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Merge pull request #41191 from weswigham/control-flow-comma-exprs

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Track control flow for comma expressions in call expressions
This commit is contained in:
Wesley Wigham
2020-10-27 12:37:02 -07:00
committed by GitHub
parent aaa8b74229 6dde1621cb
commit c923023494
6 changed files with 95 additions and 1 deletions
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1
src/compiler/binder.ts
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@@ -859,6 +859,7 @@ namespace ts {
function isNarrowableReference(expr: Expression): boolean {
return expr.kind === SyntaxKind.Identifier || expr.kind === SyntaxKind.PrivateIdentifier || expr.kind === SyntaxKind.ThisKeyword || expr.kind === SyntaxKind.SuperKeyword ||
(isPropertyAccessExpression(expr) || isNonNullExpression(expr) || isParenthesizedExpression(expr)) && isNarrowableReference(expr.expression) ||
isBinaryExpression(expr) && expr.operatorToken.kind === SyntaxKind.CommaToken && isNarrowableReference(expr.right) ||
isElementAccessExpression(expr) && isStringOrNumericLiteralLike(expr.argumentExpression) && isNarrowableReference(expr.expression) ||
isAssignmentExpression(expr) && isNarrowableReference(expr.left);
}

3
src/compiler/checker.ts
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@@ -20777,7 +20777,8 @@ namespace ts {
case SyntaxKind.NonNullExpression:
return isMatchingReference(source, (target as NonNullExpression | ParenthesizedExpression).expression);
case SyntaxKind.BinaryExpression:
return isAssignmentExpression(target) && isMatchingReference(source, target.left);
return (isAssignmentExpression(target) && isMatchingReference(source, target.left)) ||
(isBinaryExpression(target) && target.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source, target.right));
}
switch (source.kind) {
case SyntaxKind.Identifier: