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No contextual typing from return types for boolean literals (microsoft#48380)
* No contextual typing from return types for boolean literals * Accept new baselines * Add regression tests
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7 files changed

+230
-11
lines changed

7 files changed

+230
-11
lines changed

‎src/compiler/checker.ts‎

Lines changed: 7 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -26902,9 +26902,14 @@ namespace ts {
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return instantiateInstantiableTypes(contextualType, inferenceContext.nonFixingMapper);
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}
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// For other purposes (e.g. determining whether to produce literal types) we only
26905-
// incorporate inferences made from the return type in a function call.
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// incorporate inferences made from the return type in a function call. We remove
26906+
// the 'boolean' type from the contextual type such that contextually typed boolean
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// literals actually end up widening to 'boolean' (see #48363).
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if (inferenceContext.returnMapper) {
26907-
return instantiateInstantiableTypes(contextualType, inferenceContext.returnMapper);
26909+
const type = instantiateInstantiableTypes(contextualType, inferenceContext.returnMapper);
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return type.flags & TypeFlags.Union && containsType((type as UnionType).types, regularFalseType) && containsType((type as UnionType).types, regularTrueType) ?
26911+
filterType(type, t => t !== regularFalseType && t !== regularTrueType) :
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type;
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}
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}
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}

‎tests/baselines/reference/contextuallyTypedBooleanLiterals.js‎

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@@ -0,0 +1,55 @@
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//// [contextuallyTypedBooleanLiterals.ts]
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// Repro from #48363
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type Box<T> = {
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get: () => T,
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set: (value: T) => void
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}
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declare function box<T>(value: T): Box<T>;
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const bn1 = box(0); // Box<number>
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const bn2: Box<number> = box(0); // Ok
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const bb1 = box(false); // Box<boolean>
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const bb2: Box<boolean> = box(false); // Error, box<false> not assignable to Box<boolean>
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// Repro from #48150
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interface Observable<T>
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{
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(): T;
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(value: T): any;
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}
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declare function observable<T>(value: T): Observable<T>;
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const x: Observable<boolean> = observable(false);
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//// [contextuallyTypedBooleanLiterals.js]
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"use strict";
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// Repro from #48363
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var bn1 = box(0); // Box<number>
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var bn2 = box(0); // Ok
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var bb1 = box(false); // Box<boolean>
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var bb2 = box(false); // Error, box<false> not assignable to Box<boolean>
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var x = observable(false);
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//// [contextuallyTypedBooleanLiterals.d.ts]
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declare type Box<T> = {
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get: () => T;
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set: (value: T) => void;
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};
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declare function box<T>(value: T): Box<T>;
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declare const bn1: Box<number>;
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declare const bn2: Box<number>;
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declare const bb1: Box<boolean>;
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declare const bb2: Box<boolean>;
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interface Observable<T> {
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(): T;
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(value: T): any;
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}
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declare function observable<T>(value: T): Observable<T>;
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declare const x: Observable<boolean>;

‎tests/baselines/reference/contextuallyTypedBooleanLiterals.symbols‎

Lines changed: 70 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,70 @@
1+
=== tests/cases/compiler/contextuallyTypedBooleanLiterals.ts ===
2+
// Repro from #48363
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type Box<T> = {
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>Box : Symbol(Box, Decl(contextuallyTypedBooleanLiterals.ts, 0, 0))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 2, 9))
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get: () => T,
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>get : Symbol(get, Decl(contextuallyTypedBooleanLiterals.ts, 2, 15))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 2, 9))
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set: (value: T) => void
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>set : Symbol(set, Decl(contextuallyTypedBooleanLiterals.ts, 3, 17))
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>value : Symbol(value, Decl(contextuallyTypedBooleanLiterals.ts, 4, 10))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 2, 9))
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}
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declare function box<T>(value: T): Box<T>;
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>box : Symbol(box, Decl(contextuallyTypedBooleanLiterals.ts, 5, 1))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 7, 21))
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>value : Symbol(value, Decl(contextuallyTypedBooleanLiterals.ts, 7, 24))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 7, 21))
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>Box : Symbol(Box, Decl(contextuallyTypedBooleanLiterals.ts, 0, 0))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 7, 21))
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const bn1 = box(0); // Box<number>
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>bn1 : Symbol(bn1, Decl(contextuallyTypedBooleanLiterals.ts, 9, 5))
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>box : Symbol(box, Decl(contextuallyTypedBooleanLiterals.ts, 5, 1))
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const bn2: Box<number> = box(0); // Ok
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>bn2 : Symbol(bn2, Decl(contextuallyTypedBooleanLiterals.ts, 10, 5))
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>Box : Symbol(Box, Decl(contextuallyTypedBooleanLiterals.ts, 0, 0))
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>box : Symbol(box, Decl(contextuallyTypedBooleanLiterals.ts, 5, 1))
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const bb1 = box(false); // Box<boolean>
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>bb1 : Symbol(bb1, Decl(contextuallyTypedBooleanLiterals.ts, 12, 5))
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>box : Symbol(box, Decl(contextuallyTypedBooleanLiterals.ts, 5, 1))
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const bb2: Box<boolean> = box(false); // Error, box<false> not assignable to Box<boolean>
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>bb2 : Symbol(bb2, Decl(contextuallyTypedBooleanLiterals.ts, 13, 5))
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>Box : Symbol(Box, Decl(contextuallyTypedBooleanLiterals.ts, 0, 0))
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>box : Symbol(box, Decl(contextuallyTypedBooleanLiterals.ts, 5, 1))
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// Repro from #48150
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interface Observable<T>
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>Observable : Symbol(Observable, Decl(contextuallyTypedBooleanLiterals.ts, 13, 37))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 17, 21))
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{
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(): T;
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 17, 21))
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(value: T): any;
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>value : Symbol(value, Decl(contextuallyTypedBooleanLiterals.ts, 20, 3))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 17, 21))
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}
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declare function observable<T>(value: T): Observable<T>;
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>observable : Symbol(observable, Decl(contextuallyTypedBooleanLiterals.ts, 21, 1))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 23, 28))
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>value : Symbol(value, Decl(contextuallyTypedBooleanLiterals.ts, 23, 31))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 23, 28))
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>Observable : Symbol(Observable, Decl(contextuallyTypedBooleanLiterals.ts, 13, 37))
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>T : Symbol(T, Decl(contextuallyTypedBooleanLiterals.ts, 23, 28))
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const x: Observable<boolean> = observable(false);
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>x : Symbol(x, Decl(contextuallyTypedBooleanLiterals.ts, 25, 5))
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>Observable : Symbol(Observable, Decl(contextuallyTypedBooleanLiterals.ts, 13, 37))
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>observable : Symbol(observable, Decl(contextuallyTypedBooleanLiterals.ts, 21, 1))
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‎tests/baselines/reference/contextuallyTypedBooleanLiterals.types‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,61 @@
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=== tests/cases/compiler/contextuallyTypedBooleanLiterals.ts ===
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// Repro from #48363
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4+
type Box<T> = {
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>Box : Box<T>
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get: () => T,
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>get : () => T
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set: (value: T) => void
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>set : (value: T) => void
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>value : T
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}
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declare function box<T>(value: T): Box<T>;
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>box : <T>(value: T) => Box<T>
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>value : T
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const bn1 = box(0); // Box<number>
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>bn1 : Box<number>
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>box(0) : Box<number>
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>box : <T>(value: T) => Box<T>
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>0 : 0
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const bn2: Box<number> = box(0); // Ok
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>bn2 : Box<number>
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>box(0) : Box<number>
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>box : <T>(value: T) => Box<T>
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>0 : 0
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const bb1 = box(false); // Box<boolean>
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>bb1 : Box<boolean>
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>box(false) : Box<boolean>
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>box : <T>(value: T) => Box<T>
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>false : false
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const bb2: Box<boolean> = box(false); // Error, box<false> not assignable to Box<boolean>
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>bb2 : Box<boolean>
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>box(false) : Box<boolean>
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>box : <T>(value: T) => Box<T>
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>false : false
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// Repro from #48150
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interface Observable<T>
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{
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(): T;
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(value: T): any;
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>value : T
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}
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declare function observable<T>(value: T): Observable<T>;
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>observable : <T>(value: T) => Observable<T>
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>value : T
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const x: Observable<boolean> = observable(false);
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>x : Observable<boolean>
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>observable(false) : Observable<boolean>
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>observable : <T>(value: T) => Observable<T>
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>false : false
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‎tests/baselines/reference/inferFromGenericFunctionReturnTypes3.errors.txt‎

Lines changed: 1 addition & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,12 @@
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tests/cases/compiler/inferFromGenericFunctionReturnTypes3.ts(28,30): error TS2345: Argument of type 'string' is not assignable to parameter of type '"bar"'.
2-
tests/cases/compiler/inferFromGenericFunctionReturnTypes3.ts(175,47): error TS2322: Type 'boolean' is not assignable to type 'true'.
32
tests/cases/compiler/inferFromGenericFunctionReturnTypes3.ts(180,26): error TS2322: Type '{ state: State.A; }[] | { state: State.B; }[]' is not assignable to type '{ state: State.A; }[]'.
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Type '{ state: State.B; }[]' is not assignable to type '{ state: State.A; }[]'.
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Type '{ state: State.B; }' is not assignable to type '{ state: State.A; }'.
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Types of property 'state' are incompatible.
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Type 'State.B' is not assignable to type 'State.A'.
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98

10-
==== tests/cases/compiler/inferFromGenericFunctionReturnTypes3.ts (3 errors) ====
9+
==== tests/cases/compiler/inferFromGenericFunctionReturnTypes3.ts (2 errors) ====
1110
// Repros from #5487
1211

1312
function truePromise(): Promise<true> {
@@ -185,9 +184,6 @@ tests/cases/compiler/inferFromGenericFunctionReturnTypes3.ts(180,26): error TS23
185184

186185
declare function foldLeft<U>(z: U, f: (acc: U, t: boolean) => U): U;
187186
let res: boolean = foldLeft(true, (acc, t) => acc && t); // Error
188-
~~~~~~~~
189-
!!! error TS2322: Type 'boolean' is not assignable to type 'true'.
190-
!!! related TS6502 tests/cases/compiler/inferFromGenericFunctionReturnTypes3.ts:174:39: The expected type comes from the return type of this signature.
191187

192188
enum State { A, B }
193189
type Foo = { state: State }

‎tests/baselines/reference/inferFromGenericFunctionReturnTypes3.types‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -461,14 +461,14 @@ declare function foldLeft<U>(z: U, f: (acc: U, t: boolean) => U): U;
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462462
let res: boolean = foldLeft(true, (acc, t) => acc && t); // Error
463463
>res : boolean
464-
>foldLeft(true, (acc, t) => acc && t) : true
464+
>foldLeft(true, (acc, t) => acc && t) : boolean
465465
>foldLeft : <U>(z: U, f: (acc: U, t: boolean) => U) => U
466466
>true : true
467-
>(acc, t) => acc && t : (acc: true, t: boolean) => boolean
468-
>acc : true
467+
>(acc, t) => acc && t : (acc: boolean, t: boolean) => boolean
468+
>acc : boolean
469469
>t : boolean
470470
>acc && t : boolean
471-
>acc : true
471+
>acc : boolean
472472
>t : boolean
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474474
enum State { A, B }

‎tests/cases/compiler/contextuallyTypedBooleanLiterals.ts‎

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// @strict: true
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// @declaration: true
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// @strict: true
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// @declaration: true
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// Repro from #48363
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type Box<T> = {
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get: () => T,
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set: (value: T) => void
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}
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declare function box<T>(value: T): Box<T>;
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const bn1 = box(0); // Box<number>
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const bn2: Box<number> = box(0); // Ok
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const bb1 = box(false); // Box<boolean>
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const bb2: Box<boolean> = box(false); // Error, box<false> not assignable to Box<boolean>
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// Repro from #48150
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interface Observable<T>
25+
{
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(): T;
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(value: T): any;
28+
}
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declare function observable<T>(value: T): Observable<T>;
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const x: Observable<boolean> = observable(false);

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