[clang] [Clang] Handle ?: operator in fold expression (PR #164019)

[via cfe-commits]

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@@ -1510,7 +1510,7 @@ static void CheckFoldOperand(Sema &S, Expr *E) {
   E = E->IgnoreImpCasts();
   auto *OCE = dyn_cast<CXXOperatorCallExpr>(E);
   if ((OCE && OCE->isInfixBinaryOp()) || isa<BinaryOperator>(E) ||
-      isa<AbstractConditionalOperator>(E)) {
+      isa<AbstractConditionalOperator>(E) || isa<RecoveryExpr>(E)) {
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Sirraide wrote:

> IIUC the frontend produces a RecoveryExpr on semantic errors that prevent forming well formed statements. In that case should it be always generated in case of semantic errors? Can you point an example where it is not always generated.

`RecoveryExpr`s are only created if they’re enabled by some flag (`-frecovery-ast` iirc), otherwise, you just get `ExprError()`:
https://github.com/llvm/llvm-project/blob/f42e58f61680e325555f382cab5115c54df6f6df/clang/lib/Sema/SemaExpr.cpp#L21591-L21594

https://github.com/llvm/llvm-project/pull/164019