https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105505
Bug ID: 105505
Summary: P1951R1 (Default Arguments for pair's Forwarding
Constructor) is unimplemented
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: ensadc at mailnesia dot com
CC: redi at gcc dot gnu.org
Target Milestone: ---
https://en.cppreference.com/w/cpp/compiler_support claims that P1951R1 (Default
Arguments for pair's Forwarding Constructor) is supported in GCC libstdc++ 12,
but it seems that libstdc++ 12 doesn't actually add default template arguments
for said forwarding constructor.
For example, the following still does not work with libstdc++ (but works with
latest libc++ and MSVC STL: https://godbolt.org/z/6oY3G77oT).
```
#include <utility>
struct MoveOnly {
MoveOnly();
MoveOnly(MoveOnly&&);
};
std::pair<int, MoveOnly> p{42, {}};
```
