textChanges.isValidLocationToAddComment(diag.file!, diag.start!)) {
-                    makeChange(changes, diag.file!, diag.start!, seenLines);
+                if (textChanges.isValidLocationToAddComment(diag.file, diag.start)) {
+                    makeChange(changes, diag.file, diag.start, seenLines);
                 }
             });
         },
diff --git a/src/services/codefixes/fixAddMissingMember.ts b/src/services/codefixes/fixAddMissingMember.ts
index e53ce41ad8a75..c2a8316db379a 100644
--- a/src/services/codefixes/fixAddMissingMember.ts
+++ b/src/services/codefixes/fixAddMissingMember.ts
@@ -23,7 +23,7 @@ namespace ts.codefix {
             const seenNames = createMap<true>();
             return codeFixAll(context, errorCodes, (changes, diag) => {
                 const { program, preferences } = context;
-                const info = getInfo(diag.file!, diag.start!, program.getTypeChecker());
+                const info = getInfo(diag.file, diag.start, program.getTypeChecker());
                 if (!info) return;
                 const { classDeclaration, classDeclarationSourceFile, inJs, makeStatic, token, call } = info;
                 if (!addToSeen(seenNames, token.text)) {
diff --git a/src/services/codefixes/fixClassDoesntImplementInheritedAbstractMember.ts b/src/services/codefixes/fixClassDoesntImplementInheritedAbstractMember.ts
index a931f849cb235..d59df7a02b302 100644
--- a/src/services/codefixes/fixClassDoesntImplementInheritedAbstractMember.ts
+++ b/src/services/codefixes/fixClassDoesntImplementInheritedAbstractMember.ts
@@ -17,7 +17,7 @@ namespace ts.codefix {
         getAllCodeActions: context => {
             const seenClassDeclarations = createMap<true>();
             return codeFixAll(context, errorCodes, (changes, diag) => {
-                const classDeclaration = getClass(diag.file!, diag.start!);
+                const classDeclaration = getClass(diag.file, diag.start);
                 if (addToSeen(seenClassDeclarations, getNodeId(classDeclaration))) {
                     addMissingMembers(classDeclaration, context.sourceFile, context.program.getTypeChecker(), changes, context.preferences);
                 }
diff --git a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
index 4e0b5745149b4..0da45c46873dd 100644
--- a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
+++ b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
@@ -18,10 +18,10 @@ namespace ts.codefix {
         getAllCodeActions(context) {
             const seenClassDeclarations = createMap<true>();
             return codeFixAll(context, errorCodes, (changes, diag) => {
-                const classDeclaration = getClass(diag.file!, diag.start!);
+                const classDeclaration = getClass(diag.file, diag.start);
                 if (addToSeen(seenClassDeclarations, getNodeId(classDeclaration))) {
                     for (const implementedTypeNode of getClassImplementsHeritageClauseElements(classDeclaration)) {
-                        addMissingDeclarations(context.program.getTypeChecker(), implementedTypeNode, diag.file!, classDeclaration, changes, context.preferences);
+                        addMissingDeclarations(context.program.getTypeChecker(), implementedTypeNode, diag.file, classDeclaration, changes, context.preferences);
                     }
                 }
             });
diff --git a/src/services/codefixes/fixClassSuperMustPrecedeThisAccess.ts b/src/services/codefixes/fixClassSuperMustPrecedeThisAccess.ts
index af38b8e9025fd..2f7daf93dc735 100644
--- a/src/services/codefixes/fixClassSuperMustPrecedeThisAccess.ts
+++ b/src/services/codefixes/fixClassSuperMustPrecedeThisAccess.ts
@@ -17,7 +17,7 @@ namespace ts.codefix {
             const { sourceFile } = context;
             const seenClasses = createMap<true>(); // Ensure we only do this once per class.
             return codeFixAll(context, errorCodes, (changes, diag) => {
-                const nodes = getNodes(diag.file!, diag.start!);
+                const nodes = getNodes(diag.file, diag.start);
                 if (!nodes) return;
                 const { constructor, superCall } = nodes;
                 if (addToSeen(seenClasses, getNodeId(constructor.parent))) {
diff --git a/src/services/codefixes/fixConstructorForDerivedNeedSuperCall.ts b/src/services/codefixes/fixConstructorForDerivedNeedSuperCall.ts
index 2aed263ee833f..605bb660f0623 100644
--- a/src/services/codefixes/fixConstructorForDerivedNeedSuperCall.ts
+++ b/src/services/codefixes/fixConstructorForDerivedNeedSuperCall.ts
@@ -12,7 +12,7 @@ namespace ts.codefix {
         },
         fixIds: [fixId],
         getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) =>
-            doChange(changes, context.sourceFile, getNode(diag.file, diag.start!))),
+            doChange(changes, context.sourceFile, getNode(diag.file, diag.start))),
     });
 
     function getNode(sourceFile: SourceFile, pos: number): ConstructorDeclaration {
diff --git a/src/services/codefixes/fixExtendsInterfaceBecomesImplements.ts b/src/services/codefixes/fixExtendsInterfaceBecomesImplements.ts
index c3f406b847509..4320513fb617c 100644
--- a/src/services/codefixes/fixExtendsInterfaceBecomesImplements.ts
+++ b/src/services/codefixes/fixExtendsInterfaceBecomesImplements.ts
@@ -14,7 +14,7 @@ namespace ts.codefix {
         },
         fixIds: [fixId],
         getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => {
-            const nodes = getNodes(diag.file, diag.start!);
+            const nodes = getNodes(diag.file, diag.start);
             if (nodes) doChanges(changes, diag.file, nodes.extendsToken, nodes.heritageClauses);
         }),
     });
diff --git a/src/services/codefixes/fixForgottenThisPropertyAccess.ts b/src/services/codefixes/fixForgottenThisPropertyAccess.ts
index 31c6128d003f4..ce066277a27e2 100644
--- a/src/services/codefixes/fixForgottenThisPropertyAccess.ts
+++ b/src/services/codefixes/fixForgottenThisPropertyAccess.ts
@@ -19,7 +19,7 @@ namespace ts.codefix {
         },
         fixIds: [fixId],
         getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => {
-            doChange(changes, context.sourceFile, getInfo(diag.file, diag.start!, diag.code));
+            doChange(changes, context.sourceFile, getInfo(diag.file, diag.start, diag.code));
         }),
     });
 
diff --git a/src/services/codefixes/fixSpelling.ts b/src/services/codefixes/fixSpelling.ts
index 252b08b356af1..dbb23c3ac09dd 100644
--- a/src/services/codefixes/fixSpelling.ts
+++ b/src/services/codefixes/fixSpelling.ts
@@ -19,7 +19,7 @@ namespace ts.codefix {
         },
         fixIds: [fixId],
         getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => {
-            const info = getInfo(diag.file!, diag.start!, context);
+            const info = getInfo(diag.file, diag.start, context);
             const { target } = context.host.getCompilationSettings();
             if (info) doChange(changes, context.sourceFile, info.node, info.suggestion, target);
         }),
diff --git a/src/services/codefixes/fixUnusedIdentifier.ts b/src/services/codefixes/fixUnusedIdentifier.ts
index 148b42b1c7e61..6ba592ca2b8b5 100644
--- a/src/services/codefixes/fixUnusedIdentifier.ts
+++ b/src/services/codefixes/fixUnusedIdentifier.ts
@@ -53,7 +53,7 @@ namespace ts.codefix {
             return codeFixAll(context, errorCodes, (changes, diag) => {
                 const { sourceFile } = context;
                 const startToken = getTokenAtPosition(sourceFile, diag.start, /*includeJsDocComment*/ false);
-                const token = findPrecedingToken(textSpanEnd(diag), diag.file!);
+                const token = findPrecedingToken(textSpanEnd(diag), diag.file);
                 switch (context.fixId) {
                     case fixIdPrefix:
                         if (isIdentifier(token) && canPrefix(token)) {
@@ -62,7 +62,7 @@ namespace ts.codefix {
                         break;
                     case fixIdDelete:
                         // Ignore if this range was already deleted.
-                        if (deleted.some(d => rangeContainsPosition(d, diag.start!))) break;
+                        if (deleted.some(d => rangeContainsPosition(d, diag.start))) break;
 
                         const importDecl = tryGetFullImport(startToken);
                         if (importDecl) {
diff --git a/src/services/codefixes/useDefaultImport.ts b/src/services/codefixes/useDefaultImport.ts
index 99fc145b5630a..3fe451c41fb2a 100644
--- a/src/services/codefixes/useDefaultImport.ts
+++ b/src/services/codefixes/useDefaultImport.ts
@@ -13,8 +13,8 @@ namespace ts.codefix {
         },
         fixIds: [fixId],
         getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => {
-            const info = getInfo(diag.file!, diag.start!);
-            if (info) doChange(changes, diag.file!, info);
+            const info = getInfo(diag.file, diag.start);
+            if (info) doChange(changes, diag.file, info);
         }),
     });
 
diff --git a/src/services/documentRegistry.ts b/src/services/documentRegistry.ts
index d464f7a408acc..05f6548c62b73 100644
--- a/src/services/documentRegistry.ts
+++ b/src/services/documentRegistry.ts
@@ -87,9 +87,18 @@ namespace ts {
 
         releaseDocumentWithKey(path: Path, key: DocumentRegistryBucketKey): void;
 
+        /*@internal*/
+        getLanguageServiceRefCounts(path: Path): [string, number | undefined][];
+
         reportStats(): string;
     }
 
+    /*@internal*/
+    export interface ExternalDocumentCache {
+        setDocument(key: DocumentRegistryBucketKey, path: Path, sourceFile: SourceFile): void;
+        getDocument(key: DocumentRegistryBucketKey, path: Path): SourceFile | undefined;
+    }
+
     export type DocumentRegistryBucketKey = string & { __bucketKey: any };
 
     interface DocumentRegistryEntry {
@@ -99,10 +108,14 @@ namespace ts {
         // language services are referencing the file, then the file can be removed from the
         // registry.
         languageServiceRefCount: number;
-        owners: string[];
     }
 
-    export function createDocumentRegistry(useCaseSensitiveFileNames?: boolean, currentDirectory = ""): DocumentRegistry {
+    export function createDocumentRegistry(useCaseSensitiveFileNames?: boolean, currentDirectory?: string): DocumentRegistry {
+        return createDocumentRegistryInternal(useCaseSensitiveFileNames, currentDirectory);
+    }
+
+    /*@internal*/
+    export function createDocumentRegistryInternal(useCaseSensitiveFileNames?: boolean, currentDirectory = "", externalCache?: ExternalDocumentCache): DocumentRegistry {
         // Maps from compiler setting target (ES3, ES5, etc.) to all the cached documents we have
         // for those settings.
         const buckets = createMap<Map<DocumentRegistryEntry>>();
@@ -123,12 +136,11 @@ namespace ts {
         function reportStats() {
             const bucketInfoArray = arrayFrom(buckets.keys()).filter(name => name && name.charAt(0) === "_").map(name => {
                 const entries = buckets.get(name);
-                const sourceFiles: { name: string; refCount: number; references: string[]; }[] = [];
+                const sourceFiles: { name: string; refCount: number; }[] = [];
                 entries.forEach((entry, name) => {
                     sourceFiles.push({
                         name,
-                        refCount: entry.languageServiceRefCount,
-                        references: entry.owners.slice(0)
+                        refCount: entry.languageServiceRefCount
                     });
                 });
                 sourceFiles.sort((x, y) => y.refCount - x.refCount);
@@ -173,14 +185,27 @@ namespace ts {
             const bucket = getBucketForCompilationSettings(key, /*createIfMissing*/ true);
             let entry = bucket.get(path);
             const scriptTarget = scriptKind === ScriptKind.JSON ? ScriptTarget.JSON : compilationSettings.target;
+            if (!entry && externalCache) {
+                const sourceFile = externalCache.getDocument(key, path);
+                if (sourceFile) {
+                    Debug.assert(acquiring);
+                    entry = {
+                        sourceFile,
+                        languageServiceRefCount: 0
+                    };
+                    bucket.set(path, entry);
+                }
+            }
+
             if (!entry) {
                 // Have never seen this file with these settings.  Create a new source file for it.
                 const sourceFile = createLanguageServiceSourceFile(fileName, scriptSnapshot, scriptTarget, version, /*setNodeParents*/ false, scriptKind);
-
+                if (externalCache) {
+                    externalCache.setDocument(key, path, sourceFile);
+                }
                 entry = {
                     sourceFile,
                     languageServiceRefCount: 1,
-                    owners: []
                 };
                 bucket.set(path, entry);
             }
@@ -191,6 +216,9 @@ namespace ts {
                 if (entry.sourceFile.version !== version) {
                     entry.sourceFile = updateLanguageServiceSourceFile(entry.sourceFile, scriptSnapshot, version,
                         scriptSnapshot.getChangeRange(entry.sourceFile.scriptSnapshot));
+                    if (externalCache) {
+                        externalCache.setDocument(key, path, entry.sourceFile);
+                    }
                 }
 
                 // If we're acquiring, then this is the first time this LS is asking for this document.
@@ -202,6 +230,7 @@ namespace ts {
                     entry.languageServiceRefCount++;
                 }
             }
+            Debug.assert(entry.languageServiceRefCount !== 0);
 
             return entry.sourceFile;
         }
@@ -225,6 +254,13 @@ namespace ts {
             }
         }
 
+        function getLanguageServiceRefCounts(path: Path) {
+            return arrayFrom(buckets.entries(), ([key, bucket]): [string, number | undefined] => {
+                const entry = bucket.get(path);
+                return [key, entry && entry.languageServiceRefCount];
+            });
+        }
+
         return {
             acquireDocument,
             acquireDocumentWithKey,
@@ -232,6 +268,7 @@ namespace ts {
             updateDocumentWithKey,
             releaseDocument,
             releaseDocumentWithKey,
+            getLanguageServiceRefCounts,
             reportStats,
             getKeyForCompilationSettings
         };
diff --git a/src/services/formatting/formatting.ts b/src/services/formatting/formatting.ts
index 494a811c238de..b0273cc18e7a4 100644
--- a/src/services/formatting/formatting.ts
+++ b/src/services/formatting/formatting.ts
@@ -228,7 +228,7 @@ namespace ts.formatting {
      * This function will return a predicate that for a given text range will tell
      * if there are any parse errors that overlap with the range.
      */
-    function prepareRangeContainsErrorFunction(errors: Diagnostic[], originalRange: TextRange): (r: TextRange) => boolean {
+    function prepareRangeContainsErrorFunction(errors: ReadonlyArray<Diagnostic>, originalRange: TextRange): (r: TextRange) => boolean {
         if (!errors.length) {
             return rangeHasNoErrors;
         }
diff --git a/src/services/formatting/smartIndenter.ts b/src/services/formatting/smartIndenter.ts
index a75781b8da0e4..4c93d7816e75d 100644
--- a/src/services/formatting/smartIndenter.ts
+++ b/src/services/formatting/smartIndenter.ts
@@ -569,6 +569,12 @@ namespace ts.formatting {
                     return childKind !== SyntaxKind.JsxClosingElement;
                 case SyntaxKind.JsxFragment:
                     return childKind !== SyntaxKind.JsxClosingFragment;
+                case SyntaxKind.IntersectionType:
+                case SyntaxKind.UnionType:
+                    if (childKind === SyntaxKind.TypeLiteral) {
+                        return false;
+                    }
+                    // falls through
             }
             // No explicit rule for given nodes so the result will follow the default value argument
             return indentByDefault;
diff --git a/src/services/organizeImports.ts b/src/services/organizeImports.ts
index 99bac64973f80..225e9fae57d76 100644
--- a/src/services/organizeImports.ts
+++ b/src/services/organizeImports.ts
@@ -92,7 +92,7 @@ namespace ts.OrganizeImports {
     function removeUnusedImports(oldImports: ReadonlyArray<ImportDeclaration>, sourceFile: SourceFile, program: Program) {
         const typeChecker = program.getTypeChecker();
         const jsxNamespace = typeChecker.getJsxNamespace();
-        const jsxContext = sourceFile.languageVariant === LanguageVariant.JSX && program.getCompilerOptions().jsx;
+        const jsxElementsPresent = !!(sourceFile.transformFlags & TransformFlags.ContainsJsx);
 
         const usedImports: ImportDeclaration[] = [];
 
@@ -138,8 +138,8 @@ namespace ts.OrganizeImports {
         return usedImports;
 
         function isDeclarationUsed(identifier: Identifier) {
-            // The JSX factory symbol is always used.
-            return jsxContext && (identifier.text === jsxNamespace) || FindAllReferences.Core.isSymbolReferencedInFile(identifier, typeChecker, sourceFile);
+            // The JSX factory symbol is always used if JSX elements are present - even if they are not allowed.
+            return jsxElementsPresent && (identifier.text === jsxNamespace) || FindAllReferences.Core.isSymbolReferencedInFile(identifier, typeChecker, sourceFile);
         }
     }
 
diff --git a/src/services/services.ts b/src/services/services.ts
index 3fcd4e8e151f8..0375f6fcf38f7 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -545,9 +545,10 @@ namespace ts {
         public referencedFiles: FileReference[];
         public typeReferenceDirectives: FileReference[];
 
-        public syntacticDiagnostics: Diagnostic[];
-        public parseDiagnostics: Diagnostic[];
-        public bindDiagnostics: Diagnostic[];
+        public syntacticDiagnostics: DiagnosticWithLocation[];
+        public parseDiagnostics: DiagnosticWithLocation[];
+        public bindDiagnostics: DiagnosticWithLocation[];
+        public bindSuggestionDiagnostics?: DiagnosticWithLocation[];
 
         public isDeclarationFile: boolean;
         public isDefaultLib: boolean;
@@ -1376,7 +1377,7 @@ namespace ts {
         }
 
         /// Diagnostics
-        function getSyntacticDiagnostics(fileName: string): Diagnostic[] {
+        function getSyntacticDiagnostics(fileName: string): DiagnosticWithLocation[] {
             synchronizeHostData();
 
             return program.getSyntacticDiagnostics(getValidSourceFile(fileName), cancellationToken).slice();
@@ -1404,7 +1405,7 @@ namespace ts {
             return [...semanticDiagnostics, ...declarationDiagnostics];
         }
 
-        function getSuggestionDiagnostics(fileName: string): Diagnostic[] {
+        function getSuggestionDiagnostics(fileName: string): DiagnosticWithLocation[] {
             synchronizeHostData();
             return computeSuggestionDiagnostics(getValidSourceFile(fileName), program);
         }
diff --git a/src/services/shims.ts b/src/services/shims.ts
index d0735cc171766..808da2eb1ec9c 100644
--- a/src/services/shims.ts
+++ b/src/services/shims.ts
@@ -586,7 +586,7 @@ namespace ts {
         length: number;
         category: string;
         code: number;
-        unused?: {};
+        reportsUnnecessary?: {};
     }
     export function realizeDiagnostics(diagnostics: ReadonlyArray<Diagnostic>, newLine: string): RealizedDiagnostic[] {
         return diagnostics.map(d => realizeDiagnostic(d, newLine));
@@ -598,7 +598,8 @@ namespace ts {
             start: diagnostic.start,
             length: diagnostic.length,
             category: diagnosticCategoryName(diagnostic),
-            code: diagnostic.code
+            code: diagnostic.code,
+            reportsUnnecessary: diagnostic.reportsUnnecessary,
         };
     }
 
@@ -1146,7 +1147,7 @@ namespace ts {
                         typeAcquisition: configFile.typeAcquisition,
                         files: configFile.fileNames,
                         raw: configFile.raw,
-                        errors: realizeDiagnostics(result.parseDiagnostics.concat(configFile.errors), "\r\n")
+                        errors: realizeDiagnostics([...result.parseDiagnostics, ...configFile.errors], "\r\n")
                     };
                 });
         }
diff --git a/src/services/suggestionDiagnostics.ts b/src/services/suggestionDiagnostics.ts
index 3135fdc368bbc..c59c267d16448 100644
--- a/src/services/suggestionDiagnostics.ts
+++ b/src/services/suggestionDiagnostics.ts
@@ -1,9 +1,9 @@
 /* @internal */
 namespace ts {
-    export function computeSuggestionDiagnostics(sourceFile: SourceFile, program: Program): Diagnostic[] {
+    export function computeSuggestionDiagnostics(sourceFile: SourceFile, program: Program): DiagnosticWithLocation[] {
         program.getSemanticDiagnostics(sourceFile);
         const checker = program.getDiagnosticsProducingTypeChecker();
-        const diags: Diagnostic[] = [];
+        const diags: DiagnosticWithLocation[] = [];
 
         if (sourceFile.commonJsModuleIndicator &&
             (programContainsEs6Modules(program) || compilerOptionsIndicateEs6Modules(program.getCompilerOptions())) &&
@@ -60,6 +60,7 @@ namespace ts {
             }
         }
 
+        addRange(diags, sourceFile.bindSuggestionDiagnostics);
         return diags.concat(checker.getSuggestionDiagnostics(sourceFile)).sort((d1, d2) => d1.start - d2.start);
     }
 
diff --git a/src/services/transform.ts b/src/services/transform.ts
index 200fb9aacb249..b6b2a35708104 100644
--- a/src/services/transform.ts
+++ b/src/services/transform.ts
@@ -6,7 +6,7 @@ namespace ts {
      * @param compilerOptions Optional compiler options.
      */
     export function transform<T extends Node>(source: T | T[], transformers: TransformerFactory<T>[], compilerOptions?: CompilerOptions) {
-        const diagnostics: Diagnostic[] = [];
+        const diagnostics: DiagnosticWithLocation[] = [];
         compilerOptions = fixupCompilerOptions(compilerOptions, diagnostics);
         const nodes = isArray(source) ? source : [source];
         const result = transformNodes(/*resolver*/ undefined, /*emitHost*/ undefined, compilerOptions, nodes, transformers, /*allowDtsFiles*/ true);
diff --git a/src/services/types.ts b/src/services/types.ts
index b8e2c488b17cb..b1b0ccd6de885 100644
--- a/src/services/types.ts
+++ b/src/services/types.ts
@@ -249,9 +249,10 @@ namespace ts {
     export interface LanguageService {
         cleanupSemanticCache(): void;
 
-        getSyntacticDiagnostics(fileName: string): Diagnostic[];
+        getSyntacticDiagnostics(fileName: string): DiagnosticWithLocation[];
+        /** The first time this is called, it will return global diagnostics (no location). */
         getSemanticDiagnostics(fileName: string): Diagnostic[];
-        getSuggestionDiagnostics(fileName: string): Diagnostic[];
+        getSuggestionDiagnostics(fileName: string): DiagnosticWithLocation[];
 
         // TODO: Rename this to getProgramDiagnostics to better indicate that these are any
         // diagnostics present for the program level, and not just 'options' diagnostics.
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index cbf39a2a48f5c..e5ac29026ce46 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -1734,9 +1734,10 @@ declare namespace ts {
         emit(targetSourceFile?: SourceFile, writeFile?: WriteFileCallback, cancellationToken?: CancellationToken, emitOnlyDtsFiles?: boolean, customTransformers?: CustomTransformers): EmitResult;
         getOptionsDiagnostics(cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
         getGlobalDiagnostics(cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
-        getSyntacticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
+        getSyntacticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<DiagnosticWithLocation>;
+        /** The first time this is called, it will return global diagnostics (no location). */
         getSemanticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
-        getDeclarationDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
+        getDeclarationDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<DiagnosticWithLocation>;
         getConfigFileParsingDiagnostics(): ReadonlyArray<Diagnostic>;
         /**
          * Gets a type checker that can be used to semantically analyze source files in the program.
@@ -2359,6 +2360,11 @@ declare namespace ts {
         code: number;
         source?: string;
     }
+    interface DiagnosticWithLocation extends Diagnostic {
+        file: SourceFile;
+        start: number;
+        length: number;
+    }
     enum DiagnosticCategory {
         Warning = 0,
         Error = 1,
@@ -2754,7 +2760,7 @@ declare namespace ts {
         /** Gets the transformed source files. */
         transformed: T[];
         /** Gets diagnostics for the transformation. */
-        diagnostics?: Diagnostic[];
+        diagnostics?: DiagnosticWithLocation[];
         /**
          * Gets a substitute for a node, if one is available; otherwise, returns the original node.
          *
@@ -2960,7 +2966,7 @@ declare namespace ts {
 }
 declare namespace ts {
     function isExternalModuleNameRelative(moduleName: string): boolean;
-    function sortAndDeduplicateDiagnostics(diagnostics: ReadonlyArray<Diagnostic>): Diagnostic[];
+    function sortAndDeduplicateDiagnostics<T extends Diagnostic>(diagnostics: ReadonlyArray<T>): T[];
 }
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;
@@ -4497,9 +4503,10 @@ declare namespace ts {
     }
     interface LanguageService {
         cleanupSemanticCache(): void;
-        getSyntacticDiagnostics(fileName: string): Diagnostic[];
+        getSyntacticDiagnostics(fileName: string): DiagnosticWithLocation[];
+        /** The first time this is called, it will return global diagnostics (no location). */
         getSemanticDiagnostics(fileName: string): Diagnostic[];
-        getSuggestionDiagnostics(fileName: string): Diagnostic[];
+        getSuggestionDiagnostics(fileName: string): DiagnosticWithLocation[];
         getCompilerOptionsDiagnostics(): Diagnostic[];
         /**
          * @deprecated Use getEncodedSyntacticClassifications instead.
@@ -8127,7 +8134,6 @@ declare namespace ts.server {
         syntaxOnly?: boolean;
     }
     class ProjectService {
-        private readonly documentRegistry;
         /**
          * Container of all known scripts
          */
@@ -8176,7 +8182,7 @@ declare namespace ts.server {
         private safelist;
         private legacySafelist;
         private pendingProjectUpdates;
-        readonly currentDirectory: string;
+        readonly currentDirectory: NormalizedPath;
         readonly toCanonicalFileName: (f: string) => string;
         readonly host: ServerHost;
         readonly logger: Logger;
@@ -8391,6 +8397,7 @@ declare namespace ts.server {
         suppressDiagnosticEvents?: boolean;
         syntaxOnly?: boolean;
         throttleWaitMilliseconds?: number;
+        noGetErrOnBackgroundUpdate?: boolean;
         globalPlugins?: ReadonlyArray<string>;
         pluginProbeLocations?: ReadonlyArray<string>;
         allowLocalPluginLoads?: boolean;
@@ -8410,6 +8417,7 @@ declare namespace ts.server {
         protected canUseEvents: boolean;
         private suppressDiagnosticEvents?;
         private eventHandler;
+        private readonly noGetErrOnBackgroundUpdate?;
         constructor(opts: SessionOptions);
         private sendRequestCompletedEvent;
         private defaultEventHandler;
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index b449fc853c6fb..2ac57dfce79f2 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -1734,9 +1734,10 @@ declare namespace ts {
         emit(targetSourceFile?: SourceFile, writeFile?: WriteFileCallback, cancellationToken?: CancellationToken, emitOnlyDtsFiles?: boolean, customTransformers?: CustomTransformers): EmitResult;
         getOptionsDiagnostics(cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
         getGlobalDiagnostics(cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
-        getSyntacticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
+        getSyntacticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<DiagnosticWithLocation>;
+        /** The first time this is called, it will return global diagnostics (no location). */
         getSemanticDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
-        getDeclarationDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<Diagnostic>;
+        getDeclarationDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): ReadonlyArray<DiagnosticWithLocation>;
         getConfigFileParsingDiagnostics(): ReadonlyArray<Diagnostic>;
         /**
          * Gets a type checker that can be used to semantically analyze source files in the program.
@@ -2359,6 +2360,11 @@ declare namespace ts {
         code: number;
         source?: string;
     }
+    interface DiagnosticWithLocation extends Diagnostic {
+        file: SourceFile;
+        start: number;
+        length: number;
+    }
     enum DiagnosticCategory {
         Warning = 0,
         Error = 1,
@@ -2754,7 +2760,7 @@ declare namespace ts {
         /** Gets the transformed source files. */
         transformed: T[];
         /** Gets diagnostics for the transformation. */
-        diagnostics?: Diagnostic[];
+        diagnostics?: DiagnosticWithLocation[];
         /**
          * Gets a substitute for a node, if one is available; otherwise, returns the original node.
          *
@@ -2960,7 +2966,7 @@ declare namespace ts {
 }
 declare namespace ts {
     function isExternalModuleNameRelative(moduleName: string): boolean;
-    function sortAndDeduplicateDiagnostics(diagnostics: ReadonlyArray<Diagnostic>): Diagnostic[];
+    function sortAndDeduplicateDiagnostics<T extends Diagnostic>(diagnostics: ReadonlyArray<T>): T[];
 }
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;
@@ -4497,9 +4503,10 @@ declare namespace ts {
     }
     interface LanguageService {
         cleanupSemanticCache(): void;
-        getSyntacticDiagnostics(fileName: string): Diagnostic[];
+        getSyntacticDiagnostics(fileName: string): DiagnosticWithLocation[];
+        /** The first time this is called, it will return global diagnostics (no location). */
         getSemanticDiagnostics(fileName: string): Diagnostic[];
-        getSuggestionDiagnostics(fileName: string): Diagnostic[];
+        getSuggestionDiagnostics(fileName: string): DiagnosticWithLocation[];
         getCompilerOptionsDiagnostics(): Diagnostic[];
         /**
          * @deprecated Use getEncodedSyntacticClassifications instead.
diff --git a/tests/baselines/reference/assignmentLHSIsValue.errors.txt b/tests/baselines/reference/assignmentLHSIsValue.errors.txt
index 01de8d33441a5..3064d713a122a 100644
--- a/tests/baselines/reference/assignmentLHSIsValue.errors.txt
+++ b/tests/baselines/reference/assignmentLHSIsValue.errors.txt
@@ -13,7 +13,6 @@ tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(2
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(30,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(31,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(32,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
-tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(35,3): error TS7028: Unused label.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(35,9): error TS1128: Declaration or statement expected.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(38,2): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(38,6): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
@@ -39,7 +38,7 @@ tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(6
 tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(70,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 
 
-==== tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts (39 errors) ====
+==== tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts (38 errors) ====
     // expected error for all the LHS of assignments
     var value: any;
     
@@ -105,8 +104,6 @@ tests/cases/conformance/expressions/assignmentOperator/assignmentLHSIsValue.ts(7
     
     // object literals
     { a: 0} = value;
-      ~
-!!! error TS7028: Unused label.
             ~
 !!! error TS1128: Declaration or statement expected.
     
diff --git a/tests/baselines/reference/bestCommonTypeOfConditionalExpressions2.types b/tests/baselines/reference/bestCommonTypeOfConditionalExpressions2.types
index 997f4ea52492d..ad09c274c9ba6 100644
--- a/tests/baselines/reference/bestCommonTypeOfConditionalExpressions2.types
+++ b/tests/baselines/reference/bestCommonTypeOfConditionalExpressions2.types
@@ -30,7 +30,7 @@ var derived2: Derived2;
 
 var r2 = true ? 1 : '';
 >r2 : string | number
->true ? 1 : '' : 1 | ""
+>true ? 1 : '' : "" | 1
 >true : true
 >1 : 1
 >'' : ""
diff --git a/tests/baselines/reference/blockScopedBindingUsedBeforeDef.errors.txt b/tests/baselines/reference/blockScopedBindingUsedBeforeDef.errors.txt
index 55b5c9dab2d21..3a55ebbfded50 100644
--- a/tests/baselines/reference/blockScopedBindingUsedBeforeDef.errors.txt
+++ b/tests/baselines/reference/blockScopedBindingUsedBeforeDef.errors.txt
@@ -1,10 +1,9 @@
 tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(2,12): error TS2448: Block-scoped variable 'a' used before its declaration.
 tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(5,12): error TS2448: Block-scoped variable 'a' used before its declaration.
-tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(5,35): error TS7027: Unreachable code detected.
 tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(8,7): error TS2448: Block-scoped variable 'b' used before its declaration.
 
 
-==== tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts (4 errors) ====
+==== tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts (3 errors) ====
     // 1:
     for (let {[a]: a} of [{ }]) continue;
                ~
@@ -14,8 +13,6 @@ tests/cases/compiler/blockScopedBindingUsedBeforeDef.ts(8,7): error TS2448: Bloc
     for (let {[a]: a} = { }; false; ) continue;
                ~
 !!! error TS2448: Block-scoped variable 'a' used before its declaration.
-                                      ~~~~~~~~
-!!! error TS7027: Unreachable code detected.
     
     // 3:
     let {[b]: b} = { };
diff --git a/tests/baselines/reference/callExpressionWithTypeParameterConstrainedToOuterTypeParameter.types b/tests/baselines/reference/callExpressionWithTypeParameterConstrainedToOuterTypeParameter.types
index 69188eacd1a1c..76b8a51370261 100644
--- a/tests/baselines/reference/callExpressionWithTypeParameterConstrainedToOuterTypeParameter.types
+++ b/tests/baselines/reference/callExpressionWithTypeParameterConstrainedToOuterTypeParameter.types
@@ -15,7 +15,7 @@ var i: I<string>;
 >I : I<T>
 
 var y = i(""); // y should be string
->y : string
+>y : ""
 >i("") : ""
 >i : I<string>
 >"" : ""
diff --git a/tests/baselines/reference/cf.errors.txt b/tests/baselines/reference/cf.errors.txt
index 75b285c37c647..8f5f82f816962 100644
--- a/tests/baselines/reference/cf.errors.txt
+++ b/tests/baselines/reference/cf.errors.txt
@@ -53,7 +53,7 @@ tests/cases/compiler/cf.ts(36,13): error TS7027: Unreachable code detected.
         }
         catch (e) {
             x++;
-        }    
+        }
         finally {
             x+=3;
         }
diff --git a/tests/baselines/reference/cf.js b/tests/baselines/reference/cf.js
index bc7e43a371ae2..7e95dca1944cc 100644
--- a/tests/baselines/reference/cf.js
+++ b/tests/baselines/reference/cf.js
@@ -39,7 +39,7 @@ function f() {
     }
     catch (e) {
         x++;
-    }    
+    }
     finally {
         x+=3;
     }
diff --git a/tests/baselines/reference/cf.symbols b/tests/baselines/reference/cf.symbols
index 9c2d73f513429..d1f1c8392d1f8 100644
--- a/tests/baselines/reference/cf.symbols
+++ b/tests/baselines/reference/cf.symbols
@@ -77,7 +77,7 @@ function f() {
 
         x++;
 >x : Symbol(x, Decl(cf.ts, 2, 7))
-    }    
+    }
     finally {
         x+=3;
 >x : Symbol(x, Decl(cf.ts, 2, 7))
diff --git a/tests/baselines/reference/cf.types b/tests/baselines/reference/cf.types
index b1b5b74c2f6a1..ba71e388dbdf1 100644
--- a/tests/baselines/reference/cf.types
+++ b/tests/baselines/reference/cf.types
@@ -121,7 +121,7 @@ function f() {
         x++;
 >x++ : number
 >x : number
-    }    
+    }
     finally {
         x+=3;
 >x+=3 : number
diff --git a/tests/baselines/reference/compoundExponentiationAssignmentLHSIsValue.errors.txt b/tests/baselines/reference/compoundExponentiationAssignmentLHSIsValue.errors.txt
index 51b69f81620b9..3f806e2c1fd1b 100644
--- a/tests/baselines/reference/compoundExponentiationAssignmentLHSIsValue.errors.txt
+++ b/tests/baselines/reference/compoundExponentiationAssignmentLHSIsValue.errors.txt
@@ -14,7 +14,6 @@ tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignm
 tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(38,1): error TS2364: The left-hand side of an assignment expression must be a variable or a property access.
 tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(39,1): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(40,1): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
-tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(43,3): error TS7028: Unused label.
 tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(43,10): error TS1128: Declaration or statement expected.
 tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(46,1): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
 tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(52,15): error TS1034: 'super' must be followed by an argument list or member access.
@@ -40,7 +39,7 @@ tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignm
 tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts(85,1): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number' or an enum type.
 
 
-==== tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts (40 errors) ====
+==== tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts (39 errors) ====
     // expected error for all the LHS of compound assignments (arithmetic and addition)
     var value: any;
     
@@ -116,8 +115,6 @@ tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignm
     
     // object literals
     { a: 0 } **= value;
-      ~
-!!! error TS7028: Unused label.
              ~~~
 !!! error TS1128: Declaration or statement expected.
     
diff --git a/tests/baselines/reference/conditionalExpression1.types b/tests/baselines/reference/conditionalExpression1.types
index d5695b64c3860..b5e177b4c7805 100644
--- a/tests/baselines/reference/conditionalExpression1.types
+++ b/tests/baselines/reference/conditionalExpression1.types
@@ -1,8 +1,8 @@
 === tests/cases/compiler/conditionalExpression1.ts ===
 var x: boolean = (true ? 1 : ""); // should be an error
 >x : boolean
->(true ? 1 : "") : 1 | ""
->true ? 1 : "" : 1 | ""
+>(true ? 1 : "") : "" | 1
+>true ? 1 : "" : "" | 1
 >true : true
 >1 : 1
 >"" : ""
diff --git a/tests/baselines/reference/conditionalExpressions2.types b/tests/baselines/reference/conditionalExpressions2.types
index 325a281738faf..3067f212f3c10 100644
--- a/tests/baselines/reference/conditionalExpressions2.types
+++ b/tests/baselines/reference/conditionalExpressions2.types
@@ -15,7 +15,7 @@ var b = false ? undefined : 0;
 
 var c = false ? 1 : 0;
 >c : number
->false ? 1 : 0 : 1 | 0
+>false ? 1 : 0 : 0 | 1
 >false : false
 >1 : 1
 >0 : 0
diff --git a/tests/baselines/reference/conditionalOperatorWithIdenticalBCT.types b/tests/baselines/reference/conditionalOperatorWithIdenticalBCT.types
index a9767c72fc7cd..6f7a4db20e2d1 100644
--- a/tests/baselines/reference/conditionalOperatorWithIdenticalBCT.types
+++ b/tests/baselines/reference/conditionalOperatorWithIdenticalBCT.types
@@ -218,7 +218,7 @@ var result10: (t: X) => any = true ? (m) => m.propertyX1 : (n) => n.propertyX2;
 //Expr1 and Expr2 are literals
 var result11: any = true ? 1 : 'string';
 >result11 : any
->true ? 1 : 'string' : 1 | "string"
+>true ? 1 : 'string' : "string" | 1
 >true : true
 >1 : 1
 >'string' : "string"
diff --git a/tests/baselines/reference/conditionalTypes1.types b/tests/baselines/reference/conditionalTypes1.types
index 699808c1f7823..5b0cb6dd8383a 100644
--- a/tests/baselines/reference/conditionalTypes1.types
+++ b/tests/baselines/reference/conditionalTypes1.types
@@ -589,8 +589,8 @@ function zeroOf<T extends number | string | boolean>(value: T) {
 ><ZeroOf<T>>(typeof value === "number" ? 0 : typeof value === "string" ? "" : false) : ZeroOf<T>
 >ZeroOf : ZeroOf<T>
 >T : T
->(typeof value === "number" ? 0 : typeof value === "string" ? "" : false) : false | 0 | ""
->typeof value === "number" ? 0 : typeof value === "string" ? "" : false : false | 0 | ""
+>(typeof value === "number" ? 0 : typeof value === "string" ? "" : false) : false | "" | 0
+>typeof value === "number" ? 0 : typeof value === "string" ? "" : false : false | "" | 0
 >typeof value === "number" : boolean
 >typeof value : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
 >value : T
diff --git a/tests/baselines/reference/constDeclarations-scopes.errors.txt b/tests/baselines/reference/constDeclarations-scopes.errors.txt
index 064ad9aaaf838..647807a6a3d51 100644
--- a/tests/baselines/reference/constDeclarations-scopes.errors.txt
+++ b/tests/baselines/reference/constDeclarations-scopes.errors.txt
@@ -1,9 +1,7 @@
-tests/cases/compiler/constDeclarations-scopes.ts(12,5): error TS7027: Unreachable code detected.
-tests/cases/compiler/constDeclarations-scopes.ts(21,1): error TS7027: Unreachable code detected.
 tests/cases/compiler/constDeclarations-scopes.ts(27,1): error TS2410: The 'with' statement is not supported. All symbols in a 'with' block will have type 'any'.
 
 
-==== tests/cases/compiler/constDeclarations-scopes.ts (3 errors) ====
+==== tests/cases/compiler/constDeclarations-scopes.ts (1 errors) ====
     // global
     const c = "string";
     
@@ -16,8 +14,6 @@ tests/cases/compiler/constDeclarations-scopes.ts(27,1): error TS2410: The 'with'
     }
     else { 
         const c = 0;
-        ~~~~~
-!!! error TS7027: Unreachable code detected.
         n = c;
     }
     
@@ -27,8 +23,6 @@ tests/cases/compiler/constDeclarations-scopes.ts(27,1): error TS2410: The 'with'
     }
     
     do { 
-    ~~
-!!! error TS7027: Unreachable code detected.
        const c = 0;
         n = c;
     } while (true);
diff --git a/tests/baselines/reference/declFileTypeAnnotationParenType.types b/tests/baselines/reference/declFileTypeAnnotationParenType.types
index a73c9bba0a95a..9d8fddb0559af 100644
--- a/tests/baselines/reference/declFileTypeAnnotationParenType.types
+++ b/tests/baselines/reference/declFileTypeAnnotationParenType.types
@@ -24,7 +24,7 @@ var y = [() => new c()];
 var k: (() => c) | string = (() => new c()) || "";
 >k : string | (() => c)
 >c : c
->(() => new c()) || "" : (() => c) | ""
+>(() => new c()) || "" : "" | (() => c)
 >(() => new c()) : () => c
 >() => new c() : () => c
 >new c() : c
diff --git a/tests/baselines/reference/declarationEmitInvalidExport.errors.txt b/tests/baselines/reference/declarationEmitInvalidExport.errors.txt
index 74c8fc6b0a5e1..45612eb4eb4df 100644
--- a/tests/baselines/reference/declarationEmitInvalidExport.errors.txt
+++ b/tests/baselines/reference/declarationEmitInvalidExport.errors.txt
@@ -1,13 +1,10 @@
-tests/cases/compiler/declarationEmitInvalidExport.ts(2,3): error TS7027: Unreachable code detected.
 tests/cases/compiler/declarationEmitInvalidExport.ts(4,30): error TS4081: Exported type alias 'MyClass' has or is using private name 'myClass'.
 tests/cases/compiler/declarationEmitInvalidExport.ts(5,1): error TS1128: Declaration or statement expected.
 
 
-==== tests/cases/compiler/declarationEmitInvalidExport.ts (3 errors) ====
+==== tests/cases/compiler/declarationEmitInvalidExport.ts (2 errors) ====
     if (false) {
       export var myClass = 0;
-      ~~~~~~
-!!! error TS7027: Unreachable code detected.
     }
     export type MyClass = typeof myClass;
                                  ~~~~~~~
diff --git a/tests/baselines/reference/derivedClassSuperCallsInNonConstructorMembers.errors.txt b/tests/baselines/reference/derivedClassSuperCallsInNonConstructorMembers.errors.txt
index 1e471f9970c1c..fbf03bd2f231a 100644
--- a/tests/baselines/reference/derivedClassSuperCallsInNonConstructorMembers.errors.txt
+++ b/tests/baselines/reference/derivedClassSuperCallsInNonConstructorMembers.errors.txt
@@ -10,7 +10,6 @@ tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassS
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(12,13): error TS1005: ';' expected.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(13,9): error TS2337: Super calls are not permitted outside constructors or in nested functions inside constructors.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(16,5): error TS2304: Cannot find name 'set'.
-tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(16,5): error TS7027: Unreachable code detected.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(16,9): error TS1005: ';' expected.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(16,9): error TS2304: Cannot find name 'C'.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(16,11): error TS2304: Cannot find name 'v'.
@@ -38,7 +37,7 @@ tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassS
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts(31,1): error TS1128: Declaration or statement expected.
 
 
-==== tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts (38 errors) ====
+==== tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassSuperCallsInNonConstructorMembers.ts (37 errors) ====
     // error to use super calls outside a constructor
     
     class Base {
@@ -79,8 +78,6 @@ tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassS
         set C(v) {
         ~~~
 !!! error TS2304: Cannot find name 'set'.
-        ~~~
-!!! error TS7027: Unreachable code detected.
             ~
 !!! error TS1005: ';' expected.
             ~
diff --git a/tests/baselines/reference/invalidContinueInDownlevelAsync.errors.txt b/tests/baselines/reference/invalidContinueInDownlevelAsync.errors.txt
index ffdfee20090d5..f22d84f377996 100644
--- a/tests/baselines/reference/invalidContinueInDownlevelAsync.errors.txt
+++ b/tests/baselines/reference/invalidContinueInDownlevelAsync.errors.txt
@@ -1,8 +1,7 @@
 tests/cases/compiler/invalidContinueInDownlevelAsync.ts(3,9): error TS1107: Jump target cannot cross function boundary.
-tests/cases/compiler/invalidContinueInDownlevelAsync.ts(6,9): error TS7027: Unreachable code detected.
 
 
-==== tests/cases/compiler/invalidContinueInDownlevelAsync.ts (2 errors) ====
+==== tests/cases/compiler/invalidContinueInDownlevelAsync.ts (1 errors) ====
     async function func() {
         if (true) {
             continue;
@@ -11,7 +10,5 @@ tests/cases/compiler/invalidContinueInDownlevelAsync.ts(6,9): error TS7027: Unre
         }
         else {
             await 1;
-            ~~~~~
-!!! error TS7027: Unreachable code detected.
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/invalidWhileBreakStatements.errors.txt b/tests/baselines/reference/invalidWhileBreakStatements.errors.txt
index 7d4f86b3e9d15..54adc2856d7ef 100644
--- a/tests/baselines/reference/invalidWhileBreakStatements.errors.txt
+++ b/tests/baselines/reference/invalidWhileBreakStatements.errors.txt
@@ -1,14 +1,12 @@
 tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(4,1): error TS1105: A 'break' statement can only be used within an enclosing iteration or switch statement.
-tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(7,1): error TS7028: Unused label.
 tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(8,14): error TS1116: A 'break' statement can only jump to a label of an enclosing statement.
-tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(11,1): error TS7027: Unreachable code detected.
 tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(14,9): error TS1107: Jump target cannot cross function boundary.
 tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(21,9): error TS1107: Jump target cannot cross function boundary.
 tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(27,5): error TS1116: A 'break' statement can only jump to a label of an enclosing statement.
 tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts(37,5): error TS1116: A 'break' statement can only jump to a label of an enclosing statement.
 
 
-==== tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts (8 errors) ====
+==== tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.ts (6 errors) ====
     // All errors
     
     // naked break not allowed
@@ -18,16 +16,12 @@ tests/cases/conformance/statements/breakStatements/invalidWhileBreakStatements.t
     
     // non-existent label
     ONE:
-    ~~~
-!!! error TS7028: Unused label.
     while (true) break TWO;
                  ~~~~~~~~~~
 !!! error TS1116: A 'break' statement can only jump to a label of an enclosing statement.
     
     // break from inside function
     TWO:
-    ~~~
-!!! error TS7027: Unreachable code detected.
     while (true){
         var x = () => {
             break TWO;
diff --git a/tests/baselines/reference/literalTypeWidening.js b/tests/baselines/reference/literalTypeWidening.js
index 580021235575a..fc805ac670646 100644
--- a/tests/baselines/reference/literalTypeWidening.js
+++ b/tests/baselines/reference/literalTypeWidening.js
@@ -60,6 +60,18 @@ function f5() {
     let v4 = c4;
 }
 
+declare function widening<T>(x: T): T;
+declare function nonWidening<T extends string | number | symbol>(x: T): T;
+
+function f6(cond: boolean) {
+    let x1 = widening('a');
+    let x2 = widening(10);
+    let x3 = widening(cond ? 'a' : 10);
+    let y1 = nonWidening('a');
+    let y2 = nonWidening(10);
+    let y3 = nonWidening(cond ? 'a' : 10);
+}
+
 // Repro from #10898
 
 type FAILURE = "FAILURE";
@@ -95,10 +107,33 @@ type TestEvent = "onmouseover" | "onmouseout";
 
 function onMouseOver(): TestEvent { return "onmouseover"; }
 
-let x = onMouseOver();
+let x = onMouseOver();
+
+// Repro from #23649
+
+export function Set<K extends string>(...keys: K[]): Record<K, true | undefined> {
+  const result = {} as Record<K, true | undefined>
+  keys.forEach(key => result[key] = true)
+  return result
+}
+
+export function keys<K extends string, V>(obj: Record<K, V>): K[] {
+  return Object.keys(obj) as K[]
+}
+
+type Obj = { code: LangCode }
+
+const langCodeSet = Set('fr', 'en', 'es', 'it', 'nl')
+export type LangCode = keyof typeof langCodeSet
+export const langCodes = keys(langCodeSet)
+
+const arr: Obj[] = langCodes.map(code => ({ code }))
+
 
 //// [literalTypeWidening.js]
+"use strict";
 // Widening vs. non-widening literal types
+exports.__esModule = true;
 function f1() {
     var c1 = "hello"; // Widening type "hello"
     var v1 = c1; // Type string
@@ -153,6 +188,14 @@ function f5() {
     var c4 = "foo";
     var v4 = c4;
 }
+function f6(cond) {
+    var x1 = widening('a');
+    var x2 = widening(10);
+    var x3 = widening(cond ? 'a' : 10);
+    var y1 = nonWidening('a');
+    var y2 = nonWidening(10);
+    var y3 = nonWidening(cond ? 'a' : 10);
+}
 var FAILURE = "FAILURE";
 function doWork() {
     return FAILURE;
@@ -172,3 +215,21 @@ if (isSuccess(result)) {
 }
 function onMouseOver() { return "onmouseover"; }
 var x = onMouseOver();
+// Repro from #23649
+function Set() {
+    var keys = [];
+    for (var _i = 0; _i < arguments.length; _i++) {
+        keys[_i] = arguments[_i];
+    }
+    var result = {};
+    keys.forEach(function (key) { return result[key] = true; });
+    return result;
+}
+exports.Set = Set;
+function keys(obj) {
+    return Object.keys(obj);
+}
+exports.keys = keys;
+var langCodeSet = Set('fr', 'en', 'es', 'it', 'nl');
+exports.langCodes = keys(langCodeSet);
+var arr = exports.langCodes.map(function (code) { return ({ code: code }); });
diff --git a/tests/baselines/reference/literalTypeWidening.symbols b/tests/baselines/reference/literalTypeWidening.symbols
index e0da630180eaf..bb5a27026c2ab 100644
--- a/tests/baselines/reference/literalTypeWidening.symbols
+++ b/tests/baselines/reference/literalTypeWidening.symbols
@@ -197,89 +197,206 @@ function f5() {
 >c4 : Symbol(c4, Decl(literalTypeWidening.ts, 57, 9))
 }
 
+declare function widening<T>(x: T): T;
+>widening : Symbol(widening, Decl(literalTypeWidening.ts, 59, 1))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 61, 26))
+>x : Symbol(x, Decl(literalTypeWidening.ts, 61, 29))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 61, 26))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 61, 26))
+
+declare function nonWidening<T extends string | number | symbol>(x: T): T;
+>nonWidening : Symbol(nonWidening, Decl(literalTypeWidening.ts, 61, 38))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 62, 29))
+>x : Symbol(x, Decl(literalTypeWidening.ts, 62, 65))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 62, 29))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 62, 29))
+
+function f6(cond: boolean) {
+>f6 : Symbol(f6, Decl(literalTypeWidening.ts, 62, 74))
+>cond : Symbol(cond, Decl(literalTypeWidening.ts, 64, 12))
+
+    let x1 = widening('a');
+>x1 : Symbol(x1, Decl(literalTypeWidening.ts, 65, 7))
+>widening : Symbol(widening, Decl(literalTypeWidening.ts, 59, 1))
+
+    let x2 = widening(10);
+>x2 : Symbol(x2, Decl(literalTypeWidening.ts, 66, 7))
+>widening : Symbol(widening, Decl(literalTypeWidening.ts, 59, 1))
+
+    let x3 = widening(cond ? 'a' : 10);
+>x3 : Symbol(x3, Decl(literalTypeWidening.ts, 67, 7))
+>widening : Symbol(widening, Decl(literalTypeWidening.ts, 59, 1))
+>cond : Symbol(cond, Decl(literalTypeWidening.ts, 64, 12))
+
+    let y1 = nonWidening('a');
+>y1 : Symbol(y1, Decl(literalTypeWidening.ts, 68, 7))
+>nonWidening : Symbol(nonWidening, Decl(literalTypeWidening.ts, 61, 38))
+
+    let y2 = nonWidening(10);
+>y2 : Symbol(y2, Decl(literalTypeWidening.ts, 69, 7))
+>nonWidening : Symbol(nonWidening, Decl(literalTypeWidening.ts, 61, 38))
+
+    let y3 = nonWidening(cond ? 'a' : 10);
+>y3 : Symbol(y3, Decl(literalTypeWidening.ts, 70, 7))
+>nonWidening : Symbol(nonWidening, Decl(literalTypeWidening.ts, 61, 38))
+>cond : Symbol(cond, Decl(literalTypeWidening.ts, 64, 12))
+}
+
 // Repro from #10898
 
 type FAILURE = "FAILURE";
->FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 59, 1), Decl(literalTypeWidening.ts, 64, 5))
+>FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 71, 1), Decl(literalTypeWidening.ts, 76, 5))
 
 const FAILURE = "FAILURE";
->FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 59, 1), Decl(literalTypeWidening.ts, 64, 5))
+>FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 71, 1), Decl(literalTypeWidening.ts, 76, 5))
 
 type Result<T> = T | FAILURE;
->Result : Symbol(Result, Decl(literalTypeWidening.ts, 64, 26))
->T : Symbol(T, Decl(literalTypeWidening.ts, 66, 12))
->T : Symbol(T, Decl(literalTypeWidening.ts, 66, 12))
->FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 59, 1), Decl(literalTypeWidening.ts, 64, 5))
+>Result : Symbol(Result, Decl(literalTypeWidening.ts, 76, 26))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 78, 12))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 78, 12))
+>FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 71, 1), Decl(literalTypeWidening.ts, 76, 5))
 
 function doWork<T>(): Result<T> {
->doWork : Symbol(doWork, Decl(literalTypeWidening.ts, 66, 29))
->T : Symbol(T, Decl(literalTypeWidening.ts, 68, 16))
->Result : Symbol(Result, Decl(literalTypeWidening.ts, 64, 26))
->T : Symbol(T, Decl(literalTypeWidening.ts, 68, 16))
+>doWork : Symbol(doWork, Decl(literalTypeWidening.ts, 78, 29))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 80, 16))
+>Result : Symbol(Result, Decl(literalTypeWidening.ts, 76, 26))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 80, 16))
 
   return FAILURE;
->FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 59, 1), Decl(literalTypeWidening.ts, 64, 5))
+>FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 71, 1), Decl(literalTypeWidening.ts, 76, 5))
 }
 
 function isSuccess<T>(result: Result<T>): result is T {
->isSuccess : Symbol(isSuccess, Decl(literalTypeWidening.ts, 70, 1))
->T : Symbol(T, Decl(literalTypeWidening.ts, 72, 19))
->result : Symbol(result, Decl(literalTypeWidening.ts, 72, 22))
->Result : Symbol(Result, Decl(literalTypeWidening.ts, 64, 26))
->T : Symbol(T, Decl(literalTypeWidening.ts, 72, 19))
->result : Symbol(result, Decl(literalTypeWidening.ts, 72, 22))
->T : Symbol(T, Decl(literalTypeWidening.ts, 72, 19))
+>isSuccess : Symbol(isSuccess, Decl(literalTypeWidening.ts, 82, 1))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 84, 19))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 84, 22))
+>Result : Symbol(Result, Decl(literalTypeWidening.ts, 76, 26))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 84, 19))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 84, 22))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 84, 19))
 
   return !isFailure(result);
->isFailure : Symbol(isFailure, Decl(literalTypeWidening.ts, 74, 1))
->result : Symbol(result, Decl(literalTypeWidening.ts, 72, 22))
+>isFailure : Symbol(isFailure, Decl(literalTypeWidening.ts, 86, 1))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 84, 22))
 }
 
 function isFailure<T>(result: Result<T>): result is FAILURE {
->isFailure : Symbol(isFailure, Decl(literalTypeWidening.ts, 74, 1))
->T : Symbol(T, Decl(literalTypeWidening.ts, 76, 19))
->result : Symbol(result, Decl(literalTypeWidening.ts, 76, 22))
->Result : Symbol(Result, Decl(literalTypeWidening.ts, 64, 26))
->T : Symbol(T, Decl(literalTypeWidening.ts, 76, 19))
->result : Symbol(result, Decl(literalTypeWidening.ts, 76, 22))
->FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 59, 1), Decl(literalTypeWidening.ts, 64, 5))
+>isFailure : Symbol(isFailure, Decl(literalTypeWidening.ts, 86, 1))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 88, 19))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 88, 22))
+>Result : Symbol(Result, Decl(literalTypeWidening.ts, 76, 26))
+>T : Symbol(T, Decl(literalTypeWidening.ts, 88, 19))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 88, 22))
+>FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 71, 1), Decl(literalTypeWidening.ts, 76, 5))
 
   return result === FAILURE;
->result : Symbol(result, Decl(literalTypeWidening.ts, 76, 22))
->FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 59, 1), Decl(literalTypeWidening.ts, 64, 5))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 88, 22))
+>FAILURE : Symbol(FAILURE, Decl(literalTypeWidening.ts, 71, 1), Decl(literalTypeWidening.ts, 76, 5))
 }
 
 function increment(x: number): number {
->increment : Symbol(increment, Decl(literalTypeWidening.ts, 78, 1))
->x : Symbol(x, Decl(literalTypeWidening.ts, 80, 19))
+>increment : Symbol(increment, Decl(literalTypeWidening.ts, 90, 1))
+>x : Symbol(x, Decl(literalTypeWidening.ts, 92, 19))
 
   return x + 1;
->x : Symbol(x, Decl(literalTypeWidening.ts, 80, 19))
+>x : Symbol(x, Decl(literalTypeWidening.ts, 92, 19))
 }
 
 let result = doWork<number>();
->result : Symbol(result, Decl(literalTypeWidening.ts, 84, 3))
->doWork : Symbol(doWork, Decl(literalTypeWidening.ts, 66, 29))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 96, 3))
+>doWork : Symbol(doWork, Decl(literalTypeWidening.ts, 78, 29))
 
 if (isSuccess(result)) {
->isSuccess : Symbol(isSuccess, Decl(literalTypeWidening.ts, 70, 1))
->result : Symbol(result, Decl(literalTypeWidening.ts, 84, 3))
+>isSuccess : Symbol(isSuccess, Decl(literalTypeWidening.ts, 82, 1))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 96, 3))
 
   increment(result);
->increment : Symbol(increment, Decl(literalTypeWidening.ts, 78, 1))
->result : Symbol(result, Decl(literalTypeWidening.ts, 84, 3))
+>increment : Symbol(increment, Decl(literalTypeWidening.ts, 90, 1))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 96, 3))
 }
 
 // Repro from #10898
 
 type TestEvent = "onmouseover" | "onmouseout";
->TestEvent : Symbol(TestEvent, Decl(literalTypeWidening.ts, 88, 1))
+>TestEvent : Symbol(TestEvent, Decl(literalTypeWidening.ts, 100, 1))
 
 function onMouseOver(): TestEvent { return "onmouseover"; }
->onMouseOver : Symbol(onMouseOver, Decl(literalTypeWidening.ts, 92, 46))
->TestEvent : Symbol(TestEvent, Decl(literalTypeWidening.ts, 88, 1))
+>onMouseOver : Symbol(onMouseOver, Decl(literalTypeWidening.ts, 104, 46))
+>TestEvent : Symbol(TestEvent, Decl(literalTypeWidening.ts, 100, 1))
 
 let x = onMouseOver();
->x : Symbol(x, Decl(literalTypeWidening.ts, 96, 3))
->onMouseOver : Symbol(onMouseOver, Decl(literalTypeWidening.ts, 92, 46))
+>x : Symbol(x, Decl(literalTypeWidening.ts, 108, 3))
+>onMouseOver : Symbol(onMouseOver, Decl(literalTypeWidening.ts, 104, 46))
+
+// Repro from #23649
+
+export function Set<K extends string>(...keys: K[]): Record<K, true | undefined> {
+>Set : Symbol(Set, Decl(literalTypeWidening.ts, 108, 22))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 112, 20))
+>keys : Symbol(keys, Decl(literalTypeWidening.ts, 112, 38))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 112, 20))
+>Record : Symbol(Record, Decl(lib.d.ts, --, --))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 112, 20))
+
+  const result = {} as Record<K, true | undefined>
+>result : Symbol(result, Decl(literalTypeWidening.ts, 113, 7))
+>Record : Symbol(Record, Decl(lib.d.ts, --, --))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 112, 20))
+
+  keys.forEach(key => result[key] = true)
+>keys.forEach : Symbol(Array.forEach, Decl(lib.d.ts, --, --))
+>keys : Symbol(keys, Decl(literalTypeWidening.ts, 112, 38))
+>forEach : Symbol(Array.forEach, Decl(lib.d.ts, --, --))
+>key : Symbol(key, Decl(literalTypeWidening.ts, 114, 15))
+>result : Symbol(result, Decl(literalTypeWidening.ts, 113, 7))
+>key : Symbol(key, Decl(literalTypeWidening.ts, 114, 15))
+
+  return result
+>result : Symbol(result, Decl(literalTypeWidening.ts, 113, 7))
+}
+
+export function keys<K extends string, V>(obj: Record<K, V>): K[] {
+>keys : Symbol(keys, Decl(literalTypeWidening.ts, 116, 1))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 118, 21))
+>V : Symbol(V, Decl(literalTypeWidening.ts, 118, 38))
+>obj : Symbol(obj, Decl(literalTypeWidening.ts, 118, 42))
+>Record : Symbol(Record, Decl(lib.d.ts, --, --))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 118, 21))
+>V : Symbol(V, Decl(literalTypeWidening.ts, 118, 38))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 118, 21))
+
+  return Object.keys(obj) as K[]
+>Object.keys : Symbol(ObjectConstructor.keys, Decl(lib.d.ts, --, --))
+>Object : Symbol(Object, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>keys : Symbol(ObjectConstructor.keys, Decl(lib.d.ts, --, --))
+>obj : Symbol(obj, Decl(literalTypeWidening.ts, 118, 42))
+>K : Symbol(K, Decl(literalTypeWidening.ts, 118, 21))
+}
+
+type Obj = { code: LangCode }
+>Obj : Symbol(Obj, Decl(literalTypeWidening.ts, 120, 1))
+>code : Symbol(code, Decl(literalTypeWidening.ts, 122, 12))
+>LangCode : Symbol(LangCode, Decl(literalTypeWidening.ts, 124, 53))
+
+const langCodeSet = Set('fr', 'en', 'es', 'it', 'nl')
+>langCodeSet : Symbol(langCodeSet, Decl(literalTypeWidening.ts, 124, 5))
+>Set : Symbol(Set, Decl(literalTypeWidening.ts, 108, 22))
+
+export type LangCode = keyof typeof langCodeSet
+>LangCode : Symbol(LangCode, Decl(literalTypeWidening.ts, 124, 53))
+>langCodeSet : Symbol(langCodeSet, Decl(literalTypeWidening.ts, 124, 5))
+
+export const langCodes = keys(langCodeSet)
+>langCodes : Symbol(langCodes, Decl(literalTypeWidening.ts, 126, 12))
+>keys : Symbol(keys, Decl(literalTypeWidening.ts, 116, 1))
+>langCodeSet : Symbol(langCodeSet, Decl(literalTypeWidening.ts, 124, 5))
+
+const arr: Obj[] = langCodes.map(code => ({ code }))
+>arr : Symbol(arr, Decl(literalTypeWidening.ts, 128, 5))
+>Obj : Symbol(Obj, Decl(literalTypeWidening.ts, 120, 1))
+>langCodes.map : Symbol(Array.map, Decl(lib.d.ts, --, --))
+>langCodes : Symbol(langCodes, Decl(literalTypeWidening.ts, 126, 12))
+>map : Symbol(Array.map, Decl(lib.d.ts, --, --))
+>code : Symbol(code, Decl(literalTypeWidening.ts, 128, 33))
+>code : Symbol(code, Decl(literalTypeWidening.ts, 128, 43))
 
diff --git a/tests/baselines/reference/literalTypeWidening.types b/tests/baselines/reference/literalTypeWidening.types
index db5df6ba90c7c..7d41472496a41 100644
--- a/tests/baselines/reference/literalTypeWidening.types
+++ b/tests/baselines/reference/literalTypeWidening.types
@@ -219,6 +219,67 @@ function f5() {
 >c4 : "foo"
 }
 
+declare function widening<T>(x: T): T;
+>widening : <T>(x: T) => T
+>T : T
+>x : T
+>T : T
+>T : T
+
+declare function nonWidening<T extends string | number | symbol>(x: T): T;
+>nonWidening : <T extends string | number | symbol>(x: T) => T
+>T : T
+>x : T
+>T : T
+>T : T
+
+function f6(cond: boolean) {
+>f6 : (cond: boolean) => void
+>cond : boolean
+
+    let x1 = widening('a');
+>x1 : string
+>widening('a') : "a"
+>widening : <T>(x: T) => T
+>'a' : "a"
+
+    let x2 = widening(10);
+>x2 : number
+>widening(10) : 10
+>widening : <T>(x: T) => T
+>10 : 10
+
+    let x3 = widening(cond ? 'a' : 10);
+>x3 : string | number
+>widening(cond ? 'a' : 10) : "a" | 10
+>widening : <T>(x: T) => T
+>cond ? 'a' : 10 : "a" | 10
+>cond : boolean
+>'a' : "a"
+>10 : 10
+
+    let y1 = nonWidening('a');
+>y1 : "a"
+>nonWidening('a') : "a"
+>nonWidening : <T extends string | number | symbol>(x: T) => T
+>'a' : "a"
+
+    let y2 = nonWidening(10);
+>y2 : 10
+>nonWidening(10) : 10
+>nonWidening : <T extends string | number | symbol>(x: T) => T
+>10 : 10
+
+    let y3 = nonWidening(cond ? 'a' : 10);
+>y3 : "a" | 10
+>nonWidening(cond ? 'a' : 10) : "a" | 10
+>nonWidening : <T extends string | number | symbol>(x: T) => T
+>cond ? 'a' : 10 : "a" | 10
+>cond : boolean
+>'a' : "a"
+>10 : 10
+}
+
 // Repro from #10898
 
 type FAILURE = "FAILURE";
@@ -316,3 +377,97 @@ let x = onMouseOver();
 >onMouseOver() : TestEvent
 >onMouseOver : () => TestEvent
 
+// Repro from #23649
+
+export function Set<K extends string>(...keys: K[]): Record<K, true | undefined> {
+>Set : <K extends string>(...keys: K[]) => Record<K, true>
+>K : K
+>keys : K[]
+>K : K
+>Record : Record<K, T>
+>K : K
+>true : true
+
+  const result = {} as Record<K, true | undefined>
+>result : Record<K, true>
+>{} as Record<K, true | undefined> : Record<K, true>
+>{} : {}
+>Record : Record<K, T>
+>K : K
+>true : true
+
+  keys.forEach(key => result[key] = true)
+>keys.forEach(key => result[key] = true) : void
+>keys.forEach : (callbackfn: (value: K, index: number, array: K[]) => void, thisArg?: any) => void
+>keys : K[]
+>forEach : (callbackfn: (value: K, index: number, array: K[]) => void, thisArg?: any) => void
+>key => result[key] = true : (key: K) => boolean
+>key : K
+>result[key] = true : true
+>result[key] : Record<K, true>[K]
+>result : Record<K, true>
+>key : K
+>true : true
+
+  return result
+>result : Record<K, true>
+}
+
+export function keys<K extends string, V>(obj: Record<K, V>): K[] {
+>keys : <K extends string, V>(obj: Record<K, V>) => K[]
+>K : K
+>V : V
+>obj : Record<K, V>
+>Record : Record<K, T>
+>K : K
+>V : V
+>K : K
+
+  return Object.keys(obj) as K[]
+>Object.keys(obj) as K[] : K[]
+>Object.keys(obj) : string[]
+>Object.keys : (o: {}) => string[]
+>Object : ObjectConstructor
+>keys : (o: {}) => string[]
+>obj : Record<K, V>
+>K : K
+}
+
+type Obj = { code: LangCode }
+>Obj : Obj
+>code : "fr" | "en" | "es" | "it" | "nl"
+>LangCode : "fr" | "en" | "es" | "it" | "nl"
+
+const langCodeSet = Set('fr', 'en', 'es', 'it', 'nl')
+>langCodeSet : Record<"fr" | "en" | "es" | "it" | "nl", true>
+>Set('fr', 'en', 'es', 'it', 'nl') : Record<"fr" | "en" | "es" | "it" | "nl", true>
+>Set : <K extends string>(...keys: K[]) => Record<K, true>
+>'fr' : "fr"
+>'en' : "en"
+>'es' : "es"
+>'it' : "it"
+>'nl' : "nl"
+
+export type LangCode = keyof typeof langCodeSet
+>LangCode : "fr" | "en" | "es" | "it" | "nl"
+>langCodeSet : Record<"fr" | "en" | "es" | "it" | "nl", true>
+
+export const langCodes = keys(langCodeSet)
+>langCodes : ("fr" | "en" | "es" | "it" | "nl")[]
+>keys(langCodeSet) : ("fr" | "en" | "es" | "it" | "nl")[]
+>keys : <K extends string, V>(obj: Record<K, V>) => K[]
+>langCodeSet : Record<"fr" | "en" | "es" | "it" | "nl", true>
+
+const arr: Obj[] = langCodes.map(code => ({ code }))
+>arr : Obj[]
+>Obj : Obj
+>langCodes.map(code => ({ code })) : { code: "fr" | "en" | "es" | "it" | "nl"; }[]
+>langCodes.map : <U>(callbackfn: (value: "fr" | "en" | "es" | "it" | "nl", index: number, array: ("fr" | "en" | "es" | "it" | "nl")[]) => U, thisArg?: any) => U[]
+>langCodes : ("fr" | "en" | "es" | "it" | "nl")[]
+>map : <U>(callbackfn: (value: "fr" | "en" | "es" | "it" | "nl", index: number, array: ("fr" | "en" | "es" | "it" | "nl")[]) => U, thisArg?: any) => U[]
+>code => ({ code }) : (code: "fr" | "en" | "es" | "it" | "nl") => { code: "fr" | "en" | "es" | "it" | "nl"; }
+>code : "fr" | "en" | "es" | "it" | "nl"
+>({ code }) : { code: "fr" | "en" | "es" | "it" | "nl"; }
+>{ code } : { code: "fr" | "en" | "es" | "it" | "nl"; }
+>code : "fr" | "en" | "es" | "it" | "nl"
+
diff --git a/tests/baselines/reference/literalTypes2.types b/tests/baselines/reference/literalTypes2.types
index 429a1457c4e9f..e4e33445790d2 100644
--- a/tests/baselines/reference/literalTypes2.types
+++ b/tests/baselines/reference/literalTypes2.types
@@ -555,7 +555,7 @@ class C2 {
 >bar : () => 1 | 0
 
         return cond ? 0 : 1;
->cond ? 0 : 1 : 1 | 0
+>cond ? 0 : 1 : 0 | 1
 >cond : boolean
 >0 : 0
 >1 : 1
diff --git a/tests/baselines/reference/literalTypes3.types b/tests/baselines/reference/literalTypes3.types
index 059e2777e541e..c0623dd6523f5 100644
--- a/tests/baselines/reference/literalTypes3.types
+++ b/tests/baselines/reference/literalTypes3.types
@@ -107,7 +107,7 @@ function f5(x: number, y: 1 | 2) {
 >y : 1 | 2
 
         x;  // 0 | 1 | 2
->x : 1 | 2 | 0
+>x : 0 | 1 | 2
     }
 }
 
@@ -126,7 +126,7 @@ function f6(x: number, y: 1 | 2) {
 >x : number
 
         x;  // 0 | 1 | 2
->x : 1 | 2 | 0
+>x : 0 | 1 | 2
     }
 }
 
diff --git a/tests/baselines/reference/nestedBlockScopedBindings13.errors.txt b/tests/baselines/reference/nestedBlockScopedBindings13.errors.txt
deleted file mode 100644
index 0421583cff9b2..0000000000000
--- a/tests/baselines/reference/nestedBlockScopedBindings13.errors.txt
+++ /dev/null
@@ -1,18 +0,0 @@
-tests/cases/compiler/nestedBlockScopedBindings13.ts(2,5): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings13.ts(7,5): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/compiler/nestedBlockScopedBindings13.ts (2 errors) ====
-    for (; false;) {
-        let x;
-        ~~~
-!!! error TS7027: Unreachable code detected.
-        () => x;
-    }
-    
-    for (; false;) {
-        let y;
-        ~~~
-!!! error TS7027: Unreachable code detected.
-        y = 1;
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedBlockScopedBindings14.errors.txt b/tests/baselines/reference/nestedBlockScopedBindings14.errors.txt
deleted file mode 100644
index 1b5babb4c25a0..0000000000000
--- a/tests/baselines/reference/nestedBlockScopedBindings14.errors.txt
+++ /dev/null
@@ -1,20 +0,0 @@
-tests/cases/compiler/nestedBlockScopedBindings14.ts(3,5): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings14.ts(9,5): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/compiler/nestedBlockScopedBindings14.ts (2 errors) ====
-    var x;
-    for (; false;) {
-        let x;
-        ~~~
-!!! error TS7027: Unreachable code detected.
-        () => x;
-    }
-    
-    var y;
-    for (; false;) {
-        let y;
-        ~~~
-!!! error TS7027: Unreachable code detected.
-        y = 1;
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedBlockScopedBindings15.errors.txt b/tests/baselines/reference/nestedBlockScopedBindings15.errors.txt
deleted file mode 100644
index b60a502b528d7..0000000000000
--- a/tests/baselines/reference/nestedBlockScopedBindings15.errors.txt
+++ /dev/null
@@ -1,46 +0,0 @@
-tests/cases/compiler/nestedBlockScopedBindings15.ts(3,9): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings15.ts(10,9): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings15.ts(16,5): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings15.ts(25,5): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/compiler/nestedBlockScopedBindings15.ts (4 errors) ====
-    for (; false;) {
-        {
-            let x;
-            ~~~
-!!! error TS7027: Unreachable code detected.
-            () => x;
-        }
-    }
-    
-    for (; false;) {
-        {
-            let y;
-            ~~~
-!!! error TS7027: Unreachable code detected.
-            y = 1;
-        }
-    }
-    
-    for (; false;) {
-        switch (1){
-        ~~~~~~
-!!! error TS7027: Unreachable code detected.
-            case 1:
-                let z0;
-                () => z0;
-                break;
-        }
-    }
-    
-    for (; false;) {
-        switch (1){
-        ~~~~~~
-!!! error TS7027: Unreachable code detected.
-            case 1:
-                let z;
-                z = 1;
-                break;
-        }
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedBlockScopedBindings16.errors.txt b/tests/baselines/reference/nestedBlockScopedBindings16.errors.txt
deleted file mode 100644
index 806f58231a060..0000000000000
--- a/tests/baselines/reference/nestedBlockScopedBindings16.errors.txt
+++ /dev/null
@@ -1,50 +0,0 @@
-tests/cases/compiler/nestedBlockScopedBindings16.ts(4,9): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings16.ts(12,9): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings16.ts(19,5): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings16.ts(29,5): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/compiler/nestedBlockScopedBindings16.ts (4 errors) ====
-    var x;
-    for (; false;) {
-        {
-            let x;
-            ~~~
-!!! error TS7027: Unreachable code detected.
-            () => x;
-        }
-    }
-    
-    var y;
-    for (; false;) {
-        {
-            let y;
-            ~~~
-!!! error TS7027: Unreachable code detected.
-            y = 1;
-        }
-    }
-    
-    var z0;
-    for (; false;) {
-        switch (1){
-        ~~~~~~
-!!! error TS7027: Unreachable code detected.
-            case 1:
-                let z0;
-                () => z0;
-                break;
-        }
-    }
-    
-    var z;
-    for (; false;) {
-        switch (1){
-        ~~~~~~
-!!! error TS7027: Unreachable code detected.
-            case 1:
-                let z;
-                z = 1;
-                break;
-        }
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedBlockScopedBindings5.errors.txt b/tests/baselines/reference/nestedBlockScopedBindings5.errors.txt
deleted file mode 100644
index a40f6a29aead0..0000000000000
--- a/tests/baselines/reference/nestedBlockScopedBindings5.errors.txt
+++ /dev/null
@@ -1,92 +0,0 @@
-tests/cases/compiler/nestedBlockScopedBindings5.ts(37,9): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings5.ts(54,9): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings5.ts(71,9): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/compiler/nestedBlockScopedBindings5.ts (3 errors) ====
-    function a0() {
-        for (let x in []) {
-            x = x + 1;
-        }
-        for (let x;;) {
-            x = x + 2;
-        }
-    }
-    
-    function a1() {
-        for (let x in []) {
-            x = x + 1;
-            () => x;
-        }
-        for (let x;;) {
-            x = x + 2;
-        }
-    }
-    
-    function a2() {
-        for (let x in []) {
-            x = x + 1;
-        }
-        for (let x;;) {
-            x = x + 2;
-            () => x;
-        }
-    }
-    
-    
-    function a3() {
-        for (let x in []) {
-            x = x + 1;
-            () => x;
-        }
-        for (let x;false;) {
-            x = x + 2;
-            ~
-!!! error TS7027: Unreachable code detected.
-            () => x;
-        }
-        switch (1) {
-            case 1:
-                let x;
-                () => x;
-                break;
-        }
-        
-    }
-    
-    function a4() {
-        for (let x in []) {
-            x = x + 1;
-        }
-        for (let x;false;) {
-            x = x + 2;
-            ~
-!!! error TS7027: Unreachable code detected.
-        }
-        switch (1) {
-            case 1:
-                let x;
-                () => x;
-                break;
-        }
-        
-    }
-    
-    function a5() {
-        let y;
-        for (let x in []) {
-            x = x + 1;
-        }
-        for (let x;false;) {
-            x = x + 2;
-            ~
-!!! error TS7027: Unreachable code detected.
-            () => x;
-        }
-        switch (1) {
-            case 1:
-                let x;
-                break;
-        }
-        
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedBlockScopedBindings7.errors.txt b/tests/baselines/reference/nestedBlockScopedBindings7.errors.txt
deleted file mode 100644
index 274ef8bf6c336..0000000000000
--- a/tests/baselines/reference/nestedBlockScopedBindings7.errors.txt
+++ /dev/null
@@ -1,16 +0,0 @@
-tests/cases/compiler/nestedBlockScopedBindings7.ts(2,5): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings7.ts(6,5): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/compiler/nestedBlockScopedBindings7.ts (2 errors) ====
-    for (let x; false;) {
-        () => x;
-        ~
-!!! error TS7027: Unreachable code detected.
-    }
-    
-    for (let y; false;) {
-        y = 1;
-        ~
-!!! error TS7027: Unreachable code detected.
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedBlockScopedBindings8.errors.txt b/tests/baselines/reference/nestedBlockScopedBindings8.errors.txt
deleted file mode 100644
index 73f580ae3cb74..0000000000000
--- a/tests/baselines/reference/nestedBlockScopedBindings8.errors.txt
+++ /dev/null
@@ -1,18 +0,0 @@
-tests/cases/compiler/nestedBlockScopedBindings8.ts(3,5): error TS7027: Unreachable code detected.
-tests/cases/compiler/nestedBlockScopedBindings8.ts(8,5): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/compiler/nestedBlockScopedBindings8.ts (2 errors) ====
-    var x;
-    for (let x; false; ) {
-        () => x;
-        ~
-!!! error TS7027: Unreachable code detected.
-    }
-    
-    var y;
-    for (let y; false; ) {
-        y = 1;
-        ~
-!!! error TS7027: Unreachable code detected.
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/newExpressionWithTypeParameterConstrainedToOuterTypeParameter.types b/tests/baselines/reference/newExpressionWithTypeParameterConstrainedToOuterTypeParameter.types
index badd17765b8d2..6d54119880233 100644
--- a/tests/baselines/reference/newExpressionWithTypeParameterConstrainedToOuterTypeParameter.types
+++ b/tests/baselines/reference/newExpressionWithTypeParameterConstrainedToOuterTypeParameter.types
@@ -15,7 +15,7 @@ var i: I<string>;
 >I : I<T>
 
 var y = new i(""); // y should be string
->y : string
+>y : ""
 >new i("") : ""
 >i : I<string>
 >"" : ""
diff --git a/tests/baselines/reference/organizeImports/JsxFactoryUnusedJs.ts b/tests/baselines/reference/organizeImports/JsxFactoryUnusedJs.ts
new file mode 100644
index 0000000000000..60afb95a19257
--- /dev/null
+++ b/tests/baselines/reference/organizeImports/JsxFactoryUnusedJs.ts
@@ -0,0 +1,6 @@
+// ==ORIGINAL==
+
+import { React, Other } from "react";
+
+// ==ORGANIZED==
+
diff --git a/tests/baselines/reference/organizeImports/JsxFactoryUnusedJsx.ts b/tests/baselines/reference/organizeImports/JsxFactoryUnusedJsx.ts
new file mode 100644
index 0000000000000..60afb95a19257
--- /dev/null
+++ b/tests/baselines/reference/organizeImports/JsxFactoryUnusedJsx.ts
@@ -0,0 +1,6 @@
+// ==ORIGINAL==
+
+import { React, Other } from "react";
+
+// ==ORGANIZED==
+
diff --git a/tests/baselines/reference/organizeImports/JsxFactoryUnusedTsx.ts b/tests/baselines/reference/organizeImports/JsxFactoryUnusedTsx.ts
index 6a97e7f660ae1..60afb95a19257 100644
--- a/tests/baselines/reference/organizeImports/JsxFactoryUnusedTsx.ts
+++ b/tests/baselines/reference/organizeImports/JsxFactoryUnusedTsx.ts
@@ -4,4 +4,3 @@ import { React, Other } from "react";
 
 // ==ORGANIZED==
 
-import { React } from "react";
diff --git a/tests/baselines/reference/organizeImports/JsxFactoryUsed.ts b/tests/baselines/reference/organizeImports/JsxFactoryUsedJs.ts
similarity index 100%
rename from tests/baselines/reference/organizeImports/JsxFactoryUsed.ts
rename to tests/baselines/reference/organizeImports/JsxFactoryUsedJs.ts
diff --git a/tests/baselines/reference/organizeImports/JsxFactoryUsedJsx.ts b/tests/baselines/reference/organizeImports/JsxFactoryUsedJsx.ts
new file mode 100644
index 0000000000000..430a5b12cd4d4
--- /dev/null
+++ b/tests/baselines/reference/organizeImports/JsxFactoryUsedJsx.ts
@@ -0,0 +1,11 @@
+// ==ORIGINAL==
+
+import { React, Other } from "react";
+
+<div/>;
+
+// ==ORGANIZED==
+
+import { React } from "react";
+
+<div/>;
diff --git a/tests/baselines/reference/organizeImports/JsxFactoryUsedTs.ts b/tests/baselines/reference/organizeImports/JsxFactoryUsedTs.ts
new file mode 100644
index 0000000000000..74da2f99139e0
--- /dev/null
+++ b/tests/baselines/reference/organizeImports/JsxFactoryUsedTs.ts
@@ -0,0 +1,10 @@
+// ==ORIGINAL==
+
+import { React, Other } from "react";
+
+<div/>;
+
+// ==ORGANIZED==
+
+
+<div/>;
diff --git a/tests/baselines/reference/organizeImports/JsxFactoryUsedTsx.ts b/tests/baselines/reference/organizeImports/JsxFactoryUsedTsx.ts
new file mode 100644
index 0000000000000..430a5b12cd4d4
--- /dev/null
+++ b/tests/baselines/reference/organizeImports/JsxFactoryUsedTsx.ts
@@ -0,0 +1,11 @@
+// ==ORIGINAL==
+
+import { React, Other } from "react";
+
+<div/>;
+
+// ==ORGANIZED==
+
+import { React } from "react";
+
+<div/>;
diff --git a/tests/baselines/reference/parserArgumentList1.types b/tests/baselines/reference/parserArgumentList1.types
index ddf00ee8750da..3e210b8089078 100644
--- a/tests/baselines/reference/parserArgumentList1.types
+++ b/tests/baselines/reference/parserArgumentList1.types
@@ -26,7 +26,7 @@ export function removeClass (node:HTMLElement, className:string) {
 >rightDelimiter : any
 
 		return leftDelimiter.length + rightDelimiter.length === 2 ? ' ' : '';
->leftDelimiter.length + rightDelimiter.length === 2 ? ' ' : '' : " " | ""
+>leftDelimiter.length + rightDelimiter.length === 2 ? ' ' : '' : "" | " "
 >leftDelimiter.length + rightDelimiter.length === 2 : boolean
 >leftDelimiter.length + rightDelimiter.length : any
 >leftDelimiter.length : any
diff --git a/tests/baselines/reference/parserErrorRecovery_ModuleElement1.errors.txt b/tests/baselines/reference/parserErrorRecovery_ModuleElement1.errors.txt
index 05b31b7af8e56..4b8be3e17ad6e 100644
--- a/tests/baselines/reference/parserErrorRecovery_ModuleElement1.errors.txt
+++ b/tests/baselines/reference/parserErrorRecovery_ModuleElement1.errors.txt
@@ -1,16 +1,13 @@
 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ModuleElements/parserErrorRecovery_ModuleElement1.ts(2,1): error TS1128: Declaration or statement expected.
-tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ModuleElements/parserErrorRecovery_ModuleElement1.ts(3,1): error TS7027: Unreachable code detected.
 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ModuleElements/parserErrorRecovery_ModuleElement1.ts(4,1): error TS1128: Declaration or statement expected.
 
 
-==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ModuleElements/parserErrorRecovery_ModuleElement1.ts (3 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/ModuleElements/parserErrorRecovery_ModuleElement1.ts (2 errors) ====
     return foo;
     }
     ~
 !!! error TS1128: Declaration or statement expected.
     return bar;
-    ~~~~~~
-!!! error TS7027: Unreachable code detected.
     }
     ~
 !!! error TS1128: Declaration or statement expected.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserLabeledStatement1.d.errors.txt b/tests/baselines/reference/parserLabeledStatement1.d.errors.txt
index 2ce51b0bb4c6f..11de61548a366 100644
--- a/tests/baselines/reference/parserLabeledStatement1.d.errors.txt
+++ b/tests/baselines/reference/parserLabeledStatement1.d.errors.txt
@@ -1,14 +1,11 @@
 tests/cases/conformance/parser/ecmascript5/Statements/parserLabeledStatement1.d.ts(1,1): error TS1036: Statements are not allowed in ambient contexts.
-tests/cases/conformance/parser/ecmascript5/Statements/parserLabeledStatement1.d.ts(1,1): error TS7028: Unused label.
 tests/cases/conformance/parser/ecmascript5/Statements/parserLabeledStatement1.d.ts(2,3): error TS2304: Cannot find name 'bar'.
 
 
-==== tests/cases/conformance/parser/ecmascript5/Statements/parserLabeledStatement1.d.ts (3 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/Statements/parserLabeledStatement1.d.ts (2 errors) ====
     foo:
     ~~~
 !!! error TS1036: Statements are not allowed in ambient contexts.
-    ~~~
-!!! error TS7028: Unused label.
       bar();
       ~~~
 !!! error TS2304: Cannot find name 'bar'.
\ No newline at end of file
diff --git a/tests/baselines/reference/parser_breakTarget5.errors.txt b/tests/baselines/reference/parser_breakTarget5.errors.txt
index 5943649c97b45..8221cbebb4c70 100644
--- a/tests/baselines/reference/parser_breakTarget5.errors.txt
+++ b/tests/baselines/reference/parser_breakTarget5.errors.txt
@@ -1,11 +1,8 @@
-tests/cases/conformance/parser/ecmascript5/Statements/BreakStatements/parser_breakTarget5.ts(1,1): error TS7028: Unused label.
 tests/cases/conformance/parser/ecmascript5/Statements/BreakStatements/parser_breakTarget5.ts(5,7): error TS1107: Jump target cannot cross function boundary.
 
 
-==== tests/cases/conformance/parser/ecmascript5/Statements/BreakStatements/parser_breakTarget5.ts (2 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/Statements/BreakStatements/parser_breakTarget5.ts (1 errors) ====
     target:
-    ~~~~~~
-!!! error TS7028: Unused label.
     while (true) {
       function f() {
         while (true) {
diff --git a/tests/baselines/reference/parser_continueNotInIterationStatement4.errors.txt b/tests/baselines/reference/parser_continueNotInIterationStatement4.errors.txt
index 9439225956897..efade17a52a03 100644
--- a/tests/baselines/reference/parser_continueNotInIterationStatement4.errors.txt
+++ b/tests/baselines/reference/parser_continueNotInIterationStatement4.errors.txt
@@ -1,11 +1,8 @@
-tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueNotInIterationStatement4.ts(1,1): error TS7028: Unused label.
 tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueNotInIterationStatement4.ts(4,5): error TS1107: Jump target cannot cross function boundary.
 
 
-==== tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueNotInIterationStatement4.ts (2 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueNotInIterationStatement4.ts (1 errors) ====
     TWO:
-    ~~~
-!!! error TS7028: Unused label.
     while (true){
       var x = () => {
         continue TWO;
diff --git a/tests/baselines/reference/parser_continueTarget5.errors.txt b/tests/baselines/reference/parser_continueTarget5.errors.txt
index b9b1f2edb945d..ffeee7a07b311 100644
--- a/tests/baselines/reference/parser_continueTarget5.errors.txt
+++ b/tests/baselines/reference/parser_continueTarget5.errors.txt
@@ -1,11 +1,8 @@
-tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueTarget5.ts(1,1): error TS7028: Unused label.
 tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueTarget5.ts(5,7): error TS1107: Jump target cannot cross function boundary.
 
 
-==== tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueTarget5.ts (2 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/Statements/ContinueStatements/parser_continueTarget5.ts (1 errors) ====
     target:
-    ~~~~~~
-!!! error TS7028: Unused label.
     while (true) {
       function f() {
         while (true) {
diff --git a/tests/baselines/reference/parser_duplicateLabel1.errors.txt b/tests/baselines/reference/parser_duplicateLabel1.errors.txt
index 95c0ad9a290d5..dee0d5d40e681 100644
--- a/tests/baselines/reference/parser_duplicateLabel1.errors.txt
+++ b/tests/baselines/reference/parser_duplicateLabel1.errors.txt
@@ -1,16 +1,10 @@
-tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel1.ts(1,1): error TS7028: Unused label.
 tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel1.ts(2,1): error TS1114: Duplicate label 'target'.
-tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel1.ts(2,1): error TS7028: Unused label.
 
 
-==== tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel1.ts (3 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel1.ts (1 errors) ====
     target:
-    ~~~~~~
-!!! error TS7028: Unused label.
     target:
     ~~~~~~
 !!! error TS1114: Duplicate label 'target'.
-    ~~~~~~
-!!! error TS7028: Unused label.
     while (true) {
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parser_duplicateLabel2.errors.txt b/tests/baselines/reference/parser_duplicateLabel2.errors.txt
index 6d42b8c34fecf..60a2c2659c3ad 100644
--- a/tests/baselines/reference/parser_duplicateLabel2.errors.txt
+++ b/tests/baselines/reference/parser_duplicateLabel2.errors.txt
@@ -1,18 +1,12 @@
-tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel2.ts(1,1): error TS7028: Unused label.
 tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel2.ts(3,3): error TS1114: Duplicate label 'target'.
-tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel2.ts(3,3): error TS7028: Unused label.
 
 
-==== tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel2.ts (3 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/Statements/LabeledStatements/parser_duplicateLabel2.ts (1 errors) ====
     target:
-    ~~~~~~
-!!! error TS7028: Unused label.
     while (true) {
       target:
       ~~~~~~
 !!! error TS1114: Duplicate label 'target'.
-      ~~~~~~
-!!! error TS7028: Unused label.
       while (true) {
       }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/recursiveLetConst.errors.txt b/tests/baselines/reference/recursiveLetConst.errors.txt
index 88ecb379e5ef8..b02d0819a3f46 100644
--- a/tests/baselines/reference/recursiveLetConst.errors.txt
+++ b/tests/baselines/reference/recursiveLetConst.errors.txt
@@ -3,7 +3,6 @@ tests/cases/compiler/recursiveLetConst.ts(3,12): error TS2448: Block-scoped vari
 tests/cases/compiler/recursiveLetConst.ts(4,11): error TS2448: Block-scoped variable 'y' used before its declaration.
 tests/cases/compiler/recursiveLetConst.ts(5,14): error TS2448: Block-scoped variable 'y1' used before its declaration.
 tests/cases/compiler/recursiveLetConst.ts(6,14): error TS2448: Block-scoped variable 'v' used before its declaration.
-tests/cases/compiler/recursiveLetConst.ts(7,1): error TS7027: Unreachable code detected.
 tests/cases/compiler/recursiveLetConst.ts(7,16): error TS2448: Block-scoped variable 'v' used before its declaration.
 tests/cases/compiler/recursiveLetConst.ts(8,15): error TS2448: Block-scoped variable 'v' used before its declaration.
 tests/cases/compiler/recursiveLetConst.ts(9,15): error TS2448: Block-scoped variable 'v' used before its declaration.
@@ -11,7 +10,7 @@ tests/cases/compiler/recursiveLetConst.ts(10,17): error TS2448: Block-scoped var
 tests/cases/compiler/recursiveLetConst.ts(11,11): error TS2448: Block-scoped variable 'x2' used before its declaration.
 
 
-==== tests/cases/compiler/recursiveLetConst.ts (11 errors) ====
+==== tests/cases/compiler/recursiveLetConst.ts (10 errors) ====
     'use strict'
     let x = x + 1;
             ~
@@ -29,8 +28,6 @@ tests/cases/compiler/recursiveLetConst.ts(11,11): error TS2448: Block-scoped var
                  ~
 !!! error TS2448: Block-scoped variable 'v' used before its declaration.
     for (let [v] = v; ;) { }
-    ~~~
-!!! error TS7027: Unreachable code detected.
                    ~
 !!! error TS2448: Block-scoped variable 'v' used before its declaration.
     for (let v in v) { }
diff --git a/tests/baselines/reference/recursiveNamedLambdaCall.errors.txt b/tests/baselines/reference/recursiveNamedLambdaCall.errors.txt
index 04ddc371ac710..7729d1e780fad 100644
--- a/tests/baselines/reference/recursiveNamedLambdaCall.errors.txt
+++ b/tests/baselines/reference/recursiveNamedLambdaCall.errors.txt
@@ -1,12 +1,11 @@
 tests/cases/compiler/recursiveNamedLambdaCall.ts(3,8): error TS2304: Cannot find name 'top'.
 tests/cases/compiler/recursiveNamedLambdaCall.ts(3,15): error TS2304: Cannot find name 'top'.
-tests/cases/compiler/recursiveNamedLambdaCall.ts(7,6): error TS7027: Unreachable code detected.
 tests/cases/compiler/recursiveNamedLambdaCall.ts(8,7): error TS2304: Cannot find name 'top'.
 tests/cases/compiler/recursiveNamedLambdaCall.ts(10,14): error TS2304: Cannot find name 'setTimeout'.
 tests/cases/compiler/recursiveNamedLambdaCall.ts(14,6): error TS2304: Cannot find name 'detach'.
 
 
-==== tests/cases/compiler/recursiveNamedLambdaCall.ts (6 errors) ====
+==== tests/cases/compiler/recursiveNamedLambdaCall.ts (5 errors) ====
     var promise = function( obj ) {
     	
     		if ( top && top.doScroll ) {
@@ -18,8 +17,6 @@ tests/cases/compiler/recursiveNamedLambdaCall.ts(14,6): error TS2304: Cannot fin
     				if ( false ) {
     
     					try {
-    					~~~
-!!! error TS7027: Unreachable code detected.
     						top.doScroll("left");
     						~~~
 !!! error TS2304: Cannot find name 'top'.
diff --git a/tests/baselines/reference/reservedWords2.errors.txt b/tests/baselines/reference/reservedWords2.errors.txt
index f1d781ed59ed7..0760e1e2566e3 100644
--- a/tests/baselines/reference/reservedWords2.errors.txt
+++ b/tests/baselines/reference/reservedWords2.errors.txt
@@ -15,7 +15,6 @@ tests/cases/compiler/reservedWords2.ts(5,9): error TS2567: Enum declarations can
 tests/cases/compiler/reservedWords2.ts(5,10): error TS1003: Identifier expected.
 tests/cases/compiler/reservedWords2.ts(5,18): error TS1005: '=>' expected.
 tests/cases/compiler/reservedWords2.ts(6,1): error TS2304: Cannot find name 'module'.
-tests/cases/compiler/reservedWords2.ts(6,1): error TS7027: Unreachable code detected.
 tests/cases/compiler/reservedWords2.ts(6,8): error TS1005: ';' expected.
 tests/cases/compiler/reservedWords2.ts(7,11): error TS2300: Duplicate identifier '(Missing)'.
 tests/cases/compiler/reservedWords2.ts(7,11): error TS1005: ':' expected.
@@ -33,7 +32,7 @@ tests/cases/compiler/reservedWords2.ts(10,5): error TS2567: Enum declarations ca
 tests/cases/compiler/reservedWords2.ts(10,6): error TS1003: Identifier expected.
 
 
-==== tests/cases/compiler/reservedWords2.ts (33 errors) ====
+==== tests/cases/compiler/reservedWords2.ts (32 errors) ====
     import while = require("dfdf");
            ~~~~~
 !!! error TS1109: Expression expected.
@@ -74,8 +73,6 @@ tests/cases/compiler/reservedWords2.ts(10,6): error TS1003: Identifier expected.
     module void {}
     ~~~~~~
 !!! error TS2304: Cannot find name 'module'.
-    ~~~~~~
-!!! error TS7027: Unreachable code detected.
            ~~~~
 !!! error TS1005: ';' expected.
     var {while, return} = { while: 1, return: 2 };
diff --git a/tests/baselines/reference/scanner10.1.1-8gs.errors.txt b/tests/baselines/reference/scanner10.1.1-8gs.errors.txt
index 6e75f195c2634..512da96548682 100644
--- a/tests/baselines/reference/scanner10.1.1-8gs.errors.txt
+++ b/tests/baselines/reference/scanner10.1.1-8gs.errors.txt
@@ -1,9 +1,8 @@
 tests/cases/conformance/scanner/ecmascript5/scanner10.1.1-8gs.ts(16,7): error TS2304: Cannot find name 'NotEarlyError'.
-tests/cases/conformance/scanner/ecmascript5/scanner10.1.1-8gs.ts(17,1): error TS7027: Unreachable code detected.
 tests/cases/conformance/scanner/ecmascript5/scanner10.1.1-8gs.ts(17,5): error TS1212: Identifier expected. 'public' is a reserved word in strict mode.
 
 
-==== tests/cases/conformance/scanner/ecmascript5/scanner10.1.1-8gs.ts (3 errors) ====
+==== tests/cases/conformance/scanner/ecmascript5/scanner10.1.1-8gs.ts (2 errors) ====
     /// Copyright (c) 2012 Ecma International.  All rights reserved. 
     /// Ecma International makes this code available under the terms and conditions set
     /// forth on http://hg.ecmascript.org/tests/test262/raw-file/tip/LICENSE (the 
@@ -23,8 +22,6 @@ tests/cases/conformance/scanner/ecmascript5/scanner10.1.1-8gs.ts(17,5): error TS
           ~~~~~~~~~~~~~
 !!! error TS2304: Cannot find name 'NotEarlyError'.
     var public = 1;
-    ~~~
-!!! error TS7027: Unreachable code detected.
         ~~~~~~
 !!! error TS1212: Identifier expected. 'public' is a reserved word in strict mode.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/setterWithReturn.errors.txt b/tests/baselines/reference/setterWithReturn.errors.txt
index a0f04506a710b..deb0fa6fc3257 100644
--- a/tests/baselines/reference/setterWithReturn.errors.txt
+++ b/tests/baselines/reference/setterWithReturn.errors.txt
@@ -1,10 +1,9 @@
 tests/cases/compiler/setterWithReturn.ts(2,16): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
 tests/cases/compiler/setterWithReturn.ts(4,13): error TS2408: Setters cannot return a value.
-tests/cases/compiler/setterWithReturn.ts(7,13): error TS7027: Unreachable code detected.
 tests/cases/compiler/setterWithReturn.ts(7,13): error TS2408: Setters cannot return a value.
 
 
-==== tests/cases/compiler/setterWithReturn.ts (4 errors) ====
+==== tests/cases/compiler/setterWithReturn.ts (3 errors) ====
     class C234 {
         public set p1(arg1) {
                    ~~
@@ -16,8 +15,6 @@ tests/cases/compiler/setterWithReturn.ts(7,13): error TS2408: Setters cannot ret
             }
             else {
                 return 0;
-                ~~~~~~
-!!! error TS7027: Unreachable code detected.
                 ~~~~~~~~~
 !!! error TS2408: Setters cannot return a value.
             }
diff --git a/tests/baselines/reference/sourceMapValidationFor.errors.txt b/tests/baselines/reference/sourceMapValidationFor.errors.txt
index ffc981648d696..75139bcb12dbc 100644
--- a/tests/baselines/reference/sourceMapValidationFor.errors.txt
+++ b/tests/baselines/reference/sourceMapValidationFor.errors.txt
@@ -1,8 +1,7 @@
-tests/cases/compiler/sourceMapValidationFor.ts(20,1): error TS7027: Unreachable code detected.
 tests/cases/compiler/sourceMapValidationFor.ts(32,21): error TS2695: Left side of comma operator is unused and has no side effects.
 
 
-==== tests/cases/compiler/sourceMapValidationFor.ts (2 errors) ====
+==== tests/cases/compiler/sourceMapValidationFor.ts (1 errors) ====
     for (var i = 0; i < 10; i++) {
         WScript.Echo("i: " + i);
     }
@@ -23,8 +22,6 @@ tests/cases/compiler/sourceMapValidationFor.ts(32,21): error TS2695: Left side o
     for (var k = 0;; k++) {
     }
     for (k = 0;; k++)
-    ~~~
-!!! error TS7027: Unreachable code detected.
     {
     }
     for (; k < 10; k++) {
diff --git a/tests/baselines/reference/subtypesOfTypeParameter.types b/tests/baselines/reference/subtypesOfTypeParameter.types
index 58af856e15074..b703292fb4f2b 100644
--- a/tests/baselines/reference/subtypesOfTypeParameter.types
+++ b/tests/baselines/reference/subtypesOfTypeParameter.types
@@ -144,14 +144,14 @@ function f2<T, U>(x: T, y: U) {
 
     var r2 = true ? '' : x;
 >r2 : string | T
->true ? '' : x : T | ""
+>true ? '' : x : "" | T
 >true : true
 >'' : ""
 >x : T
 
     var r2 = true ? x : '';
 >r2 : string | T
->true ? x : '' : T | ""
+>true ? x : '' : "" | T
 >true : true
 >x : T
 >'' : ""
diff --git a/tests/baselines/reference/subtypesOfTypeParameterWithConstraints2.types b/tests/baselines/reference/subtypesOfTypeParameterWithConstraints2.types
index e2f294343a573..34ef257609b60 100644
--- a/tests/baselines/reference/subtypesOfTypeParameterWithConstraints2.types
+++ b/tests/baselines/reference/subtypesOfTypeParameterWithConstraints2.types
@@ -259,14 +259,14 @@ function f6<T extends String>(x: T) {
 
     var r2 = true ? '' : x; // ok
 >r2 : string | T
->true ? '' : x : T | ""
+>true ? '' : x : "" | T
 >true : true
 >'' : ""
 >x : T
 
     var r2 = true ? x : ''; // ok
 >r2 : string | T
->true ? x : '' : T | ""
+>true ? x : '' : "" | T
 >true : true
 >x : T
 >'' : ""
diff --git a/tests/baselines/reference/thisTypeInFunctionsNegative.errors.txt b/tests/baselines/reference/thisTypeInFunctionsNegative.errors.txt
index 56ac090c02c9f..797c6877e21b5 100644
--- a/tests/baselines/reference/thisTypeInFunctionsNegative.errors.txt
+++ b/tests/baselines/reference/thisTypeInFunctionsNegative.errors.txt
@@ -93,13 +93,12 @@ tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(172,39): e
 tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(172,40): error TS1128: Declaration or statement expected.
 tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(172,42): error TS2693: 'number' only refers to a type, but is being used as a value here.
 tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(172,49): error TS1005: ';' expected.
-tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(175,1): error TS7027: Unreachable code detected.
 tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(175,29): error TS2304: Cannot find name 'm'.
 tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(175,32): error TS1005: ';' expected.
 tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(175,35): error TS2304: Cannot find name 'm'.
 
 
-==== tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts (65 errors) ====
+==== tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts (64 errors) ====
     class C {
         n: number;
         explicitThis(this: this, m: number): number {
@@ -431,8 +430,6 @@ tests/cases/conformance/types/thisType/thisTypeInFunctionsNegative.ts(175,35): e
     
     // can't name parameters 'this' in a lambda.
     c.explicitProperty = (this, m) => m + this.n;
-    ~
-!!! error TS7027: Unreachable code detected.
                                 ~
 !!! error TS2304: Cannot find name 'm'.
                                    ~~
diff --git a/tests/baselines/reference/throwWithoutNewLine2.errors.txt b/tests/baselines/reference/throwWithoutNewLine2.errors.txt
index 83f4e4cc24627..6930d240e7b82 100644
--- a/tests/baselines/reference/throwWithoutNewLine2.errors.txt
+++ b/tests/baselines/reference/throwWithoutNewLine2.errors.txt
@@ -1,14 +1,11 @@
 tests/cases/compiler/throwWithoutNewLine2.ts(1,6): error TS1142: Line break not permitted here.
 tests/cases/compiler/throwWithoutNewLine2.ts(2,1): error TS2304: Cannot find name 'a'.
-tests/cases/compiler/throwWithoutNewLine2.ts(2,1): error TS7027: Unreachable code detected.
 
 
-==== tests/cases/compiler/throwWithoutNewLine2.ts (3 errors) ====
+==== tests/cases/compiler/throwWithoutNewLine2.ts (2 errors) ====
     throw
          
 !!! error TS1142: Line break not permitted here.
     a;
     ~
-!!! error TS2304: Cannot find name 'a'.
-    ~
-!!! error TS7027: Unreachable code detected.
\ No newline at end of file
+!!! error TS2304: Cannot find name 'a'.
\ No newline at end of file
diff --git a/tests/baselines/reference/typeGuardFunctionErrors.errors.txt b/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
index 52e8b3bf81bd2..4be44cc799a1a 100644
--- a/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
+++ b/tests/baselines/reference/typeGuardFunctionErrors.errors.txt
@@ -8,7 +8,6 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(21,33)
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(25,33): error TS1225: Cannot find parameter 'x'.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(29,10): error TS2391: Function implementation is missing or not immediately following the declaration.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(30,5): error TS1131: Property or signature expected.
-tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(30,5): error TS7027: Unreachable code detected.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(31,1): error TS1128: Declaration or statement expected.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(33,38): error TS1225: Cannot find parameter 'x'.
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(37,51): error TS2677: A type predicate's type must be assignable to its parameter's type.
@@ -71,7 +70,7 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(166,45
 tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(166,54): error TS2344: Type 'number' does not satisfy the constraint 'Foo'.
 
 
-==== tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts (57 errors) ====
+==== tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts (56 errors) ====
     class A {
           ~
 !!! error TS2300: Duplicate identifier 'A'.
@@ -122,8 +121,6 @@ tests/cases/conformance/expressions/typeGuards/typeGuardFunctionErrors.ts(166,54
         return true;
         ~~~~~~
 !!! error TS1131: Property or signature expected.
-        ~~~~~~
-!!! error TS7027: Unreachable code detected.
     }
     ~
 !!! error TS1128: Declaration or statement expected.
diff --git a/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt b/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt
index 9357cf4e4cc36..4251ce08ad957 100644
--- a/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt
+++ b/tests/baselines/reference/typeofOperatorWithAnyOtherType.errors.txt
@@ -2,16 +2,9 @@ tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperator
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(47,32): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'.
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(48,32): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(58,1): error TS2695: Left side of comma operator is unused and has no side effects.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(68,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(69,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(70,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(71,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(72,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(73,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts(74,1): error TS7028: Unused label.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts (11 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithAnyOtherType.ts (4 errors) ====
     // typeof  operator on any type
     
     var ANY: any;
@@ -88,23 +81,9 @@ tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperator
     var x: any[];
     var r: () => any;
     z: typeof ANY;
-    ~
-!!! error TS7028: Unused label.
     x: typeof ANY2;
-    ~
-!!! error TS7028: Unused label.
     r: typeof foo;
-    ~
-!!! error TS7028: Unused label.
     z: typeof objA.a;
-    ~
-!!! error TS7028: Unused label.
     z: typeof A.foo;
-    ~
-!!! error TS7028: Unused label.
     z: typeof M.n;
-    ~
-!!! error TS7028: Unused label.
-    z: typeof obj1.x;
-    ~
-!!! error TS7028: Unused label.
\ No newline at end of file
+    z: typeof obj1.x;
\ No newline at end of file
diff --git a/tests/baselines/reference/typeofOperatorWithStringType.errors.txt b/tests/baselines/reference/typeofOperatorWithStringType.errors.txt
index 6d01d397ab6c6..1aa3905d1496c 100644
--- a/tests/baselines/reference/typeofOperatorWithStringType.errors.txt
+++ b/tests/baselines/reference/typeofOperatorWithStringType.errors.txt
@@ -1,14 +1,7 @@
 tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(44,1): error TS2695: Left side of comma operator is unused and has no side effects.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(50,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(51,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(52,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(54,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(55,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(56,1): error TS7028: Unused label.
-tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts(57,1): error TS7028: Unused label.
 
 
-==== tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts (8 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperatorWithStringType.ts (1 errors) ====
     // typeof  operator on string type
     var STRING: string;
     var STRING1: string[] = ["", "abc"];
@@ -61,24 +54,10 @@ tests/cases/conformance/expressions/unaryOperators/typeofOperator/typeofOperator
     var x: string[];
     var r: () => string;
     z: typeof STRING;
-    ~
-!!! error TS7028: Unused label.
     x: typeof STRING1;
-    ~
-!!! error TS7028: Unused label.
     r: typeof foo;
-    ~
-!!! error TS7028: Unused label.
     var y = { a: "", b: "" };
     z: typeof y.a;
-    ~
-!!! error TS7028: Unused label.
     z: typeof objA.a;
-    ~
-!!! error TS7028: Unused label.
     z: typeof A.foo;
-    ~
-!!! error TS7028: Unused label.
-    z: typeof M.n;
-    ~
-!!! error TS7028: Unused label.
\ No newline at end of file
+    z: typeof M.n;
\ No newline at end of file
diff --git a/tests/baselines/reference/undeclaredVarEmit.errors.txt b/tests/baselines/reference/undeclaredVarEmit.errors.txt
index bbf508ab005bc..ff5d2ef7e9eec 100644
--- a/tests/baselines/reference/undeclaredVarEmit.errors.txt
+++ b/tests/baselines/reference/undeclaredVarEmit.errors.txt
@@ -1,10 +1,7 @@
-tests/cases/compiler/undeclaredVarEmit.ts(1,1): error TS7028: Unused label.
 tests/cases/compiler/undeclaredVarEmit.ts(1,4): error TS2693: 'number' only refers to a type, but is being used as a value here.
 
 
-==== tests/cases/compiler/undeclaredVarEmit.ts (2 errors) ====
+==== tests/cases/compiler/undeclaredVarEmit.ts (1 errors) ====
     f: number;
-    ~
-!!! error TS7028: Unused label.
        ~~~~~~
 !!! error TS2693: 'number' only refers to a type, but is being used as a value here.
\ No newline at end of file
diff --git a/tests/baselines/reference/uniqueSymbols.types b/tests/baselines/reference/uniqueSymbols.types
index 55ce8d9c87ecb..3cae76bd7820b 100644
--- a/tests/baselines/reference/uniqueSymbols.types
+++ b/tests/baselines/reference/uniqueSymbols.types
@@ -699,19 +699,19 @@ g(N["s"]);
 
 // falsy expressions
 s || "";
->s || "" : unique symbol | ""
+>s || "" : "" | unique symbol
 >s : unique symbol
 >"" : ""
 
 N.s || "";
->N.s || "" : unique symbol | ""
+>N.s || "" : "" | unique symbol
 >N.s : unique symbol
 >N : typeof N
 >s : unique symbol
 >"" : ""
 
 N["s"] || "";
->N["s"] || "" : unique symbol | ""
+>N["s"] || "" : "" | unique symbol
 >N["s"] : unique symbol
 >N : typeof N
 >"s" : "s"
diff --git a/tests/baselines/reference/uniqueSymbolsDeclarations.types b/tests/baselines/reference/uniqueSymbolsDeclarations.types
index 6bfee5a040395..792a27f5182b5 100644
--- a/tests/baselines/reference/uniqueSymbolsDeclarations.types
+++ b/tests/baselines/reference/uniqueSymbolsDeclarations.types
@@ -699,19 +699,19 @@ g(N["s"]);
 
 // falsy expressions
 s || "";
->s || "" : unique symbol | ""
+>s || "" : "" | unique symbol
 >s : unique symbol
 >"" : ""
 
 N.s || "";
->N.s || "" : unique symbol | ""
+>N.s || "" : "" | unique symbol
 >N.s : unique symbol
 >N : typeof N
 >s : unique symbol
 >"" : ""
 
 N["s"] || "";
->N["s"] || "" : unique symbol | ""
+>N["s"] || "" : "" | unique symbol
 >N["s"] : unique symbol
 >N : typeof N
 >"s" : "s"
diff --git a/tests/baselines/reference/user/async.log b/tests/baselines/reference/user/async.log
index c78c122343c49..5c1efc71f027b 100644
--- a/tests/baselines/reference/user/async.log
+++ b/tests/baselines/reference/user/async.log
@@ -94,101 +94,101 @@ node_modules/async/dist/async.js(298,7): error TS2454: Variable 'unmasked' is us
 node_modules/async/dist/async.js(480,35): error TS2538: Type 'true' cannot be used as an index type.
 node_modules/async/dist/async.js(480,59): error TS2538: Type 'true' cannot be used as an index type.
 node_modules/async/dist/async.js(622,80): error TS2339: Property 'nodeType' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(745,84): error TS2339: Property 'nodeType' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(751,49): error TS2339: Property 'process' does not exist on type 'false | Global'.
+node_modules/async/dist/async.js(748,84): error TS2339: Property 'nodeType' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(754,49): error TS2339: Property 'process' does not exist on type 'false | Global'.
   Property 'process' does not exist on type 'false'.
-node_modules/async/dist/async.js(912,32): error TS2554: Expected 2 arguments, but got 1.
-node_modules/async/dist/async.js(1285,18): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1289,3): error TS2322: Type 'any[] | undefined' is not assignable to type 'any[]'.
+node_modules/async/dist/async.js(923,32): error TS2554: Expected 2 arguments, but got 1.
+node_modules/async/dist/async.js(1299,18): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1303,3): error TS2322: Type 'any[] | undefined' is not assignable to type 'any[]'.
   Type 'undefined' is not assignable to type 'any[]'.
-node_modules/async/dist/async.js(1495,9): error TS2322: Type 'null' is not assignable to type 'number | undefined'.
-node_modules/async/dist/async.js(1564,20): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(1566,51): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1608,17): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(1673,30): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1747,7): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1748,14): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1748,45): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1750,9): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1751,7): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1752,5): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1754,12): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1754,20): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1754,32): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1754,38): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1755,3): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1759,35): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(1937,10): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(1937,10): error TS8024: JSDoc '@param' tag has name '', but there is no parameter with that name.
-node_modules/async/dist/async.js(1976,16): error TS2554: Expected 3 arguments, but got 1.
-node_modules/async/dist/async.js(2102,20): error TS2345: Argument of type 'Function | undefined' is not assignable to parameter of type 'number | undefined'.
+node_modules/async/dist/async.js(1509,9): error TS2322: Type 'null' is not assignable to type 'number | undefined'.
+node_modules/async/dist/async.js(1578,20): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(1580,51): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1622,17): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(1687,30): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1761,7): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1762,14): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1762,45): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1764,9): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1765,7): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1766,5): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1768,12): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1768,20): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1768,32): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1768,38): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1769,3): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1773,35): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(1951,10): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(1951,10): error TS8024: JSDoc '@param' tag has name '', but there is no parameter with that name.
+node_modules/async/dist/async.js(1990,16): error TS2554: Expected 3 arguments, but got 1.
+node_modules/async/dist/async.js(2116,20): error TS2345: Argument of type 'Function | undefined' is not assignable to parameter of type 'number | undefined'.
   Type 'Function' is not assignable to type 'number | undefined'.
     Type 'Function' is not assignable to type 'number'.
-node_modules/async/dist/async.js(2260,21): error TS2554: Expected 0 arguments, but got 2.
-node_modules/async/dist/async.js(2411,20): error TS1005: '}' expected.
-node_modules/async/dist/async.js(2436,5): error TS2322: Type '{ [x: string]: any; _tasks: DLL; concurrency: any; payload: any; saturated: () => void; unsaturat...' is not assignable to type 'NodeModule'.
+node_modules/async/dist/async.js(2274,21): error TS2554: Expected 0 arguments, but got 2.
+node_modules/async/dist/async.js(2425,20): error TS1005: '}' expected.
+node_modules/async/dist/async.js(2450,5): error TS2322: Type '{ [x: string]: any; _tasks: DLL; concurrency: any; payload: any; saturated: () => void; unsaturat...' is not assignable to type 'NodeModule'.
   Property 'exports' is missing in type '{ [x: string]: any; _tasks: DLL; concurrency: any; payload: any; saturated: () => void; unsaturat...'.
-node_modules/async/dist/async.js(2507,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(2550,31): error TS2345: Argument of type 'IArguments' is not assignable to parameter of type 'any[] | undefined'.
+node_modules/async/dist/async.js(2521,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(2564,31): error TS2345: Argument of type 'IArguments' is not assignable to parameter of type 'any[] | undefined'.
   Type 'IArguments' is not assignable to type 'any[]'.
     Property 'flatMap' is missing in type 'IArguments'.
-node_modules/async/dist/async.js(2649,16): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(2668,31): error TS1005: ']' expected.
-node_modules/async/dist/async.js(2693,31): error TS1005: ']' expected.
-node_modules/async/dist/async.js(2710,28): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(2710,29): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(2710,30): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(2921,28): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(2921,29): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(2921,30): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(2963,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(2970,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(2971,28): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(3005,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(3008,9): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(3008,9): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
+node_modules/async/dist/async.js(2663,16): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(2682,31): error TS1005: ']' expected.
+node_modules/async/dist/async.js(2707,31): error TS1005: ']' expected.
+node_modules/async/dist/async.js(2724,28): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(2724,29): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(2724,30): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(2935,28): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(2935,29): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(2935,30): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(2977,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(2984,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(2985,28): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(3019,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(3022,9): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(3022,9): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
   Type 'undefined' is not assignable to type 'Function'.
-node_modules/async/dist/async.js(3081,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(3086,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(3087,28): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(3550,16): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(3626,28): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(3626,29): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(3626,30): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(3674,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(3813,14): error TS2339: Property 'memo' does not exist on type '(...args: any[]) => void'.
-node_modules/async/dist/async.js(3814,14): error TS2339: Property 'unmemoized' does not exist on type '(...args: any[]) => void'.
-node_modules/async/dist/async.js(3834,23): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(3834,24): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(3834,25): error TS1003: Identifier expected.
-node_modules/async/dist/async.js(4045,20): error TS1005: '}' expected.
-node_modules/async/dist/async.js(4081,5): error TS2322: Type '{ [x: string]: any; _tasks: DLL; concurrency: any; payload: any; saturated: () => void; unsaturat...' is not assignable to type 'NodeModule'.
-node_modules/async/dist/async.js(4103,20): error TS1005: '}' expected.
-node_modules/async/dist/async.js(4114,7): error TS2339: Property 'push' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4119,11): error TS2339: Property 'started' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4126,19): error TS2339: Property 'drain' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4131,26): error TS2339: Property '_tasks' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4144,19): error TS2339: Property '_tasks' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4146,19): error TS2339: Property '_tasks' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4149,26): error TS2339: Property 'process' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4153,14): error TS2339: Property 'unshift' does not exist on type 'NodeModule'.
-node_modules/async/dist/async.js(4367,5): error TS2322: Type 'any[] | {}' is not assignable to type 'any[]'.
+node_modules/async/dist/async.js(3095,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(3100,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(3101,28): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(3564,16): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(3640,28): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(3640,29): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(3640,30): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(3688,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(3827,14): error TS2339: Property 'memo' does not exist on type '(...args: any[]) => void'.
+node_modules/async/dist/async.js(3828,14): error TS2339: Property 'unmemoized' does not exist on type '(...args: any[]) => void'.
+node_modules/async/dist/async.js(3848,23): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(3848,24): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(3848,25): error TS1003: Identifier expected.
+node_modules/async/dist/async.js(4059,20): error TS1005: '}' expected.
+node_modules/async/dist/async.js(4095,5): error TS2322: Type '{ [x: string]: any; _tasks: DLL; concurrency: any; payload: any; saturated: () => void; unsaturat...' is not assignable to type 'NodeModule'.
+node_modules/async/dist/async.js(4117,20): error TS1005: '}' expected.
+node_modules/async/dist/async.js(4128,7): error TS2339: Property 'push' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4133,11): error TS2339: Property 'started' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4140,19): error TS2339: Property 'drain' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4145,26): error TS2339: Property '_tasks' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4158,19): error TS2339: Property '_tasks' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4160,19): error TS2339: Property '_tasks' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4163,26): error TS2339: Property 'process' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4167,14): error TS2339: Property 'unshift' does not exist on type 'NodeModule'.
+node_modules/async/dist/async.js(4381,5): error TS2322: Type 'any[] | {}' is not assignable to type 'any[]'.
   Type '{}' is not assignable to type 'any[]'.
     Property 'flatMap' is missing in type '{}'.
-node_modules/async/dist/async.js(4603,17): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(4603,17): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
+node_modules/async/dist/async.js(4617,17): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(4617,17): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
   Type 'undefined' is not assignable to type 'Function'.
-node_modules/async/dist/async.js(4917,19): error TS2339: Property 'code' does not exist on type 'Error'.
-node_modules/async/dist/async.js(4919,23): error TS2339: Property 'info' does not exist on type 'Error'.
-node_modules/async/dist/async.js(5090,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(5146,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(5165,20): error TS2339: Property 'unmemoized' does not exist on type 'Function'.
-node_modules/async/dist/async.js(5208,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
-node_modules/async/dist/async.js(5211,9): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(5211,9): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
+node_modules/async/dist/async.js(4931,19): error TS2339: Property 'code' does not exist on type 'Error'.
+node_modules/async/dist/async.js(4933,23): error TS2339: Property 'info' does not exist on type 'Error'.
+node_modules/async/dist/async.js(5104,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(5160,9): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(5179,20): error TS2339: Property 'unmemoized' does not exist on type 'Function'.
+node_modules/async/dist/async.js(5222,25): error TS2722: Cannot invoke an object which is possibly 'undefined'.
+node_modules/async/dist/async.js(5225,9): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(5225,9): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
   Type 'undefined' is not assignable to type 'Function'.
-node_modules/async/dist/async.js(5315,20): error TS2532: Object is possibly 'undefined'.
-node_modules/async/dist/async.js(5315,20): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
+node_modules/async/dist/async.js(5329,20): error TS2532: Object is possibly 'undefined'.
+node_modules/async/dist/async.js(5329,20): error TS2684: The 'this' context of type 'Function | undefined' is not assignable to method's 'this' of type 'Function'.
   Type 'undefined' is not assignable to type 'Function'.
 node_modules/async/doDuring.js(37,12): error TS2304: Cannot find name 'AsyncFunction'.
 node_modules/async/doDuring.js(39,12): error TS2304: Cannot find name 'AsyncFunction'.
@@ -519,7 +519,7 @@ node_modules/async/internal/doParallelLimit.js(20,20): error TS2695: Left side o
 node_modules/async/internal/doParallelLimit.js(20,60): error TS2695: Left side of comma operator is unused and has no side effects.
 node_modules/async/internal/eachOfLimit.js(32,21): error TS2695: Left side of comma operator is unused and has no side effects.
 node_modules/async/internal/eachOfLimit.js(36,25): error TS2695: Left side of comma operator is unused and has no side effects.
-node_modules/async/internal/eachOfLimit.js(64,49): error TS2695: Left side of comma operator is unused and has no side effects.
+node_modules/async/internal/eachOfLimit.js(66,49): error TS2695: Left side of comma operator is unused and has no side effects.
 node_modules/async/internal/filter.js(64,29): error TS2695: Left side of comma operator is unused and has no side effects.
 node_modules/async/internal/filter.js(66,18): error TS2695: Left side of comma operator is unused and has no side effects.
 node_modules/async/internal/filter.js(72,19): error TS2695: Left side of comma operator is unused and has no side effects.
diff --git a/tests/baselines/reference/user/follow-redirects.log b/tests/baselines/reference/user/follow-redirects.log
index d169f8a97c9c8..625b739fd43c6 100644
--- a/tests/baselines/reference/user/follow-redirects.log
+++ b/tests/baselines/reference/user/follow-redirects.log
@@ -1,11 +1,11 @@
 Exit Code: 1
 Standard output:
-node_modules/follow-redirects/index.js(66,10): error TS2339: Property 'emit' does not exist on type 'RedirectableRequest'.
-node_modules/follow-redirects/index.js(67,10): error TS2339: Property 'abort' does not exist on type 'RedirectableRequest'.
-node_modules/follow-redirects/index.js(171,12): error TS2339: Property 'emit' does not exist on type 'RedirectableRequest'.
-node_modules/follow-redirects/index.js(205,35): error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
+node_modules/follow-redirects/index.js(70,10): error TS2339: Property 'emit' does not exist on type 'RedirectableRequest'.
+node_modules/follow-redirects/index.js(71,10): error TS2339: Property 'abort' does not exist on type 'RedirectableRequest'.
+node_modules/follow-redirects/index.js(184,12): error TS2339: Property 'emit' does not exist on type 'RedirectableRequest'.
+node_modules/follow-redirects/index.js(218,35): error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
   Type 'undefined' is not assignable to type 'string'.
-node_modules/follow-redirects/index.js(214,10): error TS2339: Property 'emit' does not exist on type 'RedirectableRequest'.
+node_modules/follow-redirects/index.js(228,10): error TS2339: Property 'emit' does not exist on type 'RedirectableRequest'.
 
 
 
diff --git a/tests/baselines/reference/user/puppeteer.log b/tests/baselines/reference/user/puppeteer.log
index 86623a0aafc9a..f05a564517cd8 100644
--- a/tests/baselines/reference/user/puppeteer.log
+++ b/tests/baselines/reference/user/puppeteer.log
@@ -62,7 +62,7 @@ lib/externs.d.ts(17,121): error TS2503: Cannot find namespace 'Protocol'.
 lib/helper.js(59,15): error TS2503: Cannot find namespace 'Protocol'.
 lib/helper.js(77,15): error TS2503: Cannot find namespace 'Protocol'.
 lib/helper.js(101,15): error TS2503: Cannot find namespace 'Protocol'.
-node_modules/@types/node/index.d.ts(911,22): error TS2300: Duplicate identifier 'EventEmitter'.
+node_modules/@types/node/index.d.ts(912,22): error TS2300: Duplicate identifier 'EventEmitter'.
 
 
 
diff --git a/tests/baselines/reference/user/uglify-js.log b/tests/baselines/reference/user/uglify-js.log
index 6857fedda3f8e..8d4125a3a4761 100644
--- a/tests/baselines/reference/user/uglify-js.log
+++ b/tests/baselines/reference/user/uglify-js.log
@@ -14,58 +14,58 @@ node_modules/uglify-js/lib/compress.js(1195,112): error TS2532: Object is possib
 node_modules/uglify-js/lib/compress.js(1196,29): error TS2532: Object is possibly 'undefined'.
 node_modules/uglify-js/lib/compress.js(1205,87): error TS2322: Type 'false' is not assignable to type 'number'.
 node_modules/uglify-js/lib/compress.js(1213,29): error TS2322: Type 'false' is not assignable to type 'never'.
-node_modules/uglify-js/lib/compress.js(1311,38): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(1404,38): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
-node_modules/uglify-js/lib/compress.js(1501,27): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(1533,26): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(1947,44): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(2139,19): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(2399,27): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(3139,23): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(3152,33): error TS2322: Type '"f"' is not assignable to type 'boolean'.
-node_modules/uglify-js/lib/compress.js(3289,18): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(3299,33): error TS2339: Property 'add' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3303,32): error TS2339: Property 'add' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3309,40): error TS2339: Property 'add' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3318,41): error TS2339: Property 'add' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3335,14): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(3337,40): error TS2339: Property 'get' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3345,33): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
-node_modules/uglify-js/lib/compress.js(3419,63): error TS2339: Property 'get' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3608,23): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(3625,36): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
-node_modules/uglify-js/lib/compress.js(3631,38): error TS2339: Property 'set' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3635,40): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
-node_modules/uglify-js/lib/compress.js(3660,22): error TS2339: Property 'each' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3665,30): error TS2339: Property 'del' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3670,30): error TS2339: Property 'set' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3681,41): error TS2339: Property 'has' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3683,48): error TS2339: Property 'get' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3695,41): error TS2339: Property 'has' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3697,48): error TS2339: Property 'get' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3803,21): error TS2403: Subsequent variable declarations must have the same type.  Variable 'defs' must be of type 'Dictionary', but here has type 'any'.
-node_modules/uglify-js/lib/compress.js(3805,36): error TS2339: Property 'get' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3834,22): error TS2339: Property 'set' does not exist on type 'Dictionary'.
-node_modules/uglify-js/lib/compress.js(3854,17): error TS2447: The '|=' operator is not allowed for boolean types. Consider using '||' instead.
-node_modules/uglify-js/lib/compress.js(3879,30): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(4017,18): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(4316,17): error TS2403: Subsequent variable declarations must have the same type.  Variable 'body' must be of type 'any[]', but here has type 'any'.
-node_modules/uglify-js/lib/compress.js(4400,22): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(4748,30): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(4755,25): error TS2403: Subsequent variable declarations must have the same type.  Variable 'code' must be of type 'string', but here has type '{ [x: string]: any; get: () => string; toString: () => string; indent: () => void; indentation: (...'.
-node_modules/uglify-js/lib/compress.js(4759,36): error TS2532: Object is possibly 'undefined'.
-node_modules/uglify-js/lib/compress.js(4764,41): error TS2339: Property 'get' does not exist on type 'string'.
-node_modules/uglify-js/lib/compress.js(5251,18): error TS2454: Variable 'is_strict_comparison' is used before being assigned.
-node_modules/uglify-js/lib/compress.js(5690,25): error TS2365: Operator '==' cannot be applied to types 'boolean' and '"f"'.
-node_modules/uglify-js/lib/compress.js(5717,32): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(5777,24): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(5849,24): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(5855,26): error TS2554: Expected 0 arguments, but got 1.
-node_modules/uglify-js/lib/compress.js(6205,43): error TS2454: Variable 'property' is used before being assigned.
-node_modules/uglify-js/lib/compress.js(6219,25): error TS2403: Subsequent variable declarations must have the same type.  Variable 'value' must be of type 'number', but here has type 'any'.
-node_modules/uglify-js/lib/compress.js(6222,46): error TS2339: Property 'has_side_effects' does not exist on type 'number'.
-node_modules/uglify-js/lib/compress.js(6229,25): error TS2403: Subsequent variable declarations must have the same type.  Variable 'value' must be of type 'number', but here has type 'any'.
-node_modules/uglify-js/lib/compress.js(6282,19): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(1313,38): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(1406,38): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
+node_modules/uglify-js/lib/compress.js(1503,27): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(1535,26): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(1949,44): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(2141,19): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(2401,27): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(3141,23): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(3154,33): error TS2322: Type '"f"' is not assignable to type 'boolean'.
+node_modules/uglify-js/lib/compress.js(3291,18): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(3301,33): error TS2339: Property 'add' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3305,32): error TS2339: Property 'add' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3311,40): error TS2339: Property 'add' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3320,41): error TS2339: Property 'add' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3337,14): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(3339,40): error TS2339: Property 'get' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3347,33): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
+node_modules/uglify-js/lib/compress.js(3421,63): error TS2339: Property 'get' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3610,23): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(3627,36): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
+node_modules/uglify-js/lib/compress.js(3633,38): error TS2339: Property 'set' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3637,40): error TS2339: Property 'parent' does not exist on type 'TreeTransformer'.
+node_modules/uglify-js/lib/compress.js(3662,22): error TS2339: Property 'each' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3667,30): error TS2339: Property 'del' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3672,30): error TS2339: Property 'set' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3683,41): error TS2339: Property 'has' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3685,48): error TS2339: Property 'get' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3697,41): error TS2339: Property 'has' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3699,48): error TS2339: Property 'get' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3805,21): error TS2403: Subsequent variable declarations must have the same type.  Variable 'defs' must be of type 'Dictionary', but here has type 'any'.
+node_modules/uglify-js/lib/compress.js(3807,36): error TS2339: Property 'get' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3836,22): error TS2339: Property 'set' does not exist on type 'Dictionary'.
+node_modules/uglify-js/lib/compress.js(3856,17): error TS2447: The '|=' operator is not allowed for boolean types. Consider using '||' instead.
+node_modules/uglify-js/lib/compress.js(3881,30): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(4019,18): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(4318,17): error TS2403: Subsequent variable declarations must have the same type.  Variable 'body' must be of type 'any[]', but here has type 'any'.
+node_modules/uglify-js/lib/compress.js(4402,22): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(4750,30): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(4757,25): error TS2403: Subsequent variable declarations must have the same type.  Variable 'code' must be of type 'string', but here has type '{ [x: string]: any; get: () => string; toString: () => string; indent: () => void; indentation: (...'.
+node_modules/uglify-js/lib/compress.js(4761,36): error TS2532: Object is possibly 'undefined'.
+node_modules/uglify-js/lib/compress.js(4766,41): error TS2339: Property 'get' does not exist on type 'string'.
+node_modules/uglify-js/lib/compress.js(5253,18): error TS2454: Variable 'is_strict_comparison' is used before being assigned.
+node_modules/uglify-js/lib/compress.js(5692,25): error TS2365: Operator '==' cannot be applied to types 'boolean' and '"f"'.
+node_modules/uglify-js/lib/compress.js(5719,32): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(5779,24): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(5851,24): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(5857,26): error TS2554: Expected 0 arguments, but got 1.
+node_modules/uglify-js/lib/compress.js(6207,43): error TS2454: Variable 'property' is used before being assigned.
+node_modules/uglify-js/lib/compress.js(6221,25): error TS2403: Subsequent variable declarations must have the same type.  Variable 'value' must be of type 'number', but here has type 'any'.
+node_modules/uglify-js/lib/compress.js(6224,46): error TS2339: Property 'has_side_effects' does not exist on type 'number'.
+node_modules/uglify-js/lib/compress.js(6231,25): error TS2403: Subsequent variable declarations must have the same type.  Variable 'value' must be of type 'number', but here has type 'any'.
+node_modules/uglify-js/lib/compress.js(6284,19): error TS2554: Expected 0 arguments, but got 1.
 node_modules/uglify-js/lib/minify.js(166,75): error TS2339: Property 'compress' does not exist on type 'Compressor'.
 node_modules/uglify-js/lib/mozilla-ast.js(569,18): error TS2554: Expected 0 arguments, but got 1.
 node_modules/uglify-js/lib/output.js(481,22): error TS2554: Expected 0 arguments, but got 1.
diff --git a/tests/baselines/reference/validMultipleVariableDeclarations.errors.txt b/tests/baselines/reference/validMultipleVariableDeclarations.errors.txt
deleted file mode 100644
index 8f751e9efeead..0000000000000
--- a/tests/baselines/reference/validMultipleVariableDeclarations.errors.txt
+++ /dev/null
@@ -1,45 +0,0 @@
-tests/cases/conformance/statements/VariableStatements/validMultipleVariableDeclarations.ts(9,1): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/conformance/statements/VariableStatements/validMultipleVariableDeclarations.ts (1 errors) ====
-    // all expected to be valid
-    
-    var x: number;
-    var x = 2;
-    if (true) {
-        var x = 3;
-        for (var x = 0; ;) { }
-    }
-    var x = <number>undefined;
-    ~~~
-!!! error TS7027: Unreachable code detected.
-    
-    // new declaration space, making redeclaring x as a string valid
-    function declSpace() {
-        var x = 'this is a string';
-    }
-    
-    interface Point { x: number; y: number; }
-    
-    var p: Point;
-    var p = { x: 1, y: 2 };
-    var p: Point = { x: 0, y: undefined };
-    var p = { x: 1, y: <number>undefined };
-    var p: { x: number; y: number; } = { x: 1, y: 2 };
-    var p = <{ x: number; y: number; }>{ x: 0, y: undefined };
-    var p: typeof p;
-    
-    var fn = function (s: string) { return 42; }
-    var fn = (s: string) => 3;
-    var fn: (s: string) => number;
-    var fn: { (s: string): number };
-    var fn = <(s: string) => number> null;
-    var fn: typeof fn;
-    
-    var a: string[]; 
-    var a = ['a', 'b']
-    var a = <string[]>[];
-    var a: string[] = [];
-    var a = new Array<string>();
-    var a: typeof a;
-    
\ No newline at end of file
diff --git a/tests/baselines/reference/whileContinueStatements.errors.txt b/tests/baselines/reference/whileContinueStatements.errors.txt
deleted file mode 100644
index c2009b02600ec..0000000000000
--- a/tests/baselines/reference/whileContinueStatements.errors.txt
+++ /dev/null
@@ -1,59 +0,0 @@
-tests/cases/conformance/statements/continueStatements/whileContinueStatements.ts(5,1): error TS7027: Unreachable code detected.
-
-
-==== tests/cases/conformance/statements/continueStatements/whileContinueStatements.ts (1 errors) ====
-    while(true) {
-        continue;
-    } 
-    
-    while (true) {
-    ~~~~~
-!!! error TS7027: Unreachable code detected.
-        if (true) {
-            continue;
-        }
-    }
-    
-    ONE:
-    
-    while (true) {
-        continue ONE;
-    }
-    
-    TWO:
-    THREE:
-    while (true) {
-        continue THREE;
-    }
-    
-    FOUR:
-    while (true) {
-        FIVE:
-        while (true) {
-            continue FOUR;
-        }
-    }
-    
-    while (true) {
-        SIX:
-        while (true)
-            continue SIX;
-    }
-    
-    SEVEN:
-    while (true)
-        while (true)
-            while (true)
-                continue SEVEN;
-    
-    EIGHT:
-    while (true) {
-        var fn = function () { }
-        continue EIGHT;
-    }
-    
-    NINE:
-    while (true) {
-        if (true) { continue NINE; }
-    }
-    
\ No newline at end of file
diff --git a/tests/cases/compiler/cf.ts b/tests/cases/compiler/cf.ts
index a37f626cd898a..4b1afcbf00036 100644
--- a/tests/cases/compiler/cf.ts
+++ b/tests/cases/compiler/cf.ts
@@ -1,3 +1,4 @@
+// @allowUnreachableCode: false
 function f() {
     var z;
     var x=10;
@@ -38,7 +39,7 @@ function f() {
     }
     catch (e) {
         x++;
-    }    
+    }
     finally {
         x+=3;
     }
diff --git a/tests/cases/compiler/commaOperator1.ts b/tests/cases/compiler/commaOperator1.ts
index 0cba7f1cd53f6..2a51e06eadce0 100644
--- a/tests/cases/compiler/commaOperator1.ts
+++ b/tests/cases/compiler/commaOperator1.ts
@@ -1,3 +1,4 @@
+// @allowUnreachableCode: false
 var v1 = ((1, 2, 3), 4, 5, (6, 7));
 function f1() {
     var a = 1;
diff --git a/tests/cases/compiler/commaOperatorLeftSideUnused.ts b/tests/cases/compiler/commaOperatorLeftSideUnused.ts
index b4ac6ac1a178b..e5bab897afa76 100644
--- a/tests/cases/compiler/commaOperatorLeftSideUnused.ts
+++ b/tests/cases/compiler/commaOperatorLeftSideUnused.ts
@@ -1,3 +1,4 @@
+// @allowUnreachableCode: false
 var xx: any;
 var yy: any;
 
diff --git a/tests/cases/compiler/evalAfter0.ts b/tests/cases/compiler/evalAfter0.ts
index 2245150ce6ab3..8b9ac51d5d473 100644
--- a/tests/cases/compiler/evalAfter0.ts
+++ b/tests/cases/compiler/evalAfter0.ts
@@ -1,3 +1,4 @@
+// @allowUnreachableCode: false
 (0,eval)("10"); // fine: special case for eval
 
 declare var eva;
diff --git a/tests/cases/compiler/jsFileCompilationBindErrors.ts b/tests/cases/compiler/jsFileCompilationBindErrors.ts
index 7c43b329a4740..dc34a38afffe8 100644
--- a/tests/cases/compiler/jsFileCompilationBindErrors.ts
+++ b/tests/cases/compiler/jsFileCompilationBindErrors.ts
@@ -1,6 +1,8 @@
 // @allowJs: true
 // @checkJs: true
 // @noEmit: true
+// @allowUnreachableCode: false
+
 // @filename: a.js
 let C = "sss";
 let C = 0;  // Error: Cannot redeclare block-scoped variable 'C'.
diff --git a/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts b/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts
index e92732313163a..29dfd68bb0411 100644
--- a/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts
+++ b/tests/cases/compiler/jsFileCompilationBindReachabilityErrors.ts
@@ -1,8 +1,11 @@
 // @allowJs: true
 // @checkJs: true
 // @noEmit: true
-// @filename: a.js
 // @noFallthroughCasesInSwitch: true
+// @allowUnreachableCode: false
+// @allowUnusedLabels: false
+
+// @filename: a.js
 function foo(a, b) {
     switch (a) {
         case 10:
diff --git a/tests/cases/compiler/unreachableJavascriptChecked.ts b/tests/cases/compiler/unreachableJavascriptChecked.ts
index 4db98c4c8c4e1..afddcba6a23b1 100644
--- a/tests/cases/compiler/unreachableJavascriptChecked.ts
+++ b/tests/cases/compiler/unreachableJavascriptChecked.ts
@@ -2,6 +2,7 @@
 // @allowJs: true
 // @checkJs: true
 // @outDir: out
+// @allowUnreachableCode: false
 function unreachable() {
     return 1;
     return 2;
diff --git a/tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts b/tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts
index 176c2043344a4..2964561dc6302 100644
--- a/tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts
+++ b/tests/cases/conformance/es7/exponentiationOperator/compoundExponentiationAssignmentLHSIsValue.ts
@@ -1,3 +1,4 @@
+// @allowUnreachableCode: false
 // expected error for all the LHS of compound assignments (arithmetic and addition)
 var value: any;
 
diff --git a/tests/cases/conformance/expressions/commaOperator/commaOperatorWithoutOperand.ts b/tests/cases/conformance/expressions/commaOperator/commaOperatorWithoutOperand.ts
index e52e6e30bfa72..dce2222c967c4 100644
--- a/tests/cases/conformance/expressions/commaOperator/commaOperatorWithoutOperand.ts
+++ b/tests/cases/conformance/expressions/commaOperator/commaOperatorWithoutOperand.ts
@@ -1,3 +1,4 @@
+// @allowUnreachableCode: false
 var ANY: any;
 var BOOLEAN: boolean;
 var NUMBER: number;
diff --git a/tests/cases/conformance/types/literal/literalTypeWidening.ts b/tests/cases/conformance/types/literal/literalTypeWidening.ts
index 98ed328f0d27d..4c818793142b1 100644
--- a/tests/cases/conformance/types/literal/literalTypeWidening.ts
+++ b/tests/cases/conformance/types/literal/literalTypeWidening.ts
@@ -59,6 +59,18 @@ function f5() {
     let v4 = c4;
 }
 
+declare function widening<T>(x: T): T;
+declare function nonWidening<T extends string | number | symbol>(x: T): T;
+
+function f6(cond: boolean) {
+    let x1 = widening('a');
+    let x2 = widening(10);
+    let x3 = widening(cond ? 'a' : 10);
+    let y1 = nonWidening('a');
+    let y2 = nonWidening(10);
+    let y3 = nonWidening(cond ? 'a' : 10);
+}
+
 // Repro from #10898
 
 type FAILURE = "FAILURE";
@@ -94,4 +106,24 @@ type TestEvent = "onmouseover" | "onmouseout";
 
 function onMouseOver(): TestEvent { return "onmouseover"; }
 
-let x = onMouseOver();
\ No newline at end of file
+let x = onMouseOver();
+
+// Repro from #23649
+
+export function Set<K extends string>(...keys: K[]): Record<K, true | undefined> {
+  const result = {} as Record<K, true | undefined>
+  keys.forEach(key => result[key] = true)
+  return result
+}
+
+export function keys<K extends string, V>(obj: Record<K, V>): K[] {
+  return Object.keys(obj) as K[]
+}
+
+type Obj = { code: LangCode }
+
+const langCodeSet = Set('fr', 'en', 'es', 'it', 'nl')
+export type LangCode = keyof typeof langCodeSet
+export const langCodes = keys(langCodeSet)
+
+const arr: Obj[] = langCodes.map(code => ({ code }))
diff --git a/tests/cases/fourslash/codeFixUnreachableCode.ts b/tests/cases/fourslash/codeFixUnreachableCode.ts
index bbe716e792e35..5f70d51c1ee10 100644
--- a/tests/cases/fourslash/codeFixUnreachableCode.ts
+++ b/tests/cases/fourslash/codeFixUnreachableCode.ts
@@ -2,7 +2,7 @@
 
 ////function f() {
 ////    return f();
-////    return 1;
+////    [|return|] 1;
 ////    function f() {}
 ////    return 2;
 ////    type T = number;
@@ -10,11 +10,18 @@
 ////    const enum E {}
 ////    enum E {}
 ////    namespace N { export type T = number; }
-////    namespace N { export const x = 0; }
-////    var x;
-////    var y = 0;
+////    namespace N { export const x: T = 0; }
+////    var x: I;
+////    var y: T = 0;
+////    E; N; x; y;
 ////}
 
+verify.getSuggestionDiagnostics([{
+    message: "Unreachable code detected.",
+    code: 7027,
+    reportsUnnecessary: true,
+}]);
+
 verify.codeFix({
     description: "Remove unreachable code",
     index: 0,
@@ -26,6 +33,6 @@ verify.codeFix({
     interface I {}
     const enum E {}
     namespace N { export type T = number; }
-    var x;
+    var x: I;
 }`,
 });
diff --git a/tests/cases/fourslash/codeFixUnreachableCode_noSuggestionIfDisabled.ts b/tests/cases/fourslash/codeFixUnreachableCode_noSuggestionIfDisabled.ts
new file mode 100644
index 0000000000000..35ad3c430a335
--- /dev/null
+++ b/tests/cases/fourslash/codeFixUnreachableCode_noSuggestionIfDisabled.ts
@@ -0,0 +1,7 @@
+/// <reference path='fourslash.ts' />
+
+// @allowUnreachableCode: true
+
+////if (false) 0;
+
+verify.getSuggestionDiagnostics([]);
diff --git a/tests/cases/fourslash/codeFixUnusedIdentifier_suggestion.ts b/tests/cases/fourslash/codeFixUnusedIdentifier_suggestion.ts
index de671de1e5db8..b830ccad74640 100644
--- a/tests/cases/fourslash/codeFixUnusedIdentifier_suggestion.ts
+++ b/tests/cases/fourslash/codeFixUnusedIdentifier_suggestion.ts
@@ -10,13 +10,13 @@ verify.getSuggestionDiagnostics([
         message: "'p' is declared but its value is never read.",
         range: r0,
         code: 6133,
-        unused: true,
+        reportsUnnecessary: true,
     },
     {
         message: "'x' is declared but its value is never read.",
         range: r1,
         code: 6133,
-        unused: true,
+        reportsUnnecessary: true,
     }
 ]);
 
diff --git a/tests/cases/fourslash/codeFixUnusedLabel.ts b/tests/cases/fourslash/codeFixUnusedLabel.ts
index 0feea173b0c2b..38265aa818e10 100644
--- a/tests/cases/fourslash/codeFixUnusedLabel.ts
+++ b/tests/cases/fourslash/codeFixUnusedLabel.ts
@@ -1,8 +1,12 @@
 /// <reference path='fourslash.ts' />
 
-// @noUnusedLocals: true
+/////* a */[|label|]/* b */:/* c */while (1) {}
 
-/////* a */label/* b */:/* c */while (1) {}
+verify.getSuggestionDiagnostics([{
+    message: "Unused label.",
+    code: 7028,
+    reportsUnnecessary: true,
+}]);
 
 verify.codeFix({
     description: "Remove unused label",
diff --git a/tests/cases/fourslash/codeFixUnusedLabel_noSuggestionIfDisabled.ts b/tests/cases/fourslash/codeFixUnusedLabel_noSuggestionIfDisabled.ts
new file mode 100644
index 0000000000000..a7e504d2f66dd
--- /dev/null
+++ b/tests/cases/fourslash/codeFixUnusedLabel_noSuggestionIfDisabled.ts
@@ -0,0 +1,7 @@
+/// <reference path='fourslash.ts' />
+
+// @allowUnusedLabels: true
+
+////foo: while (true) {}
+
+verify.getSuggestionDiagnostics([]);
diff --git a/tests/cases/fourslash/formatLiteralTypeInUnionOrIntersectionType.ts b/tests/cases/fourslash/formatLiteralTypeInUnionOrIntersectionType.ts
new file mode 100644
index 0000000000000..81bba56adf20f
--- /dev/null
+++ b/tests/cases/fourslash/formatLiteralTypeInUnionOrIntersectionType.ts
@@ -0,0 +1,37 @@
+/// <reference path='fourslash.ts' />
+
+//// type NumberAndString = {
+////     a: number
+//// } & {
+////     b: string
+//// };
+//// 
+//// type NumberOrString = {
+////     a: number
+//// } | {
+////     b: string
+//// };
+//// 
+//// type Complexed =
+////     Foo &
+////     Bar |
+////     Baz;
+
+
+format.document();
+verify.currentFileContentIs(`type NumberAndString = {
+    a: number
+} & {
+    b: string
+};
+
+type NumberOrString = {
+    a: number
+} | {
+    b: string
+};
+
+type Complexed =
+    Foo &
+    Bar |
+    Baz;`);
diff --git a/tests/cases/fourslash/fourslash.ts b/tests/cases/fourslash/fourslash.ts
index b8b06edca15a6..57eda1e09471e 100644
--- a/tests/cases/fourslash/fourslash.ts
+++ b/tests/cases/fourslash/fourslash.ts
@@ -516,7 +516,7 @@ declare namespace FourSlashInterface {
         /** @default `test.ranges()[0]` */
         range?: Range;
         code: number;
-        unused?: true;
+        reportsUnnecessary?: true;
     }
     interface VerifyDocumentHighlightsOptions {
         filesToSearch?: ReadonlyArray<string>;
diff --git a/tests/cases/fourslash/suggestionOfUnusedVariableWithExternalModule.ts b/tests/cases/fourslash/suggestionOfUnusedVariableWithExternalModule.ts
index b86f79a8e4914..77d0b6157fde5 100644
--- a/tests/cases/fourslash/suggestionOfUnusedVariableWithExternalModule.ts
+++ b/tests/cases/fourslash/suggestionOfUnusedVariableWithExternalModule.ts
@@ -3,15 +3,15 @@
 //@allowJs: true
 
 // @Filename: /mymodule.js
-////(function ([|root|], factory) {
-////    module.exports = factory();
-////}(this, function () {
-////    var [|unusedVar|] = "something";
-////    return {};
+////(function ([|root|], factory) {
+////    module.exports = factory();
+////}(this, function () {
+////    var [|unusedVar|] = "something";
+////    return {};
 ////}));
 
 // @Filename: /app.js
-//////@ts-check
+//////@ts-check
 ////require("./mymodule");
 
 const [range0, range1] = test.ranges();
@@ -20,12 +20,17 @@ goTo.file("/app.js");
 verify.getSuggestionDiagnostics([]);
 
 goTo.file("/mymodule.js");
-verify.getSuggestionDiagnostics([{
-    message: "'root' is declared but its value is never read.",
-    code: 6133,
-    range: range0
-}, {
+verify.getSuggestionDiagnostics([
+    {
+        message: "'root' is declared but its value is never read.",
+        code: 6133,
+        range: range0,
+        reportsUnnecessary: true,
+    },
+    {
         message: "'unusedVar' is declared but its value is never read.",
         code: 6133,
-        range: range1
-}]);
+        range: range1,
+        reportsUnnecessary: true,
+    },
+]);