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Add relations for keyof S / keyof T and [P in S]: X / [P in T]: X

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This commit is contained in:
Anders Hejlsberg 2016-11-08 12:21:44 -08:00
parent a562d6e63f
commit cf2953bc44
1 changed files with 37 additions and 13 deletions
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50
src/compiler/checker.ts
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@ -2229,7 +2229,7 @@ namespace ts {
// The specified symbol flags need to be reinterpreted as type flags
buildSymbolDisplay(type.symbol, writer, enclosingDeclaration, SymbolFlags.Type, SymbolFormatFlags.None, nextFlags);
}
else if (!(flags & TypeFormatFlags.InTypeAlias) && (getObjectFlags(type) & ObjectFlags.Anonymous || type.flags & TypeFlags.UnionOrIntersection) && type.aliasSymbol &&
else if (!(flags & TypeFormatFlags.InTypeAlias) && type.aliasSymbol &&
isSymbolAccessible(type.aliasSymbol, enclosingDeclaration, SymbolFlags.Type, /*shouldComputeAliasesToMakeVisible*/ false).accessibility === SymbolAccessibility.Accessible) {
const typeArguments = type.aliasTypeArguments;
writeSymbolTypeReference(type.aliasSymbol, typeArguments, 0, typeArguments ? typeArguments.length : 0, nextFlags);
@ -4488,6 +4488,14 @@ namespace ts {
return instantiateType(type.templateType, type.mapper || identityMapper);
}
function isGenericMappedType(type: Type) {
if (getObjectFlags(type) & ObjectFlags.Mapped) {
const constraintType = getConstraintTypeFromMappedType(<MappedType>type);
return !!(constraintType.flags & (TypeFlags.TypeParameter | TypeFlags.Index));
}
return false;
}
function resolveStructuredTypeMembers(type: StructuredType): ResolvedType {
if (!(<ResolvedType>type).members) {
if (type.flags & TypeFlags.Object) {
@ -6996,6 +7004,12 @@ namespace ts {
}
}
else if (target.flags & TypeFlags.Index) {
// A keyof S is related to a keyof T if T is related to S.
if (source.flags & TypeFlags.Index) {
if (result = isRelatedTo((<IndexType>target).type, (<IndexType>source).type, /*reportErrors*/ false)) {
return result;
}
}
// Given a type parameter T with a constraint C, a type S is assignable to
// keyof T if S is assignable to keyof C.
const constraint = getConstraintOfTypeParameter((<IndexType>target).type);
@ -7030,18 +7044,28 @@ namespace ts {
return result;
}
}
// Even if relationship doesn't hold for unions, intersections, or generic type references,
// it may hold in a structural comparison.
const apparentSource = getApparentType(source);
// In a check of the form X = A & B, we will have previously checked if A relates to X or B relates
// to X. Failing both of those we want to check if the aggregation of A and B's members structurally
// relates to X. Thus, we include intersection types on the source side here.
if (apparentSource.flags & (TypeFlags.Object | TypeFlags.Intersection) && target.flags & TypeFlags.Object) {
// Report structural errors only if we haven't reported any errors yet
const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo && !(source.flags & TypeFlags.Primitive);
if (result = objectTypeRelatedTo(apparentSource, source, target, reportStructuralErrors)) {
errorInfo = saveErrorInfo;
return result;
else if (isGenericMappedType(target)) {
// A type [P in S]: X is related to a type [P in T]: X if T is related to S.
if (isGenericMappedType(source) &&
isRelatedTo(getConstraintTypeFromMappedType(<MappedType>target), getConstraintTypeFromMappedType(<MappedType>source), /*reportErrors*/ false) &&
isTypeIdenticalTo(getTemplateTypeFromMappedType(<MappedType>source), getTemplateTypeFromMappedType(<MappedType>target))) {
return Ternary.True;
}
}
else {
// Even if relationship doesn't hold for unions, intersections, or generic type references,
// it may hold in a structural comparison.
const apparentSource = getApparentType(source);
// In a check of the form X = A & B, we will have previously checked if A relates to X or B relates
// to X. Failing both of those we want to check if the aggregation of A and B's members structurally
// relates to X. Thus, we include intersection types on the source side here.
if (apparentSource.flags & (TypeFlags.Object | TypeFlags.Intersection) && target.flags & TypeFlags.Object) {
// Report structural errors only if we haven't reported any errors yet
const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo && !(source.flags & TypeFlags.Primitive);
if (result = objectTypeRelatedTo(apparentSource, source, target, reportStructuralErrors)) {
errorInfo = saveErrorInfo;
return result;
}
}
}
}