microsoft/TypeScript
1
0
Fork 0
mirror of https://github.com/microsoft/TypeScript.git synced 2026-06-07 12:25:09 -05:00
Code Issues Packages Projects Releases 212 Wiki Activity

Grab the left type when narrowing by in operator lazily (#54795)

Browse Source
This commit is contained in:
Mateusz Burzyński
2023-07-19 16:46:19 +02:00
committed by GitHub
parent ef0422b40f
commit adf5e8443b
5 changed files with 348 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
src/compiler/checker.ts
View File

@@ -27175,14 +27175,16 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return narrowTypeByPrivateIdentifierInInExpression(type, expr, assumeTrue);
}
const target = getReferenceCandidate(expr.right);
const leftType = getTypeOfExpression(expr.left);
if (leftType.flags & TypeFlags.StringOrNumberLiteralOrUnique) {
if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target) &&
getAccessedPropertyName(reference) === getPropertyNameFromType(leftType as StringLiteralType | NumberLiteralType | UniqueESSymbolType)) {
if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target)) {
const leftType = getTypeOfExpression(expr.left);
if (isTypeUsableAsPropertyName(leftType) && getAccessedPropertyName(reference) === getPropertyNameFromType(leftType)) {
return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined);
}
if (isMatchingReference(reference, target)) {
return narrowTypeByInKeyword(type, leftType as StringLiteralType | NumberLiteralType | UniqueESSymbolType, assumeTrue);
}
if (isMatchingReference(reference, target)) {
const leftType = getTypeOfExpression(expr.left);
if (isTypeUsableAsPropertyName(leftType)) {
return narrowTypeByInKeyword(type, leftType, assumeTrue);
}
}
break;