https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111512
Bug ID: 111512
Summary: GCC's __builtin_memcpy can trigger ADL
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: de34 at live dot cn
Target Milestone: ---
When using libstdc++ in GCC 14, the following program compiles with Clang but
is rejected by GCC (https://godbolt.org/z/WKbe1c3v7).
```
#include <array>
#include <utility>
struct incomplete;
template<class T>
struct holder {
T t;
};
using validator = holder<incomplete>*;
int main()
{
validator a[1]{};
(void) std::to_array(a);
(void) std::to_array(std::move(a));
}
```
The implementation can be made to work for GCC if `::` is added before the call
to __builtin_memcpy (https://godbolt.org/z/6Mx11T3f9).
So the reason for failure seems to be that GCC's __builtin_memcpy can trigger
ADL like a real function.
