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Permit type alias variance annotations only for certain object types #48589

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merged 2 commits into from
Apr 6, 2022
Merged

Permit type alias variance annotations only for certain object types #48589

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77441a8
Permit type alias variance annotations only for certain object types
ahejlsberg Apr 5, 2022
21503fe
Accept new baselines
ahejlsberg Apr 6, 2022
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19 changes: 12 additions & 7 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -34795,14 +34795,19 @@ namespace ts {
}
if (node.parent.kind === SyntaxKind.InterfaceDeclaration || node.parent.kind === SyntaxKind.ClassDeclaration || node.parent.kind === SyntaxKind.TypeAliasDeclaration) {
const modifiers = getVarianceModifiers(typeParameter);
if (modifiers === ModifierFlags.In || modifiers === ModifierFlags.Out) {
if (modifiers) {
const symbol = getSymbolOfNode(node.parent);
const source = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSubType : markerSuperType);
const target = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSuperType : markerSubType);
const saveVarianceTypeParameter = typeParameter;
varianceTypeParameter = typeParameter;
checkTypeAssignableTo(source, target, node, Diagnostics.Type_0_is_not_assignable_to_type_1_as_implied_by_variance_annotation);
varianceTypeParameter = saveVarianceTypeParameter;
if (node.parent.kind === SyntaxKind.TypeAliasDeclaration && !(getObjectFlags(getDeclaredTypeOfSymbol(symbol)) & (ObjectFlags.Anonymous | ObjectFlags.Mapped))) {
error(node, Diagnostics.Variance_annotations_are_only_supported_in_type_aliases_for_object_function_constructor_and_mapped_types);
}
else if (modifiers === ModifierFlags.In || modifiers === ModifierFlags.Out) {
const source = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSubType : markerSuperType);
const target = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSuperType : markerSubType);
const saveVarianceTypeParameter = typeParameter;
varianceTypeParameter = typeParameter;
checkTypeAssignableTo(source, target, node, Diagnostics.Type_0_is_not_assignable_to_type_1_as_implied_by_variance_annotation);
varianceTypeParameter = saveVarianceTypeParameter;
}
}
}
addLazyDiagnostic(() => checkTypeNameIsReserved(node.name, Diagnostics.Type_parameter_name_cannot_be_0));
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4 changes: 4 additions & 0 deletions src/compiler/diagnosticMessages.json
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Expand Up @@ -2743,6 +2743,10 @@
"category": "Error",
"code": 2636
},
"Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.": {
"category": "Error",
"code": 2637
},

"Cannot augment module '{0}' with value exports because it resolves to a non-module entity.": {
"category": "Error",
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34 changes: 27 additions & 7 deletions tests/baselines/reference/varianceAnnotations.errors.txt
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Expand Up @@ -10,12 +10,15 @@ tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotati
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(29,1): error TS2322: Type 'Invariant<unknown>' is not assignable to type 'Invariant<string>'.
The types returned by 'f(...)' are incompatible between these types.
Type 'unknown' is not assignable to type 'string'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(33,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(34,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(35,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(35,17): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(36,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(40,17): error TS2636: Type 'Covariant1<super-T>' is not assignable to type 'Covariant1<sub-T>' as implied by variance annotation.
Types of property 'x' are incompatible.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(44,21): error TS2636: Type 'keyof sub-T' is not assignable to type 'keyof super-T' as implied by variance annotation.
Type 'string | number | symbol' is not assignable to type 'keyof super-T'.
Type 'string' is not assignable to type 'keyof super-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(44,21): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(46,21): error TS2636: Type 'Contravariant2<sub-T>' is not assignable to type 'Contravariant2<super-T>' as implied by variance annotation.
Types of property 'f' are incompatible.
Type '(x: sub-T) => void' is not assignable to type '(x: super-T) => void'.
Expand All @@ -37,8 +40,11 @@ tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotati
Type 'FooFn2<sub-T>' is not assignable to type 'FooFn2<super-T>'.
Type 'super-T' is not assignable to type 'sub-T'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(95,10): error TS1273: 'public' modifier cannot appear on a type parameter
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(96,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(96,17): error TS1030: 'in' modifier already seen.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(97,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(97,17): error TS1030: 'out' modifier already seen.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(98,10): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(98,14): error TS1029: 'in' modifier must precede 'out' modifier.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(100,21): error TS1274: 'in' modifier can only appear on a type parameter of a class, interface or type alias
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts(101,21): error TS1274: 'out' modifier can only appear on a type parameter of a class, interface or type alias
Expand All @@ -60,7 +66,7 @@ tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotati
Type '{ type: "RESET"; }' is not assignable to type '{ type: "PLAY"; value: number; }'.


==== tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts (23 errors) ====
==== tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotations.ts (31 errors) ====
type Covariant<out T> = {
x: T;
}
Expand Down Expand Up @@ -110,9 +116,19 @@ tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotati
// Variance of various type constructors

type T10<out T> = T;
~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
type T11<in T> = keyof T;
~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
type T12<out T, out K extends keyof T> = T[K];
~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~~~~~~~~~~~~~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
type T13<in out T> = T[keyof T];
~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.

// Variance annotation errors

Expand All @@ -126,9 +142,7 @@ tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotati

type Contravariant1<out T> = keyof T; // Error
~~~~~
!!! error TS2636: Type 'keyof sub-T' is not assignable to type 'keyof super-T' as implied by variance annotation.
!!! error TS2636: Type 'string | number | symbol' is not assignable to type 'keyof super-T'.
!!! error TS2636: Type 'string' is not assignable to type 'keyof super-T'.
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.

type Contravariant2<out T> = { // Error
~~~~~
Expand Down Expand Up @@ -208,12 +222,18 @@ tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotati
~~~~~~
!!! error TS1273: 'public' modifier cannot appear on a type parameter
type T21<in out in T> = T; // Error
~~~~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~
!!! error TS1030: 'in' modifier already seen.
type T22<in out out T> = T; // Error
~~~~~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~~
!!! error TS1030: 'out' modifier already seen.
type T23<out in T> = T; // Error
~~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~
!!! error TS1029: 'in' modifier must precede 'out' modifier.

Expand Down
13 changes: 11 additions & 2 deletions tests/baselines/reference/varianceAnnotationsWithCircularlyReferencesError.errors.txt
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@@ -1,17 +1,26 @@
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts(1,6): error TS2456: Type alias 'T1' circularly references itself.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts(1,9): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts(1,11): error TS2300: Duplicate identifier '(Missing)'.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts(1,11): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts(1,12): error TS1359: Identifier expected. 'in' is a reserved word that cannot be used here.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts(2,6): error TS2456: Type alias 'T2' circularly references itself.
tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts(2,9): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.


==== tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts (4 errors) ====
==== tests/cases/conformance/types/typeParameters/typeParameterLists/varianceAnnotationsWithCircularlyReferencesError.ts (7 errors) ====
type T1<in in> = T1 // Error: circularly references
~~
!!! error TS2456: Type alias 'T1' circularly references itself.
~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.

!!! error TS2300: Duplicate identifier '(Missing)'.

!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
~~
!!! error TS1359: Identifier expected. 'in' is a reserved word that cannot be used here.
type T2<out out> = T2 // Error: circularly references
~~
!!! error TS2456: Type alias 'T2' circularly references itself.
!!! error TS2456: Type alias 'T2' circularly references itself.
~~~~~~~
!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.