Expand constraint suggestion related span and add quick fix

Author: weswigham

src/compiler/checker.ts

@@ -18792,8 +18792,9 @@ namespace ts {
                     return;
                 }
                 reportRelationError(headMessage, source, target);
-                if (strictNullChecks && source.flags & TypeFlags.TypeVariable && source.symbol?.declarations?.[0] && !getConstraintOfType(source as TypeVariable) && isRelatedTo(emptyObjectType, extractTypesOfKind(target, ~TypeFlags.NonPrimitive))) {
-                    associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_probably_needs_an_extends_object_constraint));
+                if (source.flags & TypeFlags.TypeParameter && source.symbol?.declarations?.[0] && !getConstraintOfType(source as TypeVariable)) {
+                    const targetConstraintString = typeToString(target, source.symbol.declarations[0]);
+                    associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_might_need_an_extends_0_constraint, targetConstraintString));
                 }
             }
 

src/compiler/diagnosticMessages.json

@@ -1530,7 +1530,7 @@
         "category": "Error",
         "code": 2207
     },
-    "This type parameter probably needs an `extends object` constraint.": {
+    "This type parameter might need an `extends {0}` constraint.": {
         "category": "Error",
         "code": 2208
     },
@@ -1543,6 +1543,10 @@
         "category": "Error",
         "code": 2210
     },
+    "Add `extends` constraint.": {
+        "category": "Message",
+        "code": 2211
+    },
 
     "Duplicate identifier '{0}'.": {
         "category": "Error",

src/services/codefixes/fixAddMissingConstraint.ts

@@ -0,0 +1,66 @@
+/* @internal */
+namespace ts.codefix {
+    const fixId = "addMissingConstraint";
+    const errorCodes = [
+        // We want errors this could be attached to:
+        // Diagnostics.This_type_parameter_probably_needs_an_extends_0_constraint
+        Diagnostics.Type_0_is_not_comparable_to_type_1.code,
+        Diagnostics.Type_0_is_not_assignable_to_type_1_Two_different_types_with_this_name_exist_but_they_are_unrelated.code,
+        Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties.code,
+        Diagnostics.Type_0_is_not_assignable_to_type_1.code,
+        Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties.code,
+        Diagnostics.Property_0_is_incompatible_with_index_signature.code,
+        Diagnostics.Property_0_in_type_1_is_not_assignable_to_type_2.code,
+    ];
+    registerCodeFix({
+        errorCodes,
+        getCodeActions(context) {
+            const { sourceFile, span, program } = context;
+            const related = getDiagnosticRelatedInfo(program, sourceFile, span);
+            if (!related) {
+                return;
+            }
+            const changes = textChanges.ChangeTracker.with(context, t => addMissingConstraint(t, related));
+            return [createCodeFixAction(fixId, changes, Diagnostics.Add_extends_constraint, fixId, Diagnostics.Add_missing_new_operator_to_all_calls)];
+        },
+        fixIds: [fixId],
+        getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => {
+            const info = getDiagnosticRelatedInfo(context.program, context.sourceFile, diag);
+            if (!info) return;
+            return addMissingConstraint(changes, info);
+        }),
+    });
+
+    function getDiagnosticRelatedInfo(program: Program, sourceFile: SourceFile, span: TextSpan) {
+        const diags = program.getSemanticDiagnostics(sourceFile).filter(diag => diag.start === span.start && diag.length === span.length);
+        if (!length(diags)) return;
+        const diag = diags[0];
+        if (!diag.relatedInformation) return;
+        const related = filter(diag.relatedInformation, related => related.code === Diagnostics.This_type_parameter_might_need_an_extends_0_constraint.code)[0];
+        if (!related) return;
+        return related;
+    }
+
+    function addMissingConstraint(changes: textChanges.ChangeTracker, related: DiagnosticRelatedInformation): void {
+        let decl = findAncestorMatchingSpan(related.file!, related as TextSpan);
+        if (!decl) return;
+        if (isIdentifier(decl) && isTypeParameterDeclaration(decl.parent)) {
+            decl = decl.parent;
+        }
+        if (!isTypeParameterDeclaration(decl) || isMappedTypeNode(decl.parent)) return; // should only issue fix on type parameters written using `extends`
+        const newConstraint = flattenDiagnosticMessageText(related.messageText, "\n", 0).match(/`extends (.*)`/);
+        if (!newConstraint) return;
+        const newConstraintText = newConstraint[1];
+
+        changes.insertText(related.file!, related.start! + related.length!, ` extends ${newConstraintText}`);
+    }
+
+    function findAncestorMatchingSpan(sourceFile: SourceFile, span: TextSpan): Node {
+        let token = getTokenAtPosition(sourceFile, span.start);
+        const end = textSpanEnd(span);
+        while (token.end < end) {
+            token = token.parent;
+        }
+        return token;
+    }
+}

src/services/tsconfig.json

@@ -68,6 +68,7 @@
         "codefixes/convertLiteralTypeToMappedType.ts",
         "codefixes/fixClassIncorrectlyImplementsInterface.ts",
         "codefixes/importFixes.ts",
+        "codefixes/fixAddMissingConstraint.ts",
         "codefixes/fixOverrideModifier.ts",
         "codefixes/fixNoPropertyAccessFromIndexSignature.ts",
         "codefixes/fixImplicitThis.ts",

tests/baselines/reference/assignmentCompatWithCallSignatures3.errors.txt

@@ -114,27 +114,31 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type '(x: number) => number[]' is not assignable to type '<T>(x: T) => T[]'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts:45:9: This type parameter might need an `extends number` constraint.
     var b2: <T>(x: T) => string[]; 
     a2 = b2; // ok 
     b2 = a2; // ok
     ~~
 !!! error TS2322: Type '(x: number) => string[]' is not assignable to type '<T>(x: T) => string[]'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts:48:10: This type parameter might need an `extends number` constraint.
     var b3: <T>(x: T) => T; 
     a3 = b3; // ok
     b3 = a3; // ok
     ~~
 !!! error TS2322: Type '(x: number) => void' is not assignable to type '<T>(x: T) => T'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts:51:10: This type parameter might need an `extends number` constraint.
     var b4: <T, U>(x: T, y: U) => T; 
     a4 = b4; // ok
     b4 = a4; // ok
     ~~
 !!! error TS2322: Type '(x: string, y: number) => string' is not assignable to type '<T, U>(x: T, y: U) => T'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts:54:10: This type parameter might need an `extends string` constraint.
     var b5: <T, U>(x: (arg: T) => U) => T; 
     a5 = b5; // ok
     b5 = a5; // ok
@@ -227,6 +231,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:     Type '{ a: T; b: T; }' is not assignable to type '{ a: string; b: number; }'.
 !!! error TS2322:       Types of property 'a' are incompatible.
 !!! error TS2322:         Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures3.ts:84:11: This type parameter might need an `extends string` constraint.
     var b15: <T>(x: T) => T[]; 
     a15 = b15; // ok
     b15 = a15; // ok

tests/baselines/reference/assignmentCompatWithCallSignatures4.errors.txt

@@ -113,6 +113,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type '(x: number) => string[]' is not assignable to type '<T, U>(x: T) => U[]'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts:43:18: This type parameter might need an `extends number` constraint.
 
             var b7: <T extends Base, U extends Derived, V extends Derived2>(x: (arg: T) => U) => (r: T) => V;
             a7 = b7;
@@ -181,6 +182,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:     Type '{ a: T; b: T; }' is not assignable to type '{ a: string; b: number; }'.
 !!! error TS2322:       Types of property 'a' are incompatible.
 !!! error TS2322:         Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts:68:19: This type parameter might need an `extends string` constraint.
 
             var b15a: <T extends Base>(x: { a: T; b: T }) => number; 
             a15 = b15a;
@@ -223,6 +225,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type '<T>(x: T) => T[]' is not assignable to type '<T>(x: T) => string[]'.
 !!! error TS2322:   Type 'T[]' is not assignable to type 'string[]'.
 !!! error TS2322:     Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts:88:18: This type parameter might need an `extends string` constraint.
 
             // target type has generic call signature
             var a3: <T>(x: T) => string[];
@@ -232,6 +235,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type '<T>(x: T) => T[]' is not assignable to type '<T>(x: T) => string[]'.
 !!! error TS2322:   Type 'T[]' is not assignable to type 'string[]'.
 !!! error TS2322:     Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures4.ts:93:18: This type parameter might need an `extends string` constraint.
             b3 = a3;
             ~~
 !!! error TS2322: Type '<T>(x: T) => string[]' is not assignable to type '<T>(x: T) => T[]'.

tests/baselines/reference/assignmentCompatWithCallSignatures5.errors.txt

@@ -84,6 +84,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:       Types of property 'foo' are incompatible.
 !!! error TS2322:         Type 'U' is not assignable to type 'T'.
 !!! error TS2322:           'T' could be instantiated with an arbitrary type which could be unrelated to 'U'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures5.ts:50:14: This type parameter might need an `extends T` constraint.
     var b15: <U, V>(x: { a: U; b: V; }) => U[]; 
     a15 = b15; // ok, T = U, T = V
     b15 = a15; // ok
@@ -94,6 +95,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:       Types of property 'b' are incompatible.
 !!! error TS2322:         Type 'V' is not assignable to type 'U'.
 !!! error TS2322:           'U' could be instantiated with an arbitrary type which could be unrelated to 'V'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures5.ts:53:14: This type parameter might need an `extends U` constraint.
     var b16: <T>(x: { a: T; b: T }) => T[]; 
     a15 = b16; // ok
     b15 = a16; // ok
@@ -103,6 +105,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:     Type '{ a: U; b: V; }' is not assignable to type '{ a: Base; b: Base; }'.
 !!! error TS2322:       Types of property 'a' are incompatible.
 !!! error TS2322:         Type 'U' is not assignable to type 'Base'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures5.ts:53:11: This type parameter might need an `extends Base` constraint.
     var b17: <T>(x: (a: T) => T) => T[]; 
     a17 = b17; // ok
     b17 = a17; // ok

tests/baselines/reference/assignmentCompatWithCallSignatures6.errors.txt

@@ -65,6 +65,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:       Types of property 'foo' are incompatible.
 !!! error TS2322:         Type 'U' is not assignable to type 'T'.
 !!! error TS2322:           'T' could be instantiated with an arbitrary type which could be unrelated to 'U'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures6.ts:37:14: This type parameter might need an `extends T` constraint.
     var b16: <T>(x: { a: T; b: T }) => T[]; 
     x.a16 = b16;
     b16 = x.a16;
@@ -73,4 +74,5 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type '{ a: T; b: T; }' is not assignable to type '{ a: Base; b: Base; }'.
 !!! error TS2322:       Types of property 'a' are incompatible.
-!!! error TS2322:         Type 'T' is not assignable to type 'Base'.
+!!! error TS2322:         Type 'T' is not assignable to type 'Base'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithCallSignatures6.ts:40:11: This type parameter might need an `extends Base` constraint.

tests/baselines/reference/assignmentCompatWithConstructSignatures3.errors.txt

@@ -114,27 +114,31 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'new (x: number) => number[]' is not assignable to type 'new <T>(x: T) => T[]'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures3.ts:45:13: This type parameter might need an `extends number` constraint.
     var b2: new <T>(x: T) => string[]; 
     a2 = b2; // ok 
     b2 = a2; // ok
     ~~
 !!! error TS2322: Type 'new (x: number) => string[]' is not assignable to type 'new <T>(x: T) => string[]'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures3.ts:48:14: This type parameter might need an `extends number` constraint.
     var b3: new <T>(x: T) => T; 
     a3 = b3; // ok
     b3 = a3; // ok
     ~~
 !!! error TS2322: Type 'new (x: number) => void' is not assignable to type 'new <T>(x: T) => T'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures3.ts:51:14: This type parameter might need an `extends number` constraint.
     var b4: new <T, U>(x: T, y: U) => T; 
     a4 = b4; // ok
     b4 = a4; // ok
     ~~
 !!! error TS2322: Type 'new (x: string, y: number) => string' is not assignable to type 'new <T, U>(x: T, y: U) => T'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures3.ts:54:14: This type parameter might need an `extends string` constraint.
     var b5: new <T, U>(x: (arg: T) => U) => T; 
     a5 = b5; // ok
     b5 = a5; // ok
@@ -227,6 +231,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:     Type '{ a: T; b: T; }' is not assignable to type '{ a: string; b: number; }'.
 !!! error TS2322:       Types of property 'a' are incompatible.
 !!! error TS2322:         Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures3.ts:84:15: This type parameter might need an `extends string` constraint.
     var b15: new <T>(x: T) => T[]; 
     a15 = b15; // ok
     b15 = a15; // ok

tests/baselines/reference/assignmentCompatWithConstructSignatures4.errors.txt

@@ -129,6 +129,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'new (x: number) => string[]' is not assignable to type 'new <T, U>(x: T) => U[]'.
 !!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'number'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts:43:22: This type parameter might need an `extends number` constraint.
 
             var b7: new <T extends Base, U extends Derived, V extends Derived2>(x: (arg: T) => U) => (r: T) => V;
             a7 = b7; // ok
@@ -197,6 +198,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322:     Type '{ a: T; b: T; }' is not assignable to type '{ a: string; b: number; }'.
 !!! error TS2322:       Types of property 'a' are incompatible.
 !!! error TS2322:         Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts:68:23: This type parameter might need an `extends string` constraint.
 
             var b15a: new <T extends Base>(x: { a: T; b: T }) => number; 
             a15 = b15a; // ok
@@ -259,6 +261,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'new <T>(x: T) => T[]' is not assignable to type 'new <T>(x: T) => string[]'.
 !!! error TS2322:   Type 'T[]' is not assignable to type 'string[]'.
 !!! error TS2322:     Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts:88:22: This type parameter might need an `extends string` constraint.
 
             // target type has generic call signature
             var a3: new <T>(x: T) => string[];
@@ -268,6 +271,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'new <T>(x: T) => T[]' is not assignable to type 'new <T>(x: T) => string[]'.
 !!! error TS2322:   Type 'T[]' is not assignable to type 'string[]'.
 !!! error TS2322:     Type 'T' is not assignable to type 'string'.
+!!! related TS2208 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithConstructSignatures4.ts:93:22: This type parameter might need an `extends string` constraint.
             b3 = a3; // ok
             ~~
 !!! error TS2322: Type 'new <T>(x: T) => string[]' is not assignable to type 'new <T>(x: T) => T[]'.