microsoft/TypeScript
1
0
Fork 0
mirror of https://github.com/microsoft/TypeScript.git synced 2026-05-19 01:33:15 -05:00
Code Issues Packages Projects Releases 212 Wiki Activity

Instantiate generic conditional infer source types in the context of the target conditional (#31545)

Browse Source 
* Instantiate generic conditional infer source types in the context of the target conditional

* Add test case from #26627
This commit is contained in:
Wesley Wigham
2019-08-19 13:01:08 -07:00
committed by GitHub
parent d75de60548
commit fd1e22bbf1
5 changed files with 253 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
src/compiler/checker.ts
View File

@@ -13527,9 +13527,19 @@ namespace ts {
// Two conditional types 'T1 extends U1 ? X1 : Y1' and 'T2 extends U2 ? X2 : Y2' are related if
// one of T1 and T2 is related to the other, U1 and U2 are identical types, X1 is related to X2,
// and Y1 is related to Y2.
if (isTypeIdenticalTo((<ConditionalType>source).extendsType, (<ConditionalType>target).extendsType) &&
const sourceParams = (source as ConditionalType).root.inferTypeParameters;
let sourceExtends = (<ConditionalType>source).extendsType;
let mapper: TypeMapper | undefined;
if (sourceParams) {
// If the source has infer type parameters, we instantiate them in the context of the target
const ctx = createInferenceContext(sourceParams, /*signature*/ undefined, InferenceFlags.None, isRelatedTo);
inferTypes(ctx.inferences, (<ConditionalType>target).extendsType, sourceExtends, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict);
sourceExtends = instantiateType(sourceExtends, ctx.mapper);
mapper = ctx.mapper;
}
if (isTypeIdenticalTo(sourceExtends, (<ConditionalType>target).extendsType) &&
(isRelatedTo((<ConditionalType>source).checkType, (<ConditionalType>target).checkType) || isRelatedTo((<ConditionalType>target).checkType, (<ConditionalType>source).checkType))) {
if (result = isRelatedTo(getTrueTypeFromConditionalType(<ConditionalType>source), getTrueTypeFromConditionalType(<ConditionalType>target), reportErrors)) {
if (result = isRelatedTo(instantiateType(getTrueTypeFromConditionalType(<ConditionalType>source), mapper), getTrueTypeFromConditionalType(<ConditionalType>target), reportErrors)) {
result &= isRelatedTo(getFalseTypeFromConditionalType(<ConditionalType>source), getFalseTypeFromConditionalType(<ConditionalType>target), reportErrors);
}
if (result) {