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Exclude generic string-like types from intersection reduction (#57751)

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This commit is contained in:
Anders Hejlsberg
2024-03-13 16:13:31 -07:00
committed by GitHub
parent f9ef9439bd
commit 952dfc5082
4 changed files with 161 additions and 2 deletions
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src/compiler/checker.ts
+9 -2
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@@ -17642,7 +17642,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const typeVarIndex = typeSet[0].flags & TypeFlags.TypeVariable ? 0 : 1;
const typeVariable = typeSet[typeVarIndex];
const primitiveType = typeSet[1 - typeVarIndex];
if (typeVariable.flags & TypeFlags.TypeVariable && (primitiveType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) || includes & TypeFlags.IncludesEmptyObject)) {
if (
typeVariable.flags & TypeFlags.TypeVariable &&
(primitiveType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) && !isGenericStringLikeType(primitiveType) || includes & TypeFlags.IncludesEmptyObject)
) {
// We have an intersection T & P or P & T, where T is a type variable and P is a primitive type, the object type, or {}.
const constraint = getBaseConstraintOfType(typeVariable);
// Check that T's constraint is similarly composed of primitive types, the object type, or {}.
@@ -18389,6 +18392,10 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
!!(type.flags & TypeFlags.StringMapping) && isPatternLiteralPlaceholderType((type as StringMappingType).type);
}
function isGenericStringLikeType(type: Type) {
return !!(type.flags & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) && !isPatternLiteralType(type);
}
function isGenericType(type: Type): boolean {
return !!getGenericObjectFlags(type);
}
@@ -18417,7 +18424,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return (type as SubstitutionType).objectFlags & ObjectFlags.IsGenericType;
}
return (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type) || isGenericTupleType(type) ? ObjectFlags.IsGenericObjectType : 0) |
(type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && !isPatternLiteralType(type) ? ObjectFlags.IsGenericIndexType : 0);
(type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.Index) || isGenericStringLikeType(type) ? ObjectFlags.IsGenericIndexType : 0);
}
function getSimplifiedType(type: Type, writing: boolean): Type {