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Use dedicated marker types for variance determination

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This commit is contained in:
Anders Hejlsberg 2017-09-18 13:36:46 -07:00
parent 12f5dd85d7
commit f8ff7f7365
2 changed files with 12 additions and 5 deletions
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16
src/compiler/checker.ts
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@ -282,6 +282,10 @@ namespace ts {
const noConstraintType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
const circularConstraintType = createAnonymousType(undefined, emptySymbols, emptyArray, emptyArray, undefined, undefined);
const markerSuperType = createType(TypeFlags.MarkerType);
const markerSubType = createType(TypeFlags.MarkerType);
const markerOtherType = createType(TypeFlags.MarkerType);
const anySignature = createSignature(undefined, undefined, undefined, emptyArray, anyType, /*typePredicate*/ undefined, 0, /*hasRestParameter*/ false, /*hasLiteralTypes*/ false);
const unknownSignature = createSignature(undefined, undefined, undefined, emptyArray, unknownType, /*typePredicate*/ undefined, 0, /*hasRestParameter*/ false, /*hasLiteralTypes*/ false);
const resolvingSignature = createSignature(undefined, undefined, undefined, emptyArray, anyType, /*typePredicate*/ undefined, 0, /*hasRestParameter*/ false, /*hasLiteralTypes*/ false);
@ -8944,6 +8948,10 @@ namespace ts {
if (isSimpleTypeRelatedTo(source, target, relation, reportErrors ? reportError : undefined)) return Ternary.True;
if (source.flags & TypeFlags.MarkerType && target.flags & TypeFlags.MarkerType) {
return source === markerSubType && target === markerSuperType ? Ternary.True : Ternary.False;
}
if (getObjectFlags(source) & ObjectFlags.ObjectLiteral && source.flags & TypeFlags.FreshLiteral) {
if (hasExcessProperties(<FreshObjectLiteralType>source, target, reportErrors)) {
if (reportErrors) {
@ -9367,8 +9375,6 @@ namespace ts {
if (!constraint || constraint.flags & TypeFlags.Any) {
constraint = emptyObjectType;
}
// The constraint may need to be further instantiated with its 'this' type.
constraint = getTypeWithThisArgument(constraint, source);
// Report constraint errors only if the constraint is not the empty object type
const reportConstraintErrors = reportErrors && constraint !== emptyObjectType;
if (result = isRelatedTo(constraint, target, reportConstraintErrors)) {
@ -9828,11 +9834,11 @@ namespace ts {
if (!variances) {
variances = type.variances = [];
for (const tp of typeParameters) {
const superType = getVarianceType(type, tp, stringType);
const subType = getVarianceType(type, tp, emptyStringType);
const superType = getVarianceType(type, tp, markerSuperType);
const subType = getVarianceType(type, tp, markerSubType);
let variance = (isTypeAssignableTo(subType, superType) ? Variance.Covariant : 0) |
(isTypeAssignableTo(superType, subType) ? Variance.Contravariant : 0);
if (variance === Variance.Bivariant && isTypeAssignableTo(getVarianceType(type, tp, numberType), superType)) {
if (variance === Variance.Bivariant && isTypeAssignableTo(getVarianceType(type, tp, markerOtherType), superType)) {
variance = Variance.Omnivariant;
}
variances.push(variance);

1
src/compiler/types.ts
View File

@ -3215,6 +3215,7 @@ namespace ts {
NonPrimitive = 1 << 24, // intrinsic object type
/* @internal */
JsxAttributes = 1 << 25, // Jsx attributes type
MarkerType = 1 << 26, // Marker type used for variance probing
/* @internal */
Nullable = Undefined | Null,