[clang] [clang][ObjC][CodeComplete] Fix crash on C-Style cast with parenthesized operand in ObjC++ (PR #180343)

[via cfe-commits]

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@@ -5152,7 +5152,7 @@ void SemaCodeCompletion::CodeCompletePostfixExpression(Scope *S, ExprResult E,
                                                        QualType PreferredType) {
   if (E.isInvalid())
     CodeCompleteExpression(S, PreferredType);
-  else if (getLangOpts().ObjC)
+  else if (getLangOpts().ObjC && !E.get()->getType().isNull())
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edisongz wrote:

> but there's no reason to leave the hazard

Thanks for the feedback. Moved the guard into `CodeCompleteObjCInstanceMessage` as suggested.

https://github.com/llvm/llvm-project/pull/180343