[libcxx-commits] [libcxx] [libc++] Prevent ADL on _Block_copy/_Block_release (PR #179614)

[A. Jiang via libcxx-commits]

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@@ -540,7 +540,7 @@ class __func<_Rp1 (^)(_ArgTypes1...), _Rp(_ArgTypes...)> : public __base<_Rp(_Ar
 #    if __has_feature(objc_arc)
       : __f_(__f)
 #    else
-      : __f_(reinterpret_cast<__block_type>(__f ? _Block_copy(__f) : nullptr))
+      : __f_(reinterpret_cast<__block_type>(__f ? (_Block_copy)(__f) : nullptr))
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frederick-vs-ja wrote:

Looks a bit weird to me. Can we use `::_Block_copy` instead? Ditto below.

Also, I think we should add test for this which uses "ADL-bomb" types, e.g.
```C++
struct incomplete;

template <class T>
struct holder { T t; };

using adl_unfriendly_block = holder<incomplete>* (^)();
```

https://github.com/llvm/llvm-project/pull/179614