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Create returnOnlySignature only when inferences will possibly be made (#35173)

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* Create returnOnlySignature only when inferences will possibly be made

* Add regression test

* Accept new baselines
This commit is contained in:
Anders Hejlsberg
2019-11-25 15:05:53 -08:00
committed by GitHub
parent 0c17476d09
commit 0c2c58c42f
5 changed files with 491 additions and 8 deletions
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20
src/compiler/checker.ts
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@@ -26129,15 +26129,19 @@ namespace ts {
if (checkMode && checkMode & CheckMode.SkipContextSensitive && isContextSensitive(node)) {
// Skip parameters, return signature with return type that retains noncontextual parts so inferences can still be drawn in an early stage
if (!getEffectiveReturnTypeNode(node) && hasContextSensitiveReturnExpression(node)) {
const links = getNodeLinks(node);
if (links.contextFreeType) {
return links.contextFreeType;
// Return plain anyFunctionType if there is no possibility we'll make inferences from the return type
const contextualSignature = getContextualSignature(node);
if (contextualSignature && couldContainTypeVariables(getReturnTypeOfSignature(contextualSignature))) {
const links = getNodeLinks(node);
if (links.contextFreeType) {
return links.contextFreeType;
}
const returnType = getReturnTypeFromBody(node, checkMode);
const returnOnlySignature = createSignature(undefined, undefined, undefined, emptyArray, returnType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None);
const returnOnlyType = createAnonymousType(node.symbol, emptySymbols, [returnOnlySignature], emptyArray, undefined, undefined);
returnOnlyType.objectFlags |= ObjectFlags.NonInferrableType;
return links.contextFreeType = returnOnlyType;
}
const returnType = getReturnTypeFromBody(node, checkMode);
const returnOnlySignature = createSignature(undefined, undefined, undefined, emptyArray, returnType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None);
const returnOnlyType = createAnonymousType(node.symbol, emptySymbols, [returnOnlySignature], emptyArray, undefined, undefined);
returnOnlyType.objectFlags |= ObjectFlags.NonInferrableType;
return links.contextFreeType = returnOnlyType;
}
return anyFunctionType;
}