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

[Alexander Kornienko via libcxx-commits]

alexfh wrote:

I found an interesting interaction between this and the `DoNotOptimize` from the Google Benchmark library: https://gcc.godbolt.org/z/4EKdf8EWP

In short, DoNotOptimize stopped compiling for std::unique_ptr with a custom deleter. 
```
error: invalid lvalue in asm output
    7 |   asm volatile("" : "+r,m"(var) : : "memory");
      |                            ^~~
<source>:30:3: note: in instantiation of function template specialization 'DoNotOptimize<std::unique_ptr<int[], Delete<int, std::allocator<int>>>>' requested here
   30 |   DoNotOptimize(ptr);
      |   ^
```

That seems to be quite a rare case though.

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