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Narrowing of in handles string index signatures

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This commit is contained in:
Nathan Shively-Sanders 2017-12-07 10:57:15 -08:00
parent 3a0ce3435e
commit d75ebd6a33
1 changed files with 5 additions and 2 deletions
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7
src/compiler/checker.ts
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@ -12723,9 +12723,12 @@ namespace ts {
}
function isTypePresencePossible(type: Type, propName: __String, assumeTrue: boolean) {
if (getIndexInfoOfType(type, IndexKind.String)) {
return true;
}
const prop = getPropertyOfType(type, propName);
if (prop) {
return (prop.flags & SymbolFlags.Optional) ? true : assumeTrue;
return prop.flags & SymbolFlags.Optional ? true : assumeTrue;
}
return !assumeTrue;
}
@ -12733,7 +12736,7 @@ namespace ts {
function narrowByInKeyword(type: Type, literal: LiteralExpression, assumeTrue: boolean) {
if ((type.flags & (TypeFlags.Union | TypeFlags.Object)) || (type.flags & TypeFlags.TypeParameter && (type as TypeParameter).isThisType)) {
const propName = escapeLeadingUnderscores(literal.text);
return filterType(type, t => isTypePresencePossible(t, propName, /* assumeTrue */ assumeTrue));
return filterType(type, t => isTypePresencePossible(t, propName, assumeTrue));
}
return type;
}