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Merge pull request #18391 from Microsoft/fixMappedTypeInference
Inference for higher order mapped, index and lookup types
2 parents d65a3e1 + 0823eba commit d90814b

5 files changed

+284
-1
lines changed

‎src/compiler/checker.ts

+14-1
Original file line numberDiff line numberDiff line change
@@ -10387,7 +10387,7 @@ namespace ts {
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// results for union and intersection types for performance reasons.
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function couldContainTypeVariables(type: Type): boolean {
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const objectFlags = getObjectFlags(type);
10390-
return !!(type.flags & TypeFlags.TypeVariable ||
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return !!(type.flags & (TypeFlags.TypeVariable | TypeFlags.Index) ||
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objectFlags & ObjectFlags.Reference && forEach((<TypeReference>type).typeArguments, couldContainTypeVariables) ||
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objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.TypeLiteral | SymbolFlags.Class) ||
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objectFlags & ObjectFlags.Mapped ||
@@ -10555,6 +10555,13 @@ namespace ts {
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inferFromTypes(sourceTypes[i], targetTypes[i]);
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}
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}
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else if (source.flags & TypeFlags.Index && target.flags & TypeFlags.Index) {
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inferFromTypes((<IndexType>source).type, (<IndexType>target).type);
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}
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else if (source.flags & TypeFlags.IndexedAccess && target.flags & TypeFlags.IndexedAccess) {
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inferFromTypes((<IndexedAccessType>source).objectType, (<IndexedAccessType>target).objectType);
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inferFromTypes((<IndexedAccessType>source).indexType, (<IndexedAccessType>target).indexType);
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}
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else if (target.flags & TypeFlags.UnionOrIntersection) {
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const targetTypes = (<UnionOrIntersectionType>target).types;
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let typeVariableCount = 0;
@@ -10628,6 +10635,12 @@ namespace ts {
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}
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function inferFromObjectTypes(source: Type, target: Type) {
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if (isGenericMappedType(source) && isGenericMappedType(target)) {
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// The source and target types are generic types { [P in S]: X } and { [P in T]: Y }, so we infer
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// from S to T and from X to Y.
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inferFromTypes(getConstraintTypeFromMappedType(<MappedType>source), getConstraintTypeFromMappedType(<MappedType>target));
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inferFromTypes(getTemplateTypeFromMappedType(<MappedType>source), getTemplateTypeFromMappedType(<MappedType>target));
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}
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if (getObjectFlags(target) & ObjectFlags.Mapped) {
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const constraintType = getConstraintTypeFromMappedType(<MappedType>target);
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if (constraintType.flags & TypeFlags.Index) {

‎tests/baselines/reference/higherOrderMappedIndexLookupInference.js

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@@ -0,0 +1,43 @@
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//// [higherOrderMappedIndexLookupInference.ts]
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// @strict
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function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
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a = b;
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b = a;
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}
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function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
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a = b;
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b = a;
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}
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function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
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a = b;
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b = a;
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}
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// Repro from #18338
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type IdMapped<T> = { [K in keyof T]: T[K] }
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declare const f: <T>() => IdMapped<T>;
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declare const g: <U>() => { [K in keyof U]: U[K] };
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const h: typeof g = f;
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//// [higherOrderMappedIndexLookupInference.js]
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// @strict
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function f1(a, b) {
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a = b;
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b = a;
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}
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function f2(a, b) {
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a = b;
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b = a;
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}
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function f3(a, b) {
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a = b;
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b = a;
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}
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var h = f;

‎tests/baselines/reference/higherOrderMappedIndexLookupInference.symbols

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=== tests/cases/compiler/higherOrderMappedIndexLookupInference.ts ===
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// @strict
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function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
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>f1 : Symbol(f1, Decl(higherOrderMappedIndexLookupInference.ts, 0, 0))
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 2, 12))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 2, 16))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 2, 16))
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 2, 32))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 2, 37))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 2, 37))
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a = b;
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 2, 12))
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 2, 32))
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b = a;
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 2, 32))
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 2, 12))
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}
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function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
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>f2 : Symbol(f2, Decl(higherOrderMappedIndexLookupInference.ts, 5, 1))
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 7, 12))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 7, 16))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 7, 18))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 7, 16))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 7, 16))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 7, 18))
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 7, 48))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 7, 53))
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>L : Symbol(L, Decl(higherOrderMappedIndexLookupInference.ts, 7, 55))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 7, 53))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 7, 53))
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>L : Symbol(L, Decl(higherOrderMappedIndexLookupInference.ts, 7, 55))
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a = b;
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 7, 12))
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 7, 48))
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b = a;
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 7, 48))
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 7, 12))
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}
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function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
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>f3 : Symbol(f3, Decl(higherOrderMappedIndexLookupInference.ts, 10, 1))
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 12, 12))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 12, 16))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 27))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 12, 16))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 12, 16))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 27))
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 12, 49))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 12, 54))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 65))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 12, 54))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 12, 54))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 65))
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a = b;
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 12, 12))
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 12, 49))
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b = a;
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>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 12, 49))
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>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 12, 12))
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}
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// Repro from #18338
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type IdMapped<T> = { [K in keyof T]: T[K] }
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>IdMapped : Symbol(IdMapped, Decl(higherOrderMappedIndexLookupInference.ts, 15, 1))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 19, 14))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 19, 22))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 19, 14))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 19, 14))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 19, 22))
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declare const f: <T>() => IdMapped<T>;
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>f : Symbol(f, Decl(higherOrderMappedIndexLookupInference.ts, 21, 13))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 21, 18))
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>IdMapped : Symbol(IdMapped, Decl(higherOrderMappedIndexLookupInference.ts, 15, 1))
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>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 21, 18))
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declare const g: <U>() => { [K in keyof U]: U[K] };
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>g : Symbol(g, Decl(higherOrderMappedIndexLookupInference.ts, 22, 13))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 22, 18))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 22, 29))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 22, 18))
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>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 22, 18))
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>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 22, 29))
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const h: typeof g = f;
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>h : Symbol(h, Decl(higherOrderMappedIndexLookupInference.ts, 24, 5))
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>g : Symbol(g, Decl(higherOrderMappedIndexLookupInference.ts, 22, 13))
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>f : Symbol(f, Decl(higherOrderMappedIndexLookupInference.ts, 21, 13))
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‎tests/baselines/reference/higherOrderMappedIndexLookupInference.types

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=== tests/cases/compiler/higherOrderMappedIndexLookupInference.ts ===
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// @strict
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function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
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>f1 : (a: <T>() => keyof T, b: <U>() => keyof U) => void
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>a : <T>() => keyof T
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>T : T
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>T : T
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>b : <U>() => keyof U
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>U : U
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>U : U
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a = b;
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>a = b : <U>() => keyof U
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>a : <T>() => keyof T
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>b : <U>() => keyof U
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b = a;
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>b = a : <T>() => keyof T
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>b : <U>() => keyof U
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>a : <T>() => keyof T
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}
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function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
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>f2 : (a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) => void
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>a : <T, K extends keyof T>() => T[K]
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>T : T
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>K : K
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>T : T
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>T : T
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>K : K
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>b : <U, L extends keyof U>() => U[L]
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>U : U
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>L : L
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>U : U
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>U : U
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>L : L
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a = b;
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>a = b : <U, L extends keyof U>() => U[L]
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>a : <T, K extends keyof T>() => T[K]
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>b : <U, L extends keyof U>() => U[L]
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b = a;
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>b = a : <T, K extends keyof T>() => T[K]
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>b : <U, L extends keyof U>() => U[L]
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>a : <T, K extends keyof T>() => T[K]
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}
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function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
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>f3 : (a: <T>() => { [K in keyof T]: T[K]; }, b: <U>() => { [K in keyof U]: U[K]; }) => void
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>a : <T>() => { [K in keyof T]: T[K]; }
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>T : T
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>K : K
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>T : T
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>T : T
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>K : K
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>b : <U>() => { [K in keyof U]: U[K]; }
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>U : U
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>K : K
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>U : U
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>U : U
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>K : K
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a = b;
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>a = b : <U>() => { [K in keyof U]: U[K]; }
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>a : <T>() => { [K in keyof T]: T[K]; }
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>b : <U>() => { [K in keyof U]: U[K]; }
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b = a;
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>b = a : <T>() => { [K in keyof T]: T[K]; }
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>b : <U>() => { [K in keyof U]: U[K]; }
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>a : <T>() => { [K in keyof T]: T[K]; }
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}
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// Repro from #18338
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type IdMapped<T> = { [K in keyof T]: T[K] }
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>IdMapped : IdMapped<T>
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>T : T
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>K : K
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>T : T
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>T : T
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>K : K
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declare const f: <T>() => IdMapped<T>;
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>f : <T>() => IdMapped<T>
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>T : T
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>IdMapped : IdMapped<T>
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>T : T
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declare const g: <U>() => { [K in keyof U]: U[K] };
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>g : <U>() => { [K in keyof U]: U[K]; }
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>U : U
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>K : K
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>U : U
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>U : U
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>K : K
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const h: typeof g = f;
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>h : <U>() => { [K in keyof U]: U[K]; }
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>g : <U>() => { [K in keyof U]: U[K]; }
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>f : <T>() => IdMapped<T>
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‎tests/cases/compiler/higherOrderMappedIndexLookupInference.ts

+25
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// @strict
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3+
function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
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a = b;
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b = a;
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}
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function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
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a = b;
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b = a;
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}
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function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
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a = b;
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b = a;
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}
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// Repro from #18338
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type IdMapped<T> = { [K in keyof T]: T[K] }
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declare const f: <T>() => IdMapped<T>;
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declare const g: <U>() => { [K in keyof U]: U[K] };
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const h: typeof g = f;

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