WIP for 44220

Author: elibarzilay

src/compiler/checker.ts

@@ -7867,7 +7867,10 @@ namespace ts {
                             }
                         }
                     }
-                    return declarationNameToString(name);
+                    if (!(isTransientSymbol(symbol) && symbol.checkFlags & ts.CheckFlags.Mapped
+                          && isMappedTypeWithKeyofConstraintDeclaration((symbol as MappedSymbol).mappedType))) {
+                        return declarationNameToString(name);
+                    }
                 }
                 if (!declaration) {
                     declaration = symbol.declarations[0]; // Declaration may be nameless, but we'll try anyway
@@ -19078,7 +19081,9 @@ namespace ts {
                 if (props.length === 1) {
                     const propName = symbolToString(unmatchedProperty);
                     reportError(Diagnostics.Property_0_is_missing_in_type_1_but_required_in_type_2, propName, ...getTypeNamesForErrorDisplay(source, target));
-                    if (length(unmatchedProperty.declarations)) {
+                    if (length(unmatchedProperty.declarations)
+                        && !(isTransientSymbol(unmatchedProperty) && unmatchedProperty.checkFlags & ts.CheckFlags.Mapped
+                            && isMappedTypeWithKeyofConstraintDeclaration((unmatchedProperty as MappedSymbol).mappedType))) {
                         associateRelatedInfo(createDiagnosticForNode(unmatchedProperty.declarations![0], Diagnostics._0_is_declared_here, propName));
                     }
                     if (shouldSkipElaboration && errorInfo) {

tests/baselines/reference/mappedTypeErrors.errors.txt

@@ -162,7 +162,6 @@ tests/cases/conformance/types/mapped/mappedTypeErrors.ts(152,17): error TS2339:
                                                 ~~~~~~~~
 !!! error TS2345: Argument of type '{ x: number; }' is not assignable to parameter of type 'Readonly<{ x: number; y: number; }>'.
 !!! error TS2345:   Property 'y' is missing in type '{ x: number; }' but required in type 'Readonly<{ x: number; y: number; }>'.
-!!! related TS2728 tests/cases/conformance/types/mapped/mappedTypeErrors.ts:75:37: 'y' is declared here.
         let x2 = objAndReadonly({ x: 0, y: 0 }, { x: 1, y: 1 });
         let x3 = objAndReadonly({ x: 0, y: 0 }, { x: 1, y: 1, z: 1 });  // Error
                                                               ~~~~

tests/baselines/reference/mappedTypes6.errors.txt

@@ -173,7 +173,6 @@ tests/cases/conformance/types/mapped/mappedTypes6.ts(120,4): error TS2540: Canno
     x2 = { a: 1, b: 1, c: 1 };  // Error
     ~~
 !!! error TS2741: Property 'd' is missing in type '{ a: number; b: number; c: number; }' but required in type 'Required<Foo>'.
-!!! related TS2728 tests/cases/conformance/types/mapped/mappedTypes6.ts:82:5: 'd' is declared here.
     x2 = { a: 1, b: 1, c: 1, d: 1 };
 
     type Bar = {

tests/baselines/reference/recursiveMappedTypes.errors.txt

@@ -6,7 +6,7 @@ tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(11,6): error TS2456
 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(12,11): error TS2313: Type parameter 'K' has a circular constraint.
 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(20,19): error TS2589: Type instantiation is excessively deep and possibly infinite.
 tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(73,5): error TS2502: '"each"' is referenced directly or indirectly in its own type annotation.
-tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(73,13): error TS2615: Type of property '"each"' circularly references itself in mapped type '{ [P in keyof ListWidget]: undefined extends ListWidget[P] ? never : P; }'.
+tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(73,13): error TS2615: Type of property 'each' circularly references itself in mapped type '{ [P in keyof ListWidget]: undefined extends ListWidget[P] ? never : P; }'.
 
 
 ==== tests/cases/conformance/types/mapped/recursiveMappedTypes.ts (9 errors) ====
@@ -101,7 +101,7 @@ tests/cases/conformance/types/mapped/recursiveMappedTypes.ts(73,13): error TS261
         ~~~~~~
 !!! error TS2502: '"each"' is referenced directly or indirectly in its own type annotation.
                 ~~~~~~~~~~~~~~~~~
-!!! error TS2615: Type of property '"each"' circularly references itself in mapped type '{ [P in keyof ListWidget]: undefined extends ListWidget[P] ? never : P; }'.
+!!! error TS2615: Type of property 'each' circularly references itself in mapped type '{ [P in keyof ListWidget]: undefined extends ListWidget[P] ? never : P; }'.
     }
 
     type ListChild = Child<ListWidget>

tests/baselines/reference/requiredMappedTypeModifierTrumpsVariance.errors.txt

@@ -20,11 +20,9 @@ tests/cases/compiler/requiredMappedTypeModifierTrumpsVariance.ts(22,6): error TS
     A = b; // Should Error
     ~
 !!! error TS2741: Property 'a' is missing in type 'Required<{ b?: 1; x: 1; }>' but required in type 'Required<{ a?: 1; x: 1; }>'.
-!!! related TS2728 tests/cases/compiler/requiredMappedTypeModifierTrumpsVariance.ts:1:21: 'a' is declared here.
     B = a; // Should Error
     ~
 !!! error TS2741: Property 'b' is missing in type 'Required<{ a?: 1; x: 1; }>' but required in type 'Required<{ b?: 1; x: 1; }>'.
-!!! related TS2728 tests/cases/compiler/requiredMappedTypeModifierTrumpsVariance.ts:2:21: 'b' is declared here.
 
     a.b; // Property 'b' does not exist on type 'Required<{ a?: 1; x: 1; }>'.
       ~
@@ -45,13 +43,11 @@ tests/cases/compiler/requiredMappedTypeModifierTrumpsVariance.ts(22,6): error TS
 !!! error TS2322: Type 'Foo<{ b?: 1; x: 1; }>' is not assignable to type 'Foo<{ a?: 1; x: 1; }>'.
 !!! error TS2322:   Types of property 'a' are incompatible.
 !!! error TS2322:     Property 'a' is missing in type 'Required<{ b?: 1; x: 1; }>' but required in type 'Required<{ a?: 1; x: 1; }>'.
-!!! related TS2728 tests/cases/compiler/requiredMappedTypeModifierTrumpsVariance.ts:14:17: 'a' is declared here.
     BB = aa; // Should Error
     ~~
 !!! error TS2322: Type 'Foo<{ a?: 1; x: 1; }>' is not assignable to type 'Foo<{ b?: 1; x: 1; }>'.
 !!! error TS2322:   Types of property 'a' are incompatible.
 !!! error TS2322:     Property 'b' is missing in type 'Required<{ a?: 1; x: 1; }>' but required in type 'Required<{ b?: 1; x: 1; }>'.
-!!! related TS2728 tests/cases/compiler/requiredMappedTypeModifierTrumpsVariance.ts:15:17: 'b' is declared here.
 
     aa.a.b; // Property 'b' does not exist on type 'Required<{ a?: 1; x: 1; }>'.
          ~