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merged 2 commits into from
Sep 11, 2017
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Inference for higher order mapped, index and lookup types #18391

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63d746b
Higher order inference for mapped, index and lookup types
ahejlsberg Sep 11, 2017
0823eba
Add tests
ahejlsberg Sep 11, 2017
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15 changes: 14 additions & 1 deletion src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -10386,7 +10386,7 @@ namespace ts {
// results for union and intersection types for performance reasons.
function couldContainTypeVariables(type: Type): boolean {
const objectFlags = getObjectFlags(type);
return !!(type.flags & TypeFlags.TypeVariable ||
return !!(type.flags & (TypeFlags.TypeVariable | TypeFlags.Index) ||
objectFlags & ObjectFlags.Reference && forEach((<TypeReference>type).typeArguments, couldContainTypeVariables) ||
objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.TypeLiteral | SymbolFlags.Class) ||
objectFlags & ObjectFlags.Mapped ||
Expand Down Expand Up @@ -10554,6 +10554,13 @@ namespace ts {
inferFromTypes(sourceTypes[i], targetTypes[i]);
}
}
else if (source.flags & TypeFlags.Index && target.flags & TypeFlags.Index) {
inferFromTypes((<IndexType>source).type, (<IndexType>target).type);
}
else if (source.flags & TypeFlags.IndexedAccess && target.flags & TypeFlags.IndexedAccess) {
inferFromTypes((<IndexedAccessType>source).objectType, (<IndexedAccessType>target).objectType);
inferFromTypes((<IndexedAccessType>source).indexType, (<IndexedAccessType>target).indexType);
}
else if (target.flags & TypeFlags.UnionOrIntersection) {
const targetTypes = (<UnionOrIntersectionType>target).types;
let typeVariableCount = 0;
Expand Down Expand Up @@ -10627,6 +10634,12 @@ namespace ts {
}

function inferFromObjectTypes(source: Type, target: Type) {
if (isGenericMappedType(source) && isGenericMappedType(target)) {
// The source and target types are generic types { [P in S]: X } and { [P in T]: Y }, so we infer
// from S to T and from X to Y.
inferFromTypes(getConstraintTypeFromMappedType(<MappedType>source), getConstraintTypeFromMappedType(<MappedType>target));
inferFromTypes(getTemplateTypeFromMappedType(<MappedType>source), getTemplateTypeFromMappedType(<MappedType>target));
}
if (getObjectFlags(target) & ObjectFlags.Mapped) {
const constraintType = getConstraintTypeFromMappedType(<MappedType>target);
if (constraintType.flags & TypeFlags.Index) {
Expand Down
43 changes: 43 additions & 0 deletions tests/baselines/reference/higherOrderMappedIndexLookupInference.js
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@@ -0,0 +1,43 @@
//// [higherOrderMappedIndexLookupInference.ts]
// @strict

function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
a = b;
b = a;
}

function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
a = b;
b = a;
}

function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
a = b;
b = a;
}

// Repro from #18338

type IdMapped<T> = { [K in keyof T]: T[K] }

declare const f: <T>() => IdMapped<T>;
declare const g: <U>() => { [K in keyof U]: U[K] };

const h: typeof g = f;


//// [higherOrderMappedIndexLookupInference.js]
// @strict
function f1(a, b) {
a = b;
b = a;
}
function f2(a, b) {
a = b;
b = a;
}
function f3(a, b) {
a = b;
b = a;
}
var h = f;
98 changes: 98 additions & 0 deletions tests/baselines/reference/higherOrderMappedIndexLookupInference.symbols
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@@ -0,0 +1,98 @@
=== tests/cases/compiler/higherOrderMappedIndexLookupInference.ts ===
// @strict

function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
>f1 : Symbol(f1, Decl(higherOrderMappedIndexLookupInference.ts, 0, 0))
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 2, 12))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 2, 16))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 2, 16))
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 2, 32))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 2, 37))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 2, 37))

a = b;
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 2, 12))
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 2, 32))

b = a;
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 2, 32))
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 2, 12))
}

function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
>f2 : Symbol(f2, Decl(higherOrderMappedIndexLookupInference.ts, 5, 1))
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 7, 12))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 7, 16))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 7, 18))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 7, 16))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 7, 16))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 7, 18))
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 7, 48))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 7, 53))
>L : Symbol(L, Decl(higherOrderMappedIndexLookupInference.ts, 7, 55))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 7, 53))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 7, 53))
>L : Symbol(L, Decl(higherOrderMappedIndexLookupInference.ts, 7, 55))

a = b;
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 7, 12))
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 7, 48))

b = a;
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 7, 48))
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 7, 12))
}

function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
>f3 : Symbol(f3, Decl(higherOrderMappedIndexLookupInference.ts, 10, 1))
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 12, 12))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 12, 16))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 27))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 12, 16))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 12, 16))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 27))
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 12, 49))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 12, 54))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 65))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 12, 54))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 12, 54))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 12, 65))

a = b;
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 12, 12))
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 12, 49))

b = a;
>b : Symbol(b, Decl(higherOrderMappedIndexLookupInference.ts, 12, 49))
>a : Symbol(a, Decl(higherOrderMappedIndexLookupInference.ts, 12, 12))
}

// Repro from #18338

type IdMapped<T> = { [K in keyof T]: T[K] }
>IdMapped : Symbol(IdMapped, Decl(higherOrderMappedIndexLookupInference.ts, 15, 1))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 19, 14))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 19, 22))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 19, 14))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 19, 14))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 19, 22))

declare const f: <T>() => IdMapped<T>;
>f : Symbol(f, Decl(higherOrderMappedIndexLookupInference.ts, 21, 13))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 21, 18))
>IdMapped : Symbol(IdMapped, Decl(higherOrderMappedIndexLookupInference.ts, 15, 1))
>T : Symbol(T, Decl(higherOrderMappedIndexLookupInference.ts, 21, 18))

declare const g: <U>() => { [K in keyof U]: U[K] };
>g : Symbol(g, Decl(higherOrderMappedIndexLookupInference.ts, 22, 13))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 22, 18))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 22, 29))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 22, 18))
>U : Symbol(U, Decl(higherOrderMappedIndexLookupInference.ts, 22, 18))
>K : Symbol(K, Decl(higherOrderMappedIndexLookupInference.ts, 22, 29))

const h: typeof g = f;
>h : Symbol(h, Decl(higherOrderMappedIndexLookupInference.ts, 24, 5))
>g : Symbol(g, Decl(higherOrderMappedIndexLookupInference.ts, 22, 13))
>f : Symbol(f, Decl(higherOrderMappedIndexLookupInference.ts, 21, 13))

104 changes: 104 additions & 0 deletions tests/baselines/reference/higherOrderMappedIndexLookupInference.types
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=== tests/cases/compiler/higherOrderMappedIndexLookupInference.ts ===
// @strict

function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
>f1 : (a: <T>() => keyof T, b: <U>() => keyof U) => void
>a : <T>() => keyof T
>T : T
>T : T
>b : <U>() => keyof U
>U : U
>U : U

a = b;
>a = b : <U>() => keyof U
>a : <T>() => keyof T
>b : <U>() => keyof U

b = a;
>b = a : <T>() => keyof T
>b : <U>() => keyof U
>a : <T>() => keyof T
}

function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
>f2 : (a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) => void
>a : <T, K extends keyof T>() => T[K]
>T : T
>K : K
>T : T
>T : T
>K : K
>b : <U, L extends keyof U>() => U[L]
>U : U
>L : L
>U : U
>U : U
>L : L

a = b;
>a = b : <U, L extends keyof U>() => U[L]
>a : <T, K extends keyof T>() => T[K]
>b : <U, L extends keyof U>() => U[L]

b = a;
>b = a : <T, K extends keyof T>() => T[K]
>b : <U, L extends keyof U>() => U[L]
>a : <T, K extends keyof T>() => T[K]
}

function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
>f3 : (a: <T>() => { [K in keyof T]: T[K]; }, b: <U>() => { [K in keyof U]: U[K]; }) => void
>a : <T>() => { [K in keyof T]: T[K]; }
>T : T
>K : K
>T : T
>T : T
>K : K
>b : <U>() => { [K in keyof U]: U[K]; }
>U : U
>K : K
>U : U
>U : U
>K : K

a = b;
>a = b : <U>() => { [K in keyof U]: U[K]; }
>a : <T>() => { [K in keyof T]: T[K]; }
>b : <U>() => { [K in keyof U]: U[K]; }

b = a;
>b = a : <T>() => { [K in keyof T]: T[K]; }
>b : <U>() => { [K in keyof U]: U[K]; }
>a : <T>() => { [K in keyof T]: T[K]; }
}

// Repro from #18338

type IdMapped<T> = { [K in keyof T]: T[K] }
>IdMapped : IdMapped<T>
>T : T
>K : K
>T : T
>T : T
>K : K

declare const f: <T>() => IdMapped<T>;
>f : <T>() => IdMapped<T>
>T : T
>IdMapped : IdMapped<T>
>T : T

declare const g: <U>() => { [K in keyof U]: U[K] };
>g : <U>() => { [K in keyof U]: U[K]; }
>U : U
>K : K
>U : U
>U : U
>K : K

const h: typeof g = f;
>h : <U>() => { [K in keyof U]: U[K]; }
>g : <U>() => { [K in keyof U]: U[K]; }
>f : <T>() => IdMapped<T>

25 changes: 25 additions & 0 deletions tests/cases/compiler/higherOrderMappedIndexLookupInference.ts
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@@ -0,0 +1,25 @@
// @strict

function f1(a: <T>() => keyof T, b: <U>() => keyof U) {
a = b;
b = a;
}

function f2(a: <T, K extends keyof T>() => T[K], b: <U, L extends keyof U>() => U[L]) {
a = b;
b = a;
}

function f3(a: <T>() => { [K in keyof T]: T[K] }, b: <U>() => { [K in keyof U]: U[K] }) {
a = b;
b = a;
}

// Repro from #18338

type IdMapped<T> = { [K in keyof T]: T[K] }

declare const f: <T>() => IdMapped<T>;
declare const g: <U>() => { [K in keyof U]: U[K] };

const h: typeof g = f;