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Support intersection types as target in type inference

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This commit is contained in:
Anders Hejlsberg 2015-06-30 12:23:21 -07:00
parent c517a6341e
commit 6ae775b4ff
1 changed files with 6 additions and 5 deletions
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11
src/compiler/checker.ts
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@ -5408,11 +5408,11 @@ namespace ts {
inferFromTypes(sourceTypes[i], targetTypes[i]);
}
}
else if (target.flags & TypeFlags.Union) {
let targetTypes = (<UnionType>target).types;
else if (target.flags & TypeFlags.UnionOrIntersection) {
let targetTypes = (<UnionOrIntersectionType>target).types;
let typeParameterCount = 0;
let typeParameter: TypeParameter;
// First infer to each type in union that isn't a type parameter
// First infer to each type in union or intersection that isn't a type parameter
for (let t of targetTypes) {
if (t.flags & TypeFlags.TypeParameter && contains(context.typeParameters, t)) {
typeParameter = <TypeParameter>t;
@ -5422,8 +5422,9 @@ namespace ts {
inferFromTypes(source, t);
}
}
// If union contains a single naked type parameter, make a secondary inference to that type parameter
if (typeParameterCount === 1) {
// Next, if target is a union type containing a single naked type parameter, make a
// secondary inference to that type parameter
if (target.flags & TypeFlags.Union && typeParameterCount === 1) {
inferiority++;
inferFromTypes(source, typeParameter);
inferiority--;