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Improve conditional type constraint checking

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This commit is contained in:
Anders Hejlsberg
2017-12-13 15:07:16 -08:00
parent ddc631c5d4
commit 000f121d34
1 changed files with 10 additions and 10 deletions
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20
src/compiler/checker.ts
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@@ -6297,7 +6297,8 @@ namespace ts {
function getConstraintOfType(type: InstantiableType | UnionOrIntersectionType): Type {
return type.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(<TypeParameter>type) :
type.flags & TypeFlags.IndexedAccess ? getConstraintOfIndexedAccess(<IndexedAccessType>type) :
getBaseConstraintOfType(type);
type.flags & TypeFlags.Conditional ? getConstraintOfConditionalType(<ConditionalType>type) :
getBaseConstraintOfType(type);
}
function getConstraintOfTypeParameter(typeParameter: TypeParameter): Type {
@@ -6314,6 +6315,10 @@ namespace ts {
return baseObjectType || baseIndexType ? getIndexedAccessType(baseObjectType || type.objectType, baseIndexType || type.indexType) : undefined;
}
function getConstraintOfConditionalType(type: ConditionalType) {
return getUnionType([type.trueType, type.falseType]);
}
function getBaseConstraintOfType(type: Type): Type {
if (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.UnionOrIntersection)) {
const constraint = getResolvedBaseConstraint(<InstantiableType | UnionOrIntersectionType>type);
@@ -6393,9 +6398,7 @@ namespace ts {
return baseIndexedAccess && baseIndexedAccess !== unknownType ? getBaseConstraint(baseIndexedAccess) : undefined;
}
if (t.flags & TypeFlags.Conditional) {
const trueBaseType = getBaseConstraint((<ConditionalType>t).trueType);
const falseBaseType = getBaseConstraint((<ConditionalType>t).falseType);
return trueBaseType && falseBaseType ? getUnionType([trueBaseType, falseBaseType]) : undefined;
return getBaseConstraint(getConstraintOfConditionalType(<ConditionalType>t));
}
if (t.flags & TypeFlags.Extends) {
return booleanType;
@@ -9988,12 +9991,9 @@ namespace ts {
}
}
else if (source.flags & TypeFlags.Conditional) {
const constraint = getConstraintOfType(source);
if (constraint) {
if (result = isRelatedTo(constraint, target, reportErrors)) {
errorInfo = saveErrorInfo;
return result;
}
if (result = isRelatedTo(getConstraintOfConditionalType(<ConditionalType>source), target, reportErrors)) {
errorInfo = saveErrorInfo;
return result;
}
}
else {