[clang] [Analyzer][CFG] Correctly handle rebuilt default arg and default init expression (PR #117437)

[Erich Keane via cfe-commits]

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@@ -5570,8 +5570,10 @@ ExprResult Sema::BuildCXXDefaultArgExpr(SourceLocation CallLoc,
           /*SkipImmediateInvocations=*/NestedDefaultChecking))
     return ExprError();
 
+  Expr *RewrittenExpr = Init == Param->getDefaultArg() ? nullptr : Init;
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erichkeane wrote:

```suggestion
  Expr *RewrittenExpr = (Init == Param->getDefaultArg() ? nullptr : Init);
```

MINOR preference to reverse this condition?  But not sure enough to suggest this.

https://github.com/llvm/llvm-project/pull/117437