Fix completion and quick info crash in type parameter in function in type alias

src/services/services.ts

@@ -1901,7 +1901,7 @@ namespace ts {
                     sourceMapText = text;
                 }
                 else {
-                    Debug.assert(outputText === undefined, "Unexpected multiple outputs for the file: " + name);
+                    Debug.assert(outputText === undefined, `Unexpected multiple outputs for the file: '${name}'`);
                     outputText = text;
                 }
             },
@@ -4248,28 +4248,31 @@ namespace ts {
                 }
                 else {
                     // Method/function type parameter
-                    let container = getContainingFunction(location);
-                    if (container) {
-                        let signatureDeclaration = <SignatureDeclaration>getDeclarationOfKind(symbol, SyntaxKind.TypeParameter).parent;
-                        let signature = typeChecker.getSignatureFromDeclaration(signatureDeclaration);
-                        if (signatureDeclaration.kind === SyntaxKind.ConstructSignature) {
-                            displayParts.push(keywordPart(SyntaxKind.NewKeyword));
-                            displayParts.push(spacePart());
+                    let declaration = <Node>getDeclarationOfKind(symbol, SyntaxKind.TypeParameter);
+                    Debug.assert(declaration !== undefined);
+                    declaration = declaration.parent;
+
+                    if (declaration) {
+                        if (isFunctionLikeKind(declaration.kind)) {
+                            const signature = typeChecker.getSignatureFromDeclaration(<SignatureDeclaration>declaration);
+                            if (declaration.kind === SyntaxKind.ConstructSignature) {
+                                displayParts.push(keywordPart(SyntaxKind.NewKeyword));
+                                displayParts.push(spacePart());
+                            }
+                            else if (declaration.kind !== SyntaxKind.CallSignature && (<SignatureDeclaration>declaration).name) {
+                                addFullSymbolName(declaration.symbol);
+                            }
+                            addRange(displayParts, signatureToDisplayParts(typeChecker, signature, sourceFile, TypeFormatFlags.WriteTypeArgumentsOfSignature));
                         }
-                        else if (signatureDeclaration.kind !== SyntaxKind.CallSignature && signatureDeclaration.name) {
-                            addFullSymbolName(signatureDeclaration.symbol);
+                        else {
+                            // Type alias type parameter
+                            // For example
+                            //      type list<T> = T[];  // Both T will go through same code path
+                            displayParts.push(keywordPart(SyntaxKind.TypeKeyword));
+                            displayParts.push(spacePart());
+                            addFullSymbolName(declaration.symbol);
+                            writeTypeParametersOfSymbol(declaration.symbol, sourceFile);
                         }
-                        addRange(displayParts, signatureToDisplayParts(typeChecker, signature, sourceFile, TypeFormatFlags.WriteTypeArgumentsOfSignature));
-                    }
-                    else {
-                        // Type  aliash type parameter
-                        // For example
-                        //      type list<T> = T[];  // Both T will go through same code path
-                        let declaration = <TypeAliasDeclaration>getDeclarationOfKind(symbol, SyntaxKind.TypeParameter).parent;
-                        displayParts.push(keywordPart(SyntaxKind.TypeKeyword));
-                        displayParts.push(spacePart());
-                        addFullSymbolName(declaration.symbol);
-                        writeTypeParametersOfSymbol(declaration.symbol, sourceFile);
                     }
                 }
             }

tests/cases/fourslash/completionListInTypeParameterOfTypeAlias3.ts

@@ -0,0 +1,13 @@
+/// <reference path='fourslash.ts'/>
+
+//// type constructorType<T1, T2> = new <T/*1*/, /*2*/
+
+goTo.marker("1");
+verify.memberListContains("T");
+verify.memberListContains("T1");
+verify.memberListContains("T2");
+
+goTo.marker("2");
+verify.memberListContains("T");
+verify.memberListContains("T1");
+verify.memberListContains("T2");

tests/cases/fourslash/quickInfoDisplayPartsTypeParameterInFunctionLikeInTypeAlias.ts

@@ -0,0 +1,22 @@
+/// <reference path='fourslash.ts'/>
+
+//// type MixinCtor<A> = new () => /*0*/A & { constructor: MixinCtor</*1*/A> };
+//// type MixinCtor<A> = new () => A & { constructor: { constructor: MixinCtor</*2*/A> } };
+
+let typeAliashDisplayParts = [{ text: "type", kind: "keyword" }, { text: " ", kind: "space" }, { text: "MixinCtor", kind: "aliasName" },
+    { text: "<", kind: "punctuation" }, { text: "A", kind: "typeParameterName" }, { text: ">", kind: "punctuation" }];
+
+let typeParameterDisplayParts = [{ text: "(", kind: "punctuation" }, { text: "type parameter", kind: "text" }, { text: ")", kind: "punctuation" }, { text: " ", kind: "space" },
+    { text: "A", kind: "typeParameterName" }, { text: " ", kind: "space" }, { text: "in", kind: "keyword" }, { text: " ", kind: "space" }];
+
+goTo.marker('0');
+verify.verifyQuickInfoDisplayParts("type parameter", "", { start: test.markerByName("0").position, length: "A".length },
+    typeParameterDisplayParts.concat(typeAliashDisplayParts), []);
+
+goTo.marker('1');
+verify.verifyQuickInfoDisplayParts("type parameter", "", { start: test.markerByName("1").position, length: "A".length },
+    typeParameterDisplayParts.concat(typeAliashDisplayParts), []);;
+
+goTo.marker('2');
+verify.verifyQuickInfoDisplayParts("type parameter", "", { start: test.markerByName("2").position, length: "A".length },
+    typeParameterDisplayParts.concat(typeAliashDisplayParts), []);

tests/cases/fourslash/quickInfoDisplayPartsTypeParameterInTypeAlias.ts

@@ -3,9 +3,6 @@
 ////type /*0*/List</*1*/T> = /*2*/T[]
 ////type /*3*/List2</*4*/T extends string> = /*5*/T[];
 
-type List2<T extends string> = T[];
-
-type L<T> = T[]
 let typeAliashDisplayParts = [{ text: "type", kind: "keyword" }, { text: " ", kind: "space" }, { text: "List", kind: "aliasName" },
     { text: "<", kind: "punctuation" }, { text: "T", kind: "typeParameterName" }, { text: ">", kind: "punctuation" }];
 

tests/cases/fourslash/quickInfoDisplayPartsTypeParameterOfFunctionLikeInTypeAlias.ts

@@ -0,0 +1,41 @@
+/// <reference path='fourslash.ts'/>
+
+//// type jamming<A> = new </*0*/A>() => jamming</*1*/A>;
+//// type jamming<A> = (new <A>() => jamming<A>) & { constructor: /*2*/A };
+//// type jamming<A> = new <A>() => jamming<A> & { constructor: /*3*/A };
+
+let typeAliashDisplayParts = [{ text: "type", kind: "keyword" }, { text: " ", kind: "space" }, { text: "jamming", kind: "aliasName" },
+    { text: "<", kind: "punctuation" }, { text: "A", kind: "typeParameterName" }, { text: ">", kind: "punctuation" }];
+
+let typeParameterDisplayParts = [{ text: "(", kind: "punctuation" }, { text: "type parameter", kind: "text" }, { text: ")", kind: "punctuation" }, { text: " ", kind: "space" },
+    { text: "A", kind: "typeParameterName" }, { text: " ", kind: "space" }, { text: "in", kind: "keyword" }, { text: " ", kind: "space" }];
+
+let constructorTypeDisplayParts = [{ text: "<", kind: "punctuation" }, { text: "A", kind: "typeParameterName" }, { text: ">", kind: "punctuation" },
+    { text: "(", kind: "punctuation" }, { text: ")", kind: "punctuation" }, { text: ":", kind: "punctuation" }, { text: " ", kind: "space" },
+    { text: "new", kind: "keyword" }, { "text": " ", kind: "space" }, { text: "<", kind: "punctuation" }, { text: "A", kind: "typeParameterName" }, 
+    { text: ">", kind: "punctuation" }, { text: "(", kind: "punctuation" }, { text: ")", kind: "punctuation" }, {"text": " ", kind: "space" },
+    { text: "=>", kind: "punctuation" }, { "text": " ", kind: "space" }, { text: "jamming", kind: "aliasName" }];
+
+let constructorTypeWithLongReturnTypeDisplayParts = [{ "text": "<", kind: "punctuation" }, { "text": "A", kind: "typeParameterName" }, { "text": ">", kind: "punctuation" },
+    { "text": "(", kind: "punctuation" }, { "text": ")", kind: "punctuation" }, { "text": ":", kind: "punctuation" }, { "text": " ", kind: "space" }, { "text": "(", kind: "punctuation" },
+    { "text": "new", kind: "keyword" }, { "text": " ", kind: "space" }, { "text": "<", kind: "punctuation" }, { "text": "A", kind: "typeParameterName" }, { "text": ">", kind: "punctuation" },
+    { "text": "(", kind: "punctuation" }, { "text": ")", kind: "punctuation" }, { "text": " ", kind: "space" }, { "text": "=>", kind: "punctuation" }, { "text": " ", kind: "space" },
+    { "text": "jamming", kind: "aliasName" }, { "text": ")", kind: "punctuation" }, { "text": " ", kind: "space" }, { "text": "&", kind: "punctuation" }, { "text": " ", kind: "space" },
+    { "text": "{", kind: "punctuation" }, { "text": "\n", kind: "lineBreak" }, { "text": "    ", kind: "space" }, { "text": "constructor", kind: "propertyName" }, { "text": ":", kind: "punctuation" },
+    { "text": " ", kind: "space" }, { "text": "A", kind: "typeParameterName" }, {"text":";", kind: "punctuation" }, {"text":"\n", kind: "lineBreak" }, {"text":"}", kind: "punctuation" }];
+
+goTo.marker('0');
+verify.verifyQuickInfoDisplayParts("type parameter", "", { start: test.markerByName("0").position, length: "A".length },
+    typeParameterDisplayParts.concat(constructorTypeDisplayParts), []);
+
+goTo.marker('1');
+verify.verifyQuickInfoDisplayParts("type parameter", "", { start: test.markerByName("1").position, length: "A".length },
+    typeParameterDisplayParts.concat(constructorTypeDisplayParts), []);
+
+goTo.marker('2');
+verify.verifyQuickInfoDisplayParts("type parameter", "", { start: test.markerByName("2").position, length: "A".length },
+    typeParameterDisplayParts.concat(typeAliashDisplayParts), []);
+
+goTo.marker('3');
+verify.verifyQuickInfoDisplayParts("type parameter", "", { start: test.markerByName("3").position, length: "A".length },
+    typeParameterDisplayParts.concat(constructorTypeWithLongReturnTypeDisplayParts), []);