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Properly distribute over unions in keyof for mapped types with as clause (microsoft#40837)
* Properly distribute over unions in keyof mapped types with as clause * Accept new baselines * Add regression test * Accept new baselines
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+126
-3
lines changed

5 files changed

+126
-3
lines changed

‎src/compiler/checker.ts

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -13436,8 +13436,9 @@ namespace ts {
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function getIndexTypeForMappedType(type: MappedType, noIndexSignatures: boolean | undefined) {
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const constraint = filterType(getConstraintTypeFromMappedType(type), t => !(noIndexSignatures && t.flags & (TypeFlags.Any | TypeFlags.String)));
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return type.declaration.nameType ?
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instantiateType(getTypeFromTypeNode(type.declaration.nameType), appendTypeMapping(type.mapper, getTypeParameterFromMappedType(type), constraint)) :
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const nameType = type.declaration.nameType && getTypeFromTypeNode(type.declaration.nameType);
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return nameType ?
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mapType(constraint, t => instantiateType(nameType, appendTypeMapping(type.mapper, getTypeParameterFromMappedType(type), t))) :
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constraint;
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}
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‎tests/baselines/reference/mappedTypeAsClauses.js

Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -42,11 +42,30 @@ interface Person {
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}
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type LazyPerson = Lazyify<Person>;
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// Repro from #40833
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type Example = {foo: string, bar: number};
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type PickByValueType<T, U> = {
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[K in keyof T as T[K] extends U ? K : never]: T[K]
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};
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type T1 = PickByValueType<Example, string>;
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const e1: T1 = {
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foo: "hello"
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};
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type T2 = keyof T1;
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const e2: T2 = "foo";
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//// [mappedTypeAsClauses.js]
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"use strict";
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// Mapped type 'as N' clauses
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var e1 = {
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foo: "hello"
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};
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var e2 = "foo";
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//// [mappedTypeAsClauses.d.ts]
@@ -105,3 +124,14 @@ interface Person {
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location?: string;
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}
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declare type LazyPerson = Lazyify<Person>;
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declare type Example = {
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foo: string;
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bar: number;
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};
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declare type PickByValueType<T, U> = {
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[K in keyof T as T[K] extends U ? K : never]: T[K];
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};
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declare type T1 = PickByValueType<Example, string>;
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declare const e1: T1;
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declare type T2 = keyof T1;
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declare const e2: T2;

‎tests/baselines/reference/mappedTypeAsClauses.symbols

Lines changed: 45 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -143,3 +143,48 @@ type LazyPerson = Lazyify<Person>;
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>Lazyify : Symbol(Lazyify, Decl(mappedTypeAsClauses.ts, 28, 34))
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>Person : Symbol(Person, Decl(mappedTypeAsClauses.ts, 34, 2))
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// Repro from #40833
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type Example = {foo: string, bar: number};
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>Example : Symbol(Example, Decl(mappedTypeAsClauses.ts, 42, 34))
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>foo : Symbol(foo, Decl(mappedTypeAsClauses.ts, 46, 16))
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>bar : Symbol(bar, Decl(mappedTypeAsClauses.ts, 46, 28))
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type PickByValueType<T, U> = {
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>PickByValueType : Symbol(PickByValueType, Decl(mappedTypeAsClauses.ts, 46, 42))
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>T : Symbol(T, Decl(mappedTypeAsClauses.ts, 48, 21))
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>U : Symbol(U, Decl(mappedTypeAsClauses.ts, 48, 23))
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[K in keyof T as T[K] extends U ? K : never]: T[K]
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>K : Symbol(K, Decl(mappedTypeAsClauses.ts, 49, 3))
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>T : Symbol(T, Decl(mappedTypeAsClauses.ts, 48, 21))
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>T : Symbol(T, Decl(mappedTypeAsClauses.ts, 48, 21))
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>K : Symbol(K, Decl(mappedTypeAsClauses.ts, 49, 3))
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>U : Symbol(U, Decl(mappedTypeAsClauses.ts, 48, 23))
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>K : Symbol(K, Decl(mappedTypeAsClauses.ts, 49, 3))
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>T : Symbol(T, Decl(mappedTypeAsClauses.ts, 48, 21))
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>K : Symbol(K, Decl(mappedTypeAsClauses.ts, 49, 3))
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};
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type T1 = PickByValueType<Example, string>;
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>T1 : Symbol(T1, Decl(mappedTypeAsClauses.ts, 50, 2))
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>PickByValueType : Symbol(PickByValueType, Decl(mappedTypeAsClauses.ts, 46, 42))
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>Example : Symbol(Example, Decl(mappedTypeAsClauses.ts, 42, 34))
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const e1: T1 = {
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>e1 : Symbol(e1, Decl(mappedTypeAsClauses.ts, 53, 5))
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>T1 : Symbol(T1, Decl(mappedTypeAsClauses.ts, 50, 2))
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foo: "hello"
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>foo : Symbol(foo, Decl(mappedTypeAsClauses.ts, 53, 16))
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};
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type T2 = keyof T1;
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>T2 : Symbol(T2, Decl(mappedTypeAsClauses.ts, 55, 2))
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>T1 : Symbol(T1, Decl(mappedTypeAsClauses.ts, 50, 2))
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const e2: T2 = "foo";
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>e2 : Symbol(e2, Decl(mappedTypeAsClauses.ts, 57, 5))
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>T2 : Symbol(T2, Decl(mappedTypeAsClauses.ts, 55, 2))
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‎tests/baselines/reference/mappedTypeAsClauses.types

Lines changed: 33 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -61,7 +61,7 @@ type TD1 = DoubleProp<{ a: string, b: number }>; // { a1: string, a2: string, b
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>b : number
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type TD2 = keyof TD1; // 'a1' | 'a2' | 'b1' | 'b2'
64-
>TD2 : "a1" | "b1" | "a2" | "b2"
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>TD2 : "a1" | "a2" | "b1" | "b2"
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type TD3<U> = keyof DoubleProp<U>; // `${keyof U & string}1` | `${keyof U & string}2`
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>TD3 : `${keyof U & string}1` | `${keyof U & string}2`
@@ -88,3 +88,35 @@ interface Person {
8888
type LazyPerson = Lazyify<Person>;
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>LazyPerson : Lazyify<Person>
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// Repro from #40833
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type Example = {foo: string, bar: number};
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>Example : Example
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>foo : string
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>bar : number
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type PickByValueType<T, U> = {
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>PickByValueType : PickByValueType<T, U>
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[K in keyof T as T[K] extends U ? K : never]: T[K]
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};
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type T1 = PickByValueType<Example, string>;
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>T1 : PickByValueType<Example, string>
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const e1: T1 = {
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>e1 : PickByValueType<Example, string>
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>{ foo: "hello"} : { foo: string; }
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foo: "hello"
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>foo : string
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>"hello" : "hello"
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};
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type T2 = keyof T1;
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>T2 : "foo"
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const e2: T2 = "foo";
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>e2 : "foo"
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>"foo" : "foo"
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‎tests/cases/conformance/types/mapped/mappedTypeAsClauses.ts

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -44,3 +44,18 @@ interface Person {
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}
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type LazyPerson = Lazyify<Person>;
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// Repro from #40833
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50+
type Example = {foo: string, bar: number};
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52+
type PickByValueType<T, U> = {
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[K in keyof T as T[K] extends U ? K : never]: T[K]
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};
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type T1 = PickByValueType<Example, string>;
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const e1: T1 = {
58+
foo: "hello"
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};
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type T2 = keyof T1;
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const e2: T2 = "foo";

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