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Add T is related to { [P in xxx]: T[P] } type relationship

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This commit is contained in:
Anders Hejlsberg
2018-01-19 17:06:09 -08:00
parent 0e73240ea4
commit 5204fd5c5f
2 changed files with 17 additions and 7 deletions
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22
src/compiler/checker.ts
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@@ -6968,7 +6968,7 @@ namespace ts {
// type references and type alias instantiations because subsitution types are no longer necessary once
// the type arguments have been validated against their corresponding type parameter constraints.
function eraseSubstitutionType(type: Type) {
return type.flags & TypeFlags.Substitution ? (<SubstitutionType>type).typeParameter : type
return type.flags & TypeFlags.Substitution ? (<SubstitutionType>type).typeParameter : type;
}
function createTypeReference(target: GenericType, typeArguments: Type[]): TypeReference {
@@ -9821,13 +9821,21 @@ namespace ts {
}
}
}
else if (isGenericMappedType(target) && !isGenericMappedType(source) && getConstraintTypeFromMappedType(<MappedType>target) === getIndexType(source)) {
else if (isGenericMappedType(target)) {
// A source type T is related to a target type { [P in X]: T[P] }
const template = getTemplateTypeFromMappedType(<MappedType>target);
if (template.flags & TypeFlags.IndexedAccess && (<IndexedAccessType>template).objectType === source &&
(<IndexedAccessType>template).indexType === getTypeParameterFromMappedType(<MappedType>target)) {
return Ternary.True;
}
// A source type T is related to a target type { [P in keyof T]: X } if T[P] is related to X.
const indexedAccessType = getIndexedAccessType(source, getTypeParameterFromMappedType(<MappedType>target));
const templateType = getTemplateTypeFromMappedType(<MappedType>target);
if (result = isRelatedTo(indexedAccessType, templateType, reportErrors)) {
errorInfo = saveErrorInfo;
return result;
if (!isGenericMappedType(source) && getConstraintTypeFromMappedType(<MappedType>target) === getIndexType(source)) {
const indexedAccessType = getIndexedAccessType(source, getTypeParameterFromMappedType(<MappedType>target));
const templateType = getTemplateTypeFromMappedType(<MappedType>target);
if (result = isRelatedTo(indexedAccessType, templateType, reportErrors)) {
errorInfo = saveErrorInfo;
return result;
}
}
}

2
src/compiler/types.ts
View File

@@ -3794,7 +3794,9 @@ namespace ts {
extendsType: Type;
trueType: Type;
falseType: Type;
/* @internal */
target?: ConditionalType;
/* @internal */
mapper?: TypeMapper;
}