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weswighamweswigham
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Consider inferences between mapped type templates lower priority
1 parent 9eab334 commit 99110e9

5 files changed

+191
-2
lines changed

‎src/compiler/checker.ts

+4-2
Original file line numberDiff line numberDiff line change
@@ -21718,12 +21718,14 @@ namespace ts {
2171821718
}
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function inferFromIndexTypes(source: Type, target: Type) {
21721+
// Inferences across mapped type index signatures are pretty much the same a inferences to homomorphic variables
21722+
const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) ? InferencePriority.HomomorphicMappedType : 0;
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const targetStringIndexType = getIndexTypeOfType(target, IndexKind.String);
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if (targetStringIndexType) {
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const sourceIndexType = getIndexTypeOfType(source, IndexKind.String) ||
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getImplicitIndexTypeOfType(source, IndexKind.String);
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if (sourceIndexType) {
21726-
inferFromTypes(sourceIndexType, targetStringIndexType);
21728+
inferWithPriority(sourceIndexType, targetStringIndexType, priority);
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}
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}
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const targetNumberIndexType = getIndexTypeOfType(target, IndexKind.Number);
@@ -21732,7 +21734,7 @@ namespace ts {
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getIndexTypeOfType(source, IndexKind.String) ||
2173321735
getImplicitIndexTypeOfType(source, IndexKind.Number);
2173421736
if (sourceIndexType) {
21735-
inferFromTypes(sourceIndexType, targetNumberIndexType);
21737+
inferWithPriority(sourceIndexType, targetNumberIndexType, priority);
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}
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}
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}

‎tests/baselines/reference/localTypeParameterInferencePriority.js

+58
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,58 @@
1+
//// [localTypeParameterInferencePriority.ts]
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export type UnrollOnHover<O extends object> = O extends object ?
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{ [K in keyof O]: O[K]; } :
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never;
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6+
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export type Schema = Record<string, unknown>;
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class Table<S extends Schema> {
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__schema!: S;
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// Removing this line, removes the error
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getRows<C extends keyof S>(): Array<UnrollOnHover<Pick<S, C>>> {
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return null!
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}
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}
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class ColumnSelectViewImp<S extends Schema> extends Table<S> { }
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const ColumnSelectView1: new <S extends Schema>() => Table<UnrollOnHover<S>> = ColumnSelectViewImp;
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const ColumnSelectView2: new <S extends Schema>() => Table<UnrollOnHover<S>> = Table;
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//// [localTypeParameterInferencePriority.js]
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"use strict";
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var __extends = (this && this.__extends) || (function () {
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var extendStatics = function (d, b) {
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extendStatics = Object.setPrototypeOf ||
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({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
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function (d, b) { for (var p in b) if (Object.prototype.hasOwnProperty.call(b, p)) d[p] = b[p]; };
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return extendStatics(d, b);
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};
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return function (d, b) {
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if (typeof b !== "function" && b !== null)
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throw new TypeError("Class extends value " + String(b) + " is not a constructor or null");
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extendStatics(d, b);
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function __() { this.constructor = d; }
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d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
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};
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})();
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exports.__esModule = true;
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var Table = /** @class */ (function () {
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function Table() {
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}
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// Removing this line, removes the error
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Table.prototype.getRows = function () {
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return null;
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};
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return Table;
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}());
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var ColumnSelectViewImp = /** @class */ (function (_super) {
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__extends(ColumnSelectViewImp, _super);
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function ColumnSelectViewImp() {
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return _super !== null && _super.apply(this, arguments) || this;
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}
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return ColumnSelectViewImp;
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}(Table));
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var ColumnSelectView1 = ColumnSelectViewImp;
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var ColumnSelectView2 = Table;

‎tests/baselines/reference/localTypeParameterInferencePriority.symbols

+69
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,69 @@
1+
=== tests/cases/compiler/localTypeParameterInferencePriority.ts ===
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export type UnrollOnHover<O extends object> = O extends object ?
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>UnrollOnHover : Symbol(UnrollOnHover, Decl(localTypeParameterInferencePriority.ts, 0, 0))
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>O : Symbol(O, Decl(localTypeParameterInferencePriority.ts, 0, 26))
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>O : Symbol(O, Decl(localTypeParameterInferencePriority.ts, 0, 26))
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{ [K in keyof O]: O[K]; } :
8+
>K : Symbol(K, Decl(localTypeParameterInferencePriority.ts, 1, 7))
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>O : Symbol(O, Decl(localTypeParameterInferencePriority.ts, 0, 26))
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>O : Symbol(O, Decl(localTypeParameterInferencePriority.ts, 0, 26))
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>K : Symbol(K, Decl(localTypeParameterInferencePriority.ts, 1, 7))
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never;
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15+
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export type Schema = Record<string, unknown>;
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>Schema : Symbol(Schema, Decl(localTypeParameterInferencePriority.ts, 2, 10))
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>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
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class Table<S extends Schema> {
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>Table : Symbol(Table, Decl(localTypeParameterInferencePriority.ts, 5, 45))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 6, 12))
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>Schema : Symbol(Schema, Decl(localTypeParameterInferencePriority.ts, 2, 10))
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__schema!: S;
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>__schema : Symbol(Table.__schema, Decl(localTypeParameterInferencePriority.ts, 6, 32))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 6, 12))
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// Removing this line, removes the error
30+
getRows<C extends keyof S>(): Array<UnrollOnHover<Pick<S, C>>> {
31+
>getRows : Symbol(Table.getRows, Decl(localTypeParameterInferencePriority.ts, 7, 17))
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>C : Symbol(C, Decl(localTypeParameterInferencePriority.ts, 10, 12))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 6, 12))
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>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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>UnrollOnHover : Symbol(UnrollOnHover, Decl(localTypeParameterInferencePriority.ts, 0, 0))
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>Pick : Symbol(Pick, Decl(lib.es5.d.ts, --, --))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 6, 12))
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>C : Symbol(C, Decl(localTypeParameterInferencePriority.ts, 10, 12))
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40+
return null!
41+
}
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}
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class ColumnSelectViewImp<S extends Schema> extends Table<S> { }
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>ColumnSelectViewImp : Symbol(ColumnSelectViewImp, Decl(localTypeParameterInferencePriority.ts, 13, 1))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 15, 26))
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>Schema : Symbol(Schema, Decl(localTypeParameterInferencePriority.ts, 2, 10))
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>Table : Symbol(Table, Decl(localTypeParameterInferencePriority.ts, 5, 45))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 15, 26))
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const ColumnSelectView1: new <S extends Schema>() => Table<UnrollOnHover<S>> = ColumnSelectViewImp;
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>ColumnSelectView1 : Symbol(ColumnSelectView1, Decl(localTypeParameterInferencePriority.ts, 18, 5))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 18, 30))
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>Schema : Symbol(Schema, Decl(localTypeParameterInferencePriority.ts, 2, 10))
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>Table : Symbol(Table, Decl(localTypeParameterInferencePriority.ts, 5, 45))
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>UnrollOnHover : Symbol(UnrollOnHover, Decl(localTypeParameterInferencePriority.ts, 0, 0))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 18, 30))
59+
>ColumnSelectViewImp : Symbol(ColumnSelectViewImp, Decl(localTypeParameterInferencePriority.ts, 13, 1))
60+
61+
const ColumnSelectView2: new <S extends Schema>() => Table<UnrollOnHover<S>> = Table;
62+
>ColumnSelectView2 : Symbol(ColumnSelectView2, Decl(localTypeParameterInferencePriority.ts, 19, 5))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 19, 30))
64+
>Schema : Symbol(Schema, Decl(localTypeParameterInferencePriority.ts, 2, 10))
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>Table : Symbol(Table, Decl(localTypeParameterInferencePriority.ts, 5, 45))
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>UnrollOnHover : Symbol(UnrollOnHover, Decl(localTypeParameterInferencePriority.ts, 0, 0))
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>S : Symbol(S, Decl(localTypeParameterInferencePriority.ts, 19, 30))
68+
>Table : Symbol(Table, Decl(localTypeParameterInferencePriority.ts, 5, 45))
69+

‎tests/baselines/reference/localTypeParameterInferencePriority.types

+40
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,40 @@
1+
=== tests/cases/compiler/localTypeParameterInferencePriority.ts ===
2+
export type UnrollOnHover<O extends object> = O extends object ?
3+
>UnrollOnHover : UnrollOnHover<O>
4+
5+
{ [K in keyof O]: O[K]; } :
6+
never;
7+
8+
9+
export type Schema = Record<string, unknown>;
10+
>Schema : Schema
11+
12+
class Table<S extends Schema> {
13+
>Table : Table<S>
14+
15+
__schema!: S;
16+
>__schema : S
17+
18+
// Removing this line, removes the error
19+
getRows<C extends keyof S>(): Array<UnrollOnHover<Pick<S, C>>> {
20+
>getRows : <C extends keyof S>() => Array<UnrollOnHover<Pick<S, C>>>
21+
22+
return null!
23+
>null! : null
24+
>null : null
25+
}
26+
}
27+
28+
class ColumnSelectViewImp<S extends Schema> extends Table<S> { }
29+
>ColumnSelectViewImp : ColumnSelectViewImp<S>
30+
>Table : Table<S>
31+
32+
33+
const ColumnSelectView1: new <S extends Schema>() => Table<UnrollOnHover<S>> = ColumnSelectViewImp;
34+
>ColumnSelectView1 : new <S extends Schema>() => Table<UnrollOnHover<S>>
35+
>ColumnSelectViewImp : typeof ColumnSelectViewImp
36+
37+
const ColumnSelectView2: new <S extends Schema>() => Table<UnrollOnHover<S>> = Table;
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>ColumnSelectView2 : new <S extends Schema>() => Table<UnrollOnHover<S>>
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>Table : typeof Table
40+

‎tests/cases/compiler/localTypeParameterInferencePriority.ts

+20
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
export type UnrollOnHover<O extends object> = O extends object ?
2+
{ [K in keyof O]: O[K]; } :
3+
never;
4+
5+
6+
export type Schema = Record<string, unknown>;
7+
class Table<S extends Schema> {
8+
__schema!: S;
9+
10+
// Removing this line, removes the error
11+
getRows<C extends keyof S>(): Array<UnrollOnHover<Pick<S, C>>> {
12+
return null!
13+
}
14+
}
15+
16+
class ColumnSelectViewImp<S extends Schema> extends Table<S> { }
17+
18+
19+
const ColumnSelectView1: new <S extends Schema>() => Table<UnrollOnHover<S>> = ColumnSelectViewImp;
20+
const ColumnSelectView2: new <S extends Schema>() => Table<UnrollOnHover<S>> = Table;

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