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Properly reduce intersections of string literal and template literal types (#41162)

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* Properly reduce single element intersections

* Add regression test

* Accept new baselines
This commit is contained in:
Anders Hejlsberg
2020-10-19 13:05:29 -07:00
committed by GitHub
parent 15cec9d1f7
commit 4638c685b1
6 changed files with 43 additions and 9 deletions
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10
src/compiler/checker.ts
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@@ -13373,6 +13373,9 @@ namespace ts {
includes & TypeFlags.VoidLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.VoidLike)) {
return neverType;
}
if (includes & TypeFlags.TemplateLiteral && includes & TypeFlags.StringLiteral && extractRedundantTemplateLiterals(typeSet)) {
return neverType;
}
if (includes & TypeFlags.Any) {
return includes & TypeFlags.IncludesWildcard ? wildcardType : anyType;
}
@@ -13424,12 +13427,7 @@ namespace ts {
}
}
else {
if (includes & TypeFlags.TemplateLiteral && includes & TypeFlags.StringLiteral && extractRedundantTemplateLiterals(typeSet)) {
result = neverType;
}
else {
result = createIntersectionType(typeSet, aliasSymbol, aliasTypeArguments);
}
result = createIntersectionType(typeSet, aliasSymbol, aliasTypeArguments);
}
intersectionTypes.set(id, result);
}