[clang] [Clang] Introduce __builtin_is_modifiable_lvalue() (PR #132524)

[via cfe-commits]

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@@ -12985,6 +12985,16 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
     assert(Src.isInt());
     return Success((Src.getInt() & (Alignment - 1)) == 0 ? 1 : 0, E);
   }
+  case Builtin::BI__builtin_is_modifiable_lvalue: {
+    const Expr *Arg = E->getArg(0);
+    SpeculativeEvaluationRAII SpeculativeEval(Info);
+    IgnoreSideEffectsRAII Fold(Info);
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Sirraide wrote:

```suggestion
```
As was already pointed out (I think), we don’t need these here since we’re not doing any evaluating anyway.

https://github.com/llvm/llvm-project/pull/132524