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Contextual typing by tuple rest elements

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This commit is contained in:
Anders Hejlsberg 2018-06-25 10:45:02 -10:00
parent 3cc3b49030
commit d7443f04fd
1 changed files with 13 additions and 2 deletions
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15
src/compiler/checker.ts
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@ -15531,8 +15531,19 @@ namespace ts {
function getTypeOfPropertyOfContextualType(type: Type, name: __String) {
return mapType(type, t => {
const prop = t.flags & TypeFlags.StructuredType ? getPropertyOfType(t, name) : undefined;
return prop ? getTypeOfSymbol(prop) : undefined;
if (t.flags & TypeFlags.StructuredType) {
const prop = getPropertyOfType(t, name);
if (prop) {
return getTypeOfSymbol(prop);
}
if (isTupleType(t)) {
const restType = getRestTypeOfTupleType(t);
if (restType && isNumericLiteralName(name) && +name >= 0) {
return restType;
}
}
}
return undefined;
}, /*noReductions*/ true);
}