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Handle the mapping between Array and ReadonlyArray in isTypeDerivedFrom

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This commit is contained in:
Wesley Wigham
2020-09-16 13:31:13 -07:00
parent a5babe1c8f
commit 081f98232b
5 changed files with 71 additions and 1 deletions
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2
src/compiler/checker.ts
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@@ -15349,7 +15349,7 @@ namespace ts {
source.flags & TypeFlags.InstantiableNonPrimitive ? isTypeDerivedFrom(getBaseConstraintOfType(source) || unknownType, target) :
target === globalObjectType ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) :
target === globalFunctionType ? !!(source.flags & TypeFlags.Object) && isFunctionObjectType(source as ObjectType) :
hasBaseType(source, getTargetType(target));
hasBaseType(source, getTargetType(target)) || (isArrayType(target) && !isReadonlyArrayType(target) && isTypeDerivedFrom(source, globalReadonlyArrayType));
}
/**

21
tests/baselines/reference/instanceofNarrowReadonlyArray.js Normal file
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@@ -0,0 +1,21 @@
//// [instanceofNarrowReadonlyArray.ts]
// @strict
function narrow(x: readonly number[] | number): readonly number[] {
if (x instanceof Array) {
return x;
} else {
return [x];
}
}
//// [instanceofNarrowReadonlyArray.js]
// @strict
function narrow(x) {
if (x instanceof Array) {
return x;
}
else {
return [x];
}
}

19
tests/baselines/reference/instanceofNarrowReadonlyArray.symbols Normal file
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@@ -0,0 +1,19 @@
=== tests/cases/compiler/instanceofNarrowReadonlyArray.ts ===
// @strict
function narrow(x: readonly number[] | number): readonly number[] {
>narrow : Symbol(narrow, Decl(instanceofNarrowReadonlyArray.ts, 0, 0))
>x : Symbol(x, Decl(instanceofNarrowReadonlyArray.ts, 2, 16))
if (x instanceof Array) {
>x : Symbol(x, Decl(instanceofNarrowReadonlyArray.ts, 2, 16))
>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
return x;
>x : Symbol(x, Decl(instanceofNarrowReadonlyArray.ts, 2, 16))
} else {
return [x];
>x : Symbol(x, Decl(instanceofNarrowReadonlyArray.ts, 2, 16))
}
}

21
tests/baselines/reference/instanceofNarrowReadonlyArray.types Normal file
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@@ -0,0 +1,21 @@
=== tests/cases/compiler/instanceofNarrowReadonlyArray.ts ===
// @strict
function narrow(x: readonly number[] | number): readonly number[] {
>narrow : (x: readonly number[] | number) => readonly number[]
>x : number | readonly number[]
if (x instanceof Array) {
>x instanceof Array : boolean
>x : number | readonly number[]
>Array : ArrayConstructor
return x;
>x : readonly number[]
} else {
return [x];
>[x] : number[]
>x : number
}
}

9
tests/cases/compiler/instanceofNarrowReadonlyArray.ts Normal file
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@@ -0,0 +1,9 @@
// @strict
function narrow(x: readonly number[] | number): readonly number[] {
if (x instanceof Array) {
return x;
} else {
return [x];
}
}