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Only widen return types of function expressions in the absence of a contextual signature.

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This commit is contained in:
Daniel Rosenwasser
2020-08-28 23:56:43 +00:00
parent 44c5d87184
commit 8f45d2367a
1 changed files with 11 additions and 7 deletions
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src/compiler/checker.ts
+11 -7
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@@ -28295,14 +28295,16 @@ namespace ts {
returnType = getUnionType(types, UnionReduction.Subtype);
}
const contextualSignature = getContextualSignatureForFunctionLikeDeclaration(func);
if (returnType || yieldType || nextType) {
if (yieldType) reportErrorsFromWidening(func, yieldType, WideningKind.GeneratorYield);
if (returnType) reportErrorsFromWidening(func, returnType, WideningKind.FunctionReturn);
if (nextType) reportErrorsFromWidening(func, nextType, WideningKind.GeneratorNext);
if (!contextualSignature) {
if (yieldType) reportErrorsFromWidening(func, yieldType, WideningKind.GeneratorYield);
if (returnType) reportErrorsFromWidening(func, returnType, WideningKind.FunctionReturn);
if (nextType) reportErrorsFromWidening(func, nextType, WideningKind.GeneratorNext);
}
if (returnType && isUnitType(returnType) ||
yieldType && isUnitType(yieldType) ||
nextType && isUnitType(nextType)) {
const contextualSignature = getContextualSignatureForFunctionLikeDeclaration(func);
const contextualType = !contextualSignature ? undefined :
contextualSignature === getSignatureFromDeclaration(func) ? isGenerator ? undefined : returnType :
instantiateContextualType(getReturnTypeOfSignature(contextualSignature), func);
@@ -28316,9 +28318,11 @@ namespace ts {
}
}
if (yieldType) yieldType = getWidenedType(yieldType);
if (returnType) returnType = getWidenedType(returnType);
if (nextType) nextType = getWidenedType(nextType);
if (!contextualSignature) {
if (yieldType) yieldType = getWidenedType(yieldType);
if (returnType) returnType = getWidenedType(returnType);
if (nextType) nextType = getWidenedType(nextType);
}
}
if (isGenerator) {