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Fix inferences between alias type arguments and defaulted alias type arguments (#51771)

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This commit is contained in:
Wesley Wigham
2023-01-11 15:28:53 -08:00
committed by GitHub
parent 6860373c1a
commit 9da2a9aa84
5 changed files with 364 additions and 3 deletions
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14
src/compiler/checker.ts
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@@ -20871,7 +20871,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (variances === emptyArray) {
return Ternary.Unknown;
}
const varianceResult = relateVariances(source.aliasTypeArguments, target.aliasTypeArguments, variances, intersectionState);
const params = getSymbolLinks(source.aliasSymbol).typeParameters!;
const minParams = getMinTypeArgumentCount(params);
const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
const varianceResult = relateVariances(sourceTypes, targetTypes, variances, intersectionState);
if (varianceResult !== undefined) {
return varianceResult;
}
@@ -23805,8 +23809,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (source.aliasSymbol && source.aliasSymbol === target.aliasSymbol) {
if (source.aliasTypeArguments) {
// Source and target are types originating in the same generic type alias declaration.
// Simply infer from source type arguments to target type arguments.
inferFromTypeArguments(source.aliasTypeArguments, target.aliasTypeArguments!, getAliasVariances(source.aliasSymbol));
// Simply infer from source type arguments to target type arguments, with defaults applied.
const params = getSymbolLinks(source.aliasSymbol).typeParameters!;
const minParams = getMinTypeArgumentCount(params);
const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
inferFromTypeArguments(sourceTypes, targetTypes!, getAliasVariances(source.aliasSymbol));
}
// And if there weren't any type arguments, there's no reason to run inference as the types must be the same.
return;