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Distribute index over mapped types when normalizing types #55130

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c009620
Distribute index over mapped types when normalizing types
Andarist Jul 24, 2023
35be879
Merge remote-tracking branch 'origin/main' into fix/too-eager-indexed…
Andarist Aug 17, 2023
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17 changes: 12 additions & 5 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -17870,8 +17870,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
(type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.Index | TypeFlags.StringMapping) && !isPatternLiteralType(type) ? ObjectFlags.IsGenericIndexType : 0);
}

function getSimplifiedType(type: Type, writing: boolean): Type {
return type.flags & TypeFlags.IndexedAccess ? getSimplifiedIndexedAccessType(type as IndexedAccessType, writing) :
function getSimplifiedType(type: Type, writing: boolean, distributeIndexOverMappedType = false): Type {
return type.flags & TypeFlags.IndexedAccess ? getSimplifiedIndexedAccessType(type as IndexedAccessType, writing, distributeIndexOverMappedType) :
type.flags & TypeFlags.Conditional ? getSimplifiedConditionalType(type as ConditionalType, writing) :
type;
}
Expand All @@ -17898,8 +17898,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// Transform an indexed access to a simpler form, if possible. Return the simpler form, or return
// the type itself if no transformation is possible. The writing flag indicates that the type is
// the target of an assignment.
function getSimplifiedIndexedAccessType(type: IndexedAccessType, writing: boolean): Type {
const cache = writing ? "simplifiedForWriting" : "simplifiedForReading";
function getSimplifiedIndexedAccessType(type: IndexedAccessType, writing: boolean, distributeIndexOverMappedType: boolean): Type {
const cache = writing ? "simplifiedForWriting" : `simplifiedForReading${distributeIndexOverMappedType ? "D" : ""}` as const;
if (type[cache]) {
return type[cache] === circularConstraintType ? type : type[cache]!;
}
Expand Down Expand Up @@ -17941,6 +17941,13 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// For example, for an index access { [P in K]: Box<T[P]> }[X], we construct the type Box<T[X]>.
if (isGenericMappedType(objectType)) {
if (!getNameTypeFromMappedType(objectType) || isFilteringMappedType(objectType)) {
if (distributeIndexOverMappedType && !writing) {
const indexConstraint = indexType.flags & TypeFlags.Instantiable && getBaseConstraintOfType(indexType);
if (indexConstraint && indexConstraint.flags & TypeFlags.Union) {
return type[cache] = getSimplifiedType(getIndexedAccessType(objectType, getIntersectionType([indexType, indexConstraint])), writing);
}
}

return type[cache] = mapType(substituteIndexedMappedType(objectType, type.indexType), t => getSimplifiedType(t, writing));
}
}
Expand Down Expand Up @@ -20593,7 +20600,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).node ? createTypeReference((type as TypeReference).target, getTypeArguments(type as TypeReference)) : getSingleBaseForNonAugmentingSubtype(type) || type :
type.flags & TypeFlags.UnionOrIntersection ? getNormalizedUnionOrIntersectionType(type as UnionOrIntersectionType, writing) :
type.flags & TypeFlags.Substitution ? writing ? (type as SubstitutionType).baseType : getSubstitutionIntersection(type as SubstitutionType) :
type.flags & TypeFlags.Simplifiable ? getSimplifiedType(type, writing) :
type.flags & TypeFlags.Simplifiable ? getSimplifiedType(type, writing, /*distributeIndexOverMappedType*/ true) :
type;
if (t === type) return t;
type = t;
Expand Down
1 change: 1 addition & 0 deletions src/compiler/types.ts
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Expand Up @@ -6555,6 +6555,7 @@ export interface IndexedAccessType extends InstantiableType {
constraint?: Type;
simplifiedForReading?: Type;
simplifiedForWriting?: Type;
simplifiedForReadingD?: Type;
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@weswigham weswigham Sep 13, 2023 •
edited
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Maybe D -> Distributive here, if this gets kept.

}

export type TypeVariable = TypeParameter | IndexedAccessType;
Expand Down
1 change: 1 addition & 0 deletions tests/baselines/reference/api/typescript.d.ts
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Expand Up @@ -7209,6 +7209,7 @@ declare namespace ts {
constraint?: Type;
simplifiedForReading?: Type;
simplifiedForWriting?: Type;
simplifiedForReadingD?: Type;
}
type TypeVariable = TypeParameter | IndexedAccessType;
interface IndexType extends InstantiableType {
Expand Down
60 changes: 26 additions & 34 deletions tests/baselines/reference/conditionalTypes1.errors.txt
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Expand Up @@ -8,7 +8,7 @@ conditionalTypes1.ts(17,5): error TS2322: Type 'T' is not assignable to type 'No
Type 'T' is not assignable to type '{}'.
Type 'string | undefined' is not assignable to type '{}'.
Type 'undefined' is not assignable to type '{}'.
conditionalTypes1.ts(24,5): error TS2322: Type 'T[keyof T] | undefined' is not assignable to type 'NonNullable<Partial<T>[keyof T]>'.
conditionalTypes1.ts(24,5): error TS2322: Type 'T[keyof T & string] | T[keyof T & number] | T[keyof T & symbol] | undefined' is not assignable to type 'NonNullable<Partial<T>[keyof T]>'.
Type 'undefined' is not assignable to type 'T[keyof T] & {}'.
Type 'undefined' is not assignable to type 'T[keyof T]'.
'T[keyof T]' could be instantiated with an arbitrary type which could be unrelated to 'undefined'.
Expand All @@ -25,32 +25,28 @@ conditionalTypes1.ts(104,5): error TS2322: Type 'NonFunctionProperties<T>' is no
'T' could be instantiated with an arbitrary type which could be unrelated to 'NonFunctionProperties<T>'.
conditionalTypes1.ts(106,5): error TS2322: Type 'NonFunctionProperties<T>' is not assignable to type 'FunctionProperties<T>'.
Type 'FunctionPropertyNames<T>' is not assignable to type 'NonFunctionPropertyNames<T>'.
Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T' is not assignable to type 'never'.
Type 'string | number | symbol' is not assignable to type 'never'.
Type 'string' is not assignable to type 'never'.
Type 'T[keyof T & string] extends Function ? keyof T & string : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T & string' is not assignable to type 'never'.
conditionalTypes1.ts(108,5): error TS2322: Type 'FunctionProperties<T>' is not assignable to type 'NonFunctionProperties<T>'.
Type 'NonFunctionPropertyNames<T>' is not assignable to type 'FunctionPropertyNames<T>'.
Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T' is not assignable to type 'never'.
Type 'T[keyof T & string] extends Function ? never : keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T & string' is not assignable to type 'never'.
conditionalTypes1.ts(114,5): error TS2322: Type 'keyof T' is not assignable to type 'FunctionPropertyNames<T>'.
Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
conditionalTypes1.ts(115,5): error TS2322: Type 'NonFunctionPropertyNames<T>' is not assignable to type 'FunctionPropertyNames<T>'.
Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T' is not assignable to type 'never'.
Type 'string | number | symbol' is not assignable to type 'never'.
Type 'string' is not assignable to type 'never'.
Type 'T[keyof T & string] extends Function ? never : keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
Type 'keyof T & string' is not assignable to type 'never'.
conditionalTypes1.ts(116,5): error TS2322: Type 'keyof T' is not assignable to type 'NonFunctionPropertyNames<T>'.
Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
conditionalTypes1.ts(117,5): error TS2322: Type 'FunctionPropertyNames<T>' is not assignable to type 'NonFunctionPropertyNames<T>'.
Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T' is not assignable to type 'never'.
Type 'T[keyof T & string] extends Function ? keyof T & string : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
Type 'keyof T & string' is not assignable to type 'never'.
conditionalTypes1.ts(134,10): error TS2540: Cannot assign to 'id' because it is a read-only property.
conditionalTypes1.ts(135,5): error TS2542: Index signature in type 'DeepReadonlyArray<Part>' only permits reading.
conditionalTypes1.ts(136,22): error TS2540: Cannot assign to 'id' because it is a read-only property.
Expand Down Expand Up @@ -108,7 +104,7 @@ conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to t
x = y;
y = x; // Error
~
!!! error TS2322: Type 'T[keyof T] | undefined' is not assignable to type 'NonNullable<Partial<T>[keyof T]>'.
!!! error TS2322: Type 'T[keyof T & string] | T[keyof T & number] | T[keyof T & symbol] | undefined' is not assignable to type 'NonNullable<Partial<T>[keyof T]>'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[keyof T] & {}'.
!!! error TS2322: Type 'undefined' is not assignable to type 'T[keyof T]'.
!!! error TS2322: 'T[keyof T]' could be instantiated with an arbitrary type which could be unrelated to 'undefined'.
Expand Down Expand Up @@ -211,21 +207,17 @@ conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to t
~
!!! error TS2322: Type 'NonFunctionProperties<T>' is not assignable to type 'FunctionProperties<T>'.
!!! error TS2322: Type 'FunctionPropertyNames<T>' is not assignable to type 'NonFunctionPropertyNames<T>'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'never'.
!!! error TS2322: Type 'string' is not assignable to type 'never'.
!!! error TS2322: Type 'T[keyof T & string] extends Function ? keyof T & string : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'never'.
z = x;
z = y; // Error
~
!!! error TS2322: Type 'FunctionProperties<T>' is not assignable to type 'NonFunctionProperties<T>'.
!!! error TS2322: Type 'NonFunctionPropertyNames<T>' is not assignable to type 'FunctionPropertyNames<T>'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
!!! error TS2322: Type 'T[keyof T & string] extends Function ? never : keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'never'.
}

function f8<T>(x: keyof T, y: FunctionPropertyNames<T>, z: NonFunctionPropertyNames<T>) {
Expand All @@ -239,10 +231,9 @@ conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to t
y = z; // Error
~
!!! error TS2322: Type 'NonFunctionPropertyNames<T>' is not assignable to type 'FunctionPropertyNames<T>'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'never'.
!!! error TS2322: Type 'string' is not assignable to type 'never'.
!!! error TS2322: Type 'T[keyof T & string] extends Function ? never : keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? keyof T : never'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'never'.
z = x; // Error
~
!!! error TS2322: Type 'keyof T' is not assignable to type 'NonFunctionPropertyNames<T>'.
Expand All @@ -251,8 +242,9 @@ conditionalTypes1.ts(288,43): error TS2322: Type 'T95<U>' is not assignable to t
z = y; // Error
~
!!! error TS2322: Type 'FunctionPropertyNames<T>' is not assignable to type 'NonFunctionPropertyNames<T>'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T' is not assignable to type 'never'.
!!! error TS2322: Type 'T[keyof T & string] extends Function ? keyof T & string : never' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'T[keyof T] extends Function ? never : keyof T'.
!!! error TS2322: Type 'keyof T & string' is not assignable to type 'never'.
}

type DeepReadonly<T> =
Expand Down
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