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

[Azmat Yusuf via cfe-commits]

================
@@ -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)) {
----------------
azmat-y 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. 

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