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Include fresh type parameters in type parameter mapper function

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This commit is contained in:
Anders Hejlsberg
2015-12-10 12:07:17 -08:00
parent 30dbf9c48e
commit 9810ddf326
1 changed files with 9 additions and 9 deletions
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src/compiler/checker.ts
+9 -9
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@@ -4744,16 +4744,10 @@ namespace ts {
return t => instantiateType(mapper1(t), mapper2);
}
function instantiateTypeParameter(typeParameter: TypeParameter, mapper: TypeMapper): TypeParameter {
function cloneTypeParameter(typeParameter: TypeParameter): TypeParameter {
const result = <TypeParameter>createType(TypeFlags.TypeParameter);
result.symbol = typeParameter.symbol;
if (typeParameter.constraint) {
result.constraint = instantiateType(typeParameter.constraint, mapper);
}
else {
result.target = typeParameter;
result.mapper = mapper;
}
result.target = typeParameter;
return result;
}
@@ -4761,8 +4755,14 @@ namespace ts {
let freshTypeParameters: TypeParameter[];
let freshTypePredicate: TypePredicate;
if (signature.typeParameters && !eraseTypeParameters) {
freshTypeParameters = instantiateList(signature.typeParameters, mapper, instantiateTypeParameter);
// First create a fresh set of type parameters, then include a mapping from the old to the
// new type parameters in the mapper function. Finally store this mapper in the new type
// parameters such that we can use it when instantiating constraints.
freshTypeParameters = map(signature.typeParameters, cloneTypeParameter);
mapper = combineTypeMappers(createTypeMapper(signature.typeParameters, freshTypeParameters), mapper);
for (const tp of freshTypeParameters) {
tp.mapper = mapper;
}
}
if (signature.typePredicate) {
freshTypePredicate = {