[libcxx-commits] [libcxx] [libc++] Replace `__compressed_pair` with `[[no_unique_address]]` (PR #76756)

[Pavel Labath via libcxx-commits]

labath wrote:

Could be. I think that's the issue I am remembering. FWIW, the reproducer for this part is quite simple:
```
$ cat /tmp/a.cc
#include <string>

std::string s;

int main() {
  return alignof(s);
}
$ bin/clang++ /tmp/a.cc -o /tmp/a.o -c -g -fstandalone-debug -stdlib=libc++ # Make sure libc++ uses the unstable ABI
/tmp/a.cc:6:10: warning: 'alignof' applied to an expression is a GNU extension [-Wgnu-alignof-expression]
    6 |   return alignof(s);
      |          ^
1 warning generated.
$ lldb /tmp/a.o -x -o 'script lldb.target.FindFirstType("::std::__2::string").GetByteAlign()'
(lldb) target create "/tmp/a.o"
Current executable set to '/tmp/a.o' (x86_64).
(lldb) script lldb.target.FindFirstType("::std::__2::string").GetByteAlign()
1
```


https://github.com/llvm/llvm-project/pull/76756