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Improve contextually typed parameters with initializers (#56506)

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This commit is contained in:
Mateusz Burzyński
2023-12-05 19:56:02 +01:00
committed by GitHub
parent 6c0687e493
commit 993ffd70e6
15 changed files with 538 additions and 199 deletions
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13
src/compiler/checker.ts
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@@ -36221,9 +36221,16 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0);
for (let i = 0; i < len; i++) {
const parameter = signature.parameters[i];
if (!getEffectiveTypeAnnotationNode(parameter.valueDeclaration as ParameterDeclaration)) {
const contextualParameterType = tryGetTypeAtPosition(context, i);
assignParameterType(parameter, contextualParameterType);
const declaration = parameter.valueDeclaration as ParameterDeclaration;
if (!getEffectiveTypeAnnotationNode(declaration)) {
let type = tryGetTypeAtPosition(context, i);
if (type && declaration.initializer) {
let initializerType = checkDeclarationInitializer(declaration, CheckMode.Normal);
if (!isTypeAssignableTo(initializerType, type) && isTypeAssignableTo(type, initializerType = widenTypeInferredFromInitializer(declaration, initializerType))) {
type = initializerType;
}
}
assignParameterType(parameter, type);
}
}
if (signatureHasRestParameter(signature)) {