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Revert type predicates to not have instanceof special casing

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This commit is contained in:
Anders Hejlsberg
2016-11-14 17:13:49 -08:00
parent 2bcb6e9812
commit d2c0952801
1 changed files with 6 additions and 6 deletions
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12
src/compiler/checker.ts
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@@ -9721,20 +9721,20 @@ namespace ts {
}
if (targetType) {
return getNarrowedType(type, targetType, assumeTrue);
return getNarrowedType(type, targetType, assumeTrue, isTypeInstanceOf);
}
return type;
}
function getNarrowedType(type: Type, candidate: Type, assumeTrue: boolean) {
function getNarrowedType(type: Type, candidate: Type, assumeTrue: boolean, isRelated: (source: Type, target: Type) => boolean) {
if (!assumeTrue) {
return filterType(type, t => !isTypeInstanceOf(t, candidate));
return filterType(type, t => !isRelated(t, candidate));
}
// If the current type is a union type, remove all constituents that couldn't be instances of
// the candidate type. If one or more constituents remain, return a union of those.
if (type.flags & TypeFlags.Union) {
const assignableType = filterType(type, t => isTypeInstanceOf(t, candidate));
const assignableType = filterType(type, t => isRelated(t, candidate));
if (!(assignableType.flags & TypeFlags.Never)) {
return assignableType;
}
@@ -9770,7 +9770,7 @@ namespace ts {
const predicateArgument = callExpression.arguments[predicate.parameterIndex];
if (predicateArgument) {
if (isMatchingReference(reference, predicateArgument)) {
return getNarrowedType(type, predicate.type, assumeTrue);
return getNarrowedType(type, predicate.type, assumeTrue, isTypeSubtypeOf);
}
if (containsMatchingReference(reference, predicateArgument)) {
return declaredType;
@@ -9783,7 +9783,7 @@ namespace ts {
const accessExpression = invokedExpression as ElementAccessExpression | PropertyAccessExpression;
const possibleReference = skipParentheses(accessExpression.expression);
if (isMatchingReference(reference, possibleReference)) {
return getNarrowedType(type, predicate.type, assumeTrue);
return getNarrowedType(type, predicate.type, assumeTrue, isTypeSubtypeOf);
}
if (containsMatchingReference(reference, possibleReference)) {
return declaredType;