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Handle propagating substitution types to retain constraints on positions through instantiation
1 parent 88623ad commit aa2709f

10 files changed

+195
-37
lines changed

‎src/compiler/checker.ts

Lines changed: 57 additions & 33 deletions
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‎src/compiler/types.ts

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4064,7 +4064,7 @@ namespace ts {
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// Thus, if Foo has a 'string' constraint on its type parameter, T will satisfy it. Substitution
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// types disappear upon instantiation (just like type parameters).
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export interface SubstitutionType extends InstantiableType {
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typeVariable: TypeVariable; // Target type variable
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typeVariable: Type; // Target type variable
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substitute: Type; // Type to substitute for type parameter
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negatedTypes?: Type[]; // Types proven that this type variables _doesn't_ extend
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}
@@ -4153,6 +4153,7 @@ namespace ts {
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InferUnionTypes = 1 << 0, // Infer union types for disjoint candidates (otherwise unknownType)
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NoDefault = 1 << 1, // Infer unknownType for no inferences (otherwise anyType or emptyObjectType)
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AnyDefault = 1 << 2, // Infer anyType for no inferences (otherwise emptyObjectType)
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SkipConstraintCheck = 1 << 3, // Skip checking weather the inference is assignable to the constraint (otherwise is replaced with constraint)
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}
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/**

‎tests/baselines/reference/api/tsserverlibrary.d.ts

Lines changed: 1 addition & 1 deletion
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@@ -2300,7 +2300,7 @@ declare namespace ts {
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resolvedFalseType?: Type;
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}
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interface SubstitutionType extends InstantiableType {
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typeVariable: TypeVariable;
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typeVariable: Type;
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substitute: Type;
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negatedTypes?: Type[];
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}

‎tests/baselines/reference/api/typescript.d.ts

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2300,7 +2300,7 @@ declare namespace ts {
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resolvedFalseType?: Type;
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}
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interface SubstitutionType extends InstantiableType {
2303-
typeVariable: TypeVariable;
2303+
typeVariable: Type;
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substitute: Type;
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negatedTypes?: Type[];
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}

‎tests/baselines/reference/conditionalTypeGenericAssignability.errors.txt

Lines changed: 19 additions & 0 deletions
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@@ -0,0 +1,19 @@
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tests/cases/compiler/conditionalTypeGenericAssignability.ts(3,5): error TS2322: Type '0' is not assignable to type 'Extract<keyof T, string>'.
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tests/cases/compiler/conditionalTypeGenericAssignability.ts(7,5): error TS2322: Type '"foo"' is not assignable to type 'Exclude<keyof T, string>'.
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==== tests/cases/compiler/conditionalTypeGenericAssignability.ts (2 errors) ====
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function f1<T extends { foo: unknown; 0: unknown }>(_a: T, b: Extract<keyof T, string>) {
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b = "foo"; // succeeds
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b = 0; // errors
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~
10+
!!! error TS2322: Type '0' is not assignable to type 'Extract<keyof T, string>'.
11+
}
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function f2<T extends { foo: unknown; 0: unknown }>(_a: T, b: Exclude<keyof T, string>) {
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b = "foo"; // errors
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~
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!!! error TS2322: Type '"foo"' is not assignable to type 'Exclude<keyof T, string>'.
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b = 0; // succeeds
18+
}
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‎tests/baselines/reference/conditionalTypeGenericAssignability.js

Lines changed: 22 additions & 0 deletions
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@@ -0,0 +1,22 @@
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//// [conditionalTypeGenericAssignability.ts]
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function f1<T extends { foo: unknown; 0: unknown }>(_a: T, b: Extract<keyof T, string>) {
3+
b = "foo"; // succeeds
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b = 0; // errors
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}
6+
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function f2<T extends { foo: unknown; 0: unknown }>(_a: T, b: Exclude<keyof T, string>) {
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b = "foo"; // errors
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b = 0; // succeeds
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}
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//// [conditionalTypeGenericAssignability.js]
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"use strict";
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function f1(_a, b) {
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b = "foo"; // succeeds
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b = 0; // errors
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}
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function f2(_a, b) {
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b = "foo"; // errors
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b = 0; // succeeds
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}

‎tests/baselines/reference/conditionalTypeGenericAssignability.symbols

Lines changed: 37 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,37 @@
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=== tests/cases/compiler/conditionalTypeGenericAssignability.ts ===
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function f1<T extends { foo: unknown; 0: unknown }>(_a: T, b: Extract<keyof T, string>) {
3+
>f1 : Symbol(f1, Decl(conditionalTypeGenericAssignability.ts, 0, 0))
4+
>T : Symbol(T, Decl(conditionalTypeGenericAssignability.ts, 0, 12))
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>foo : Symbol(foo, Decl(conditionalTypeGenericAssignability.ts, 0, 23))
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>0 : Symbol(0, Decl(conditionalTypeGenericAssignability.ts, 0, 37))
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>_a : Symbol(_a, Decl(conditionalTypeGenericAssignability.ts, 0, 52))
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>T : Symbol(T, Decl(conditionalTypeGenericAssignability.ts, 0, 12))
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>b : Symbol(b, Decl(conditionalTypeGenericAssignability.ts, 0, 58))
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>Extract : Symbol(Extract, Decl(lib.es5.d.ts, --, --))
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>T : Symbol(T, Decl(conditionalTypeGenericAssignability.ts, 0, 12))
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b = "foo"; // succeeds
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>b : Symbol(b, Decl(conditionalTypeGenericAssignability.ts, 0, 58))
15+
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b = 0; // errors
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>b : Symbol(b, Decl(conditionalTypeGenericAssignability.ts, 0, 58))
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}
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function f2<T extends { foo: unknown; 0: unknown }>(_a: T, b: Exclude<keyof T, string>) {
21+
>f2 : Symbol(f2, Decl(conditionalTypeGenericAssignability.ts, 3, 1))
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>T : Symbol(T, Decl(conditionalTypeGenericAssignability.ts, 5, 12))
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>foo : Symbol(foo, Decl(conditionalTypeGenericAssignability.ts, 5, 23))
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>0 : Symbol(0, Decl(conditionalTypeGenericAssignability.ts, 5, 37))
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>_a : Symbol(_a, Decl(conditionalTypeGenericAssignability.ts, 5, 52))
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>T : Symbol(T, Decl(conditionalTypeGenericAssignability.ts, 5, 12))
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>b : Symbol(b, Decl(conditionalTypeGenericAssignability.ts, 5, 58))
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>Exclude : Symbol(Exclude, Decl(lib.es5.d.ts, --, --))
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>T : Symbol(T, Decl(conditionalTypeGenericAssignability.ts, 5, 12))
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31+
b = "foo"; // errors
32+
>b : Symbol(b, Decl(conditionalTypeGenericAssignability.ts, 5, 58))
33+
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b = 0; // succeeds
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>b : Symbol(b, Decl(conditionalTypeGenericAssignability.ts, 5, 58))
36+
}
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‎tests/baselines/reference/conditionalTypeGenericAssignability.types

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@@ -0,0 +1,45 @@
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=== tests/cases/compiler/conditionalTypeGenericAssignability.ts ===
2+
function f1<T extends { foo: unknown; 0: unknown }>(_a: T, b: Extract<keyof T, string>) {
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>f1 : <T extends { foo: unknown; 0: unknown; }>(_a: T, b: Extract<keyof T, string>) => void
4+
>T : T
5+
>foo : unknown
6+
>0 : unknown
7+
>_a : T
8+
>T : T
9+
>b : Extract<keyof T, string>
10+
>Extract : Extract<T, U>
11+
>T : T
12+
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b = "foo"; // succeeds
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>b = "foo" : "foo"
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>b : Extract<keyof T, string>
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>"foo" : "foo"
17+
18+
b = 0; // errors
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>b = 0 : 0
20+
>b : Extract<keyof T, string>
21+
>0 : 0
22+
}
23+
24+
function f2<T extends { foo: unknown; 0: unknown }>(_a: T, b: Exclude<keyof T, string>) {
25+
>f2 : <T extends { foo: unknown; 0: unknown; }>(_a: T, b: Exclude<keyof T, string>) => void
26+
>T : T
27+
>foo : unknown
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>0 : unknown
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>_a : T
30+
>T : T
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>b : Exclude<keyof T, string>
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>Exclude : Exclude<T, U>
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>T : T
34+
35+
b = "foo"; // errors
36+
>b = "foo" : "foo"
37+
>b : Exclude<keyof T, string>
38+
>"foo" : "foo"
39+
40+
b = 0; // succeeds
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>b = 0 : 0
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>b : Exclude<keyof T, string>
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>0 : 0
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}
45+

‎tests/baselines/reference/inferTypes1.types

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -320,7 +320,7 @@ type T61<T> = infer A extends infer B ? infer C : infer D; // Error
320320
>D : D
321321

322322
type T62<T> = U extends (infer U)[] ? U : U; // Error
323-
>T62 : any
323+
>T62 : {} | any
324324
>T : T
325325
>U : No type information available!
326326
>U : U

‎tests/cases/compiler/conditionalTypeGenericAssignability.ts

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@@ -0,0 +1,10 @@
1+
// @strict: true
2+
function f1<T extends { foo: unknown; 0: unknown }>(_a: T, b: Extract<keyof T, string>) {
3+
b = "foo"; // succeeds
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b = 0; // errors
5+
}
6+
7+
function f2<T extends { foo: unknown; 0: unknown }>(_a: T, b: Exclude<keyof T, string>) {
8+
b = "foo"; // errors
9+
b = 0; // succeeds
10+
}

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