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Properly handle recursive type references in type inference

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This commit is contained in:
Anders Hejlsberg
2019-09-30 08:54:02 -07:00
parent 20e2be1e1a
commit ed497c4149
1 changed files with 9 additions and 2 deletions
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src/compiler/checker.ts
+9 -2
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@@ -17021,7 +17021,7 @@ namespace ts {
function couldContainTypeVariables(type: Type): boolean {
const objectFlags = getObjectFlags(type);
return !!(type.flags & TypeFlags.Instantiable ||
objectFlags & ObjectFlags.Reference && forEach(getTypeArguments(<TypeReference>type), couldContainTypeVariables) ||
objectFlags & ObjectFlags.Reference && ((<TypeReference>type).node || forEach(getTypeArguments(<TypeReference>type), couldContainTypeVariables)) ||
objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral) && type.symbol.declarations ||
objectFlags & ObjectFlags.Mapped ||
type.flags & TypeFlags.UnionOrIntersection && !(type.flags & TypeFlags.EnumLiteral) && couldUnionOrIntersectionContainTypeVariables(<UnionOrIntersectionType>type));
@@ -17318,7 +17318,8 @@ namespace ts {
}
}
if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (
(<TypeReference>source).target === (<TypeReference>target).target || isArrayType(source) && isArrayType(target))) {
(<TypeReference>source).target === (<TypeReference>target).target || isArrayType(source) && isArrayType(target)) &&
!((<TypeReference>source).node && (<TypeReference>target).node)) {
// If source and target are references to the same generic type, infer from type arguments
inferFromTypeArguments(getTypeArguments(<TypeReference>source), getTypeArguments(<TypeReference>target), getVariances((<TypeReference>source).target));
}
@@ -17599,6 +17600,12 @@ namespace ts {
}
function inferFromObjectTypesWorker(source: Type, target: Type) {
if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (
(<TypeReference>source).target === (<TypeReference>target).target || isArrayType(source) && isArrayType(target))) {
// If source and target are references to the same generic type, infer from type arguments
inferFromTypeArguments(getTypeArguments(<TypeReference>source), getTypeArguments(<TypeReference>target), getVariances((<TypeReference>source).target));
return;
}
if (isGenericMappedType(source) && isGenericMappedType(target)) {
// The source and target types are generic types { [P in S]: X } and { [P in T]: Y }, so we infer
// from S to T and from X to Y.