| Issue |
91266
|
| Summary |
[libc++] Falsely rejected code for `std::unique_ptr` because `__compressed_pair` requires different types.
|
| Labels |
libc++
|
| Assignees |
|
| Reporter |
SainoNamkho
|
As shown in https://godbolt.org/z/4K6q9bo3e, only libc++
```c++
#include <memory>
#include <any>
void f(std::any) {}
std::unique_ptr<decltype(f), decltype(f)*> p(f, f);
```
I've not found anywhere in the draft saying this should be rejected.
1. Why does `__compressed_pair` require the two template arguments to be the same and the `_CanBeEmptyBase` traits? If they makes it unable to compress, then an uncompressed layout is automatically produced, with no need to be explicitly rejected. And the indices used by `__compressed_pair_elem` suggest that it handles same types correctly.
2. If it is reasonable to keep the implementation of `__compressed_pair`, is it a good solution to change `unique_ptr` into use something like `conditional_t<same_as<pointer, deleter_type>, __compressed_pair<<pointer, deleter_type>, ...>`?
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