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Use more permissive wildcard type in definitely false check

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This commit is contained in:
Anders Hejlsberg
2018-02-05 06:48:29 -08:00
parent 3ef1b56ee9
commit b8f3c6169b
2 changed files with 11 additions and 9 deletions
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18
src/compiler/checker.ts
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@@ -315,6 +315,7 @@ namespace ts {
const anyType = createIntrinsicType(TypeFlags.Any, "any");
const autoType = createIntrinsicType(TypeFlags.Any, "any");
const wildcardType = createIntrinsicType(TypeFlags.Any, "any");
const unknownType = createIntrinsicType(TypeFlags.Any, "unknown");
const undefinedType = createIntrinsicType(TypeFlags.Undefined, "undefined");
const undefinedWideningType = strictNullChecks ? undefinedType : createIntrinsicType(TypeFlags.Undefined | TypeFlags.ContainsWideningType, "undefined");
@@ -8150,9 +8151,10 @@ namespace ts {
// Instantiate extends type without instantiating any 'infer T' type parameters
const extendsType = instantiateType(baseExtendsType, mapper);
// Return falseType for a definitely false extends check. We check an instantations of the two
// types with type parameters mapped to any, the most permissive instantiations possible. If those
// are not related, then no instatiations will be and we can just return the false branch type.
if (!isTypeAssignableTo(getAnyInstantiation(checkType), getAnyInstantiation(extendsType))) {
// types with type parameters mapped to the wildcard type, the most permissive instantiations
// possible (the wildcard type is assignable to and from all types). If those are not related,
// then no instatiations will be and we can just return the false branch type.
if (!isTypeAssignableTo(getWildcardInstantiation(checkType), getWildcardInstantiation(extendsType))) {
return instantiateType(baseFalseType, mapper);
}
// The check could be true for some instantiation
@@ -8615,8 +8617,8 @@ namespace ts {
return t => t === source ? target : baseMapper(t);
}
function anyMapper(type: Type) {
return type.flags & TypeFlags.TypeParameter ? anyType : type;
function wildcardMapper(type: Type) {
return type.flags & TypeFlags.TypeParameter ? wildcardType : type;
}
function cloneTypeParameter(typeParameter: TypeParameter): TypeParameter {
@@ -8873,9 +8875,9 @@ namespace ts {
return type;
}
function getAnyInstantiation(type: Type) {
function getWildcardInstantiation(type: Type) {
return type.flags & (TypeFlags.Primitive | TypeFlags.Any | TypeFlags.Never) ? type :
type.resolvedAnyInstantiation || (type.resolvedAnyInstantiation = instantiateType(type, anyMapper));
type.wildcardInstantiation || (type.wildcardInstantiation = instantiateType(type, wildcardMapper));
}
function instantiateIndexInfo(info: IndexInfo, mapper: TypeMapper): IndexInfo {
@@ -9282,7 +9284,7 @@ namespace ts {
function isSimpleTypeRelatedTo(source: Type, target: Type, relation: Map<RelationComparisonResult>, errorReporter?: ErrorReporter) {
const s = source.flags;
const t = target.flags;
if (t & TypeFlags.Any || s & TypeFlags.Never) return true;
if (t & TypeFlags.Any || s & TypeFlags.Never || source === wildcardType) return true;
if (t & TypeFlags.Never) return false;
if (s & TypeFlags.StringLike && t & TypeFlags.String) return true;
if (s & TypeFlags.StringLiteral && s & TypeFlags.EnumLiteral &&

2
src/compiler/types.ts
View File

@@ -3564,7 +3564,7 @@ namespace ts {
aliasSymbol?: Symbol; // Alias associated with type
aliasTypeArguments?: Type[]; // Alias type arguments (if any)
/* @internal */
resolvedAnyInstantiation?: Type; // Instantiation with type parameters mapped to any
wildcardInstantiation?: Type; // Instantiation with type parameters mapped to wildcard type
}
/* @internal */