[clang] [Clang] Fix crash with implicit int-to-pointer conversion (PR #114218)

[Eli Friedman via cfe-commits]

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@@ -4928,8 +4928,9 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     // Look at the argument type to determine whether this is a volatile
     // operation. The parameter type is always volatile.
     QualType PtrTy = E->getArg(0)->IgnoreImpCasts()->getType();
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efriedma-quic wrote:

IgnoreImpCasts is usually wrong; in general, it's going to find an unrelated type.

If __atomic_test_and_set is overloaded to have both a volatile and non-volatile variant, it should be using custom type-checking in Sema.

https://github.com/llvm/llvm-project/pull/114218