[Bug c++/96850] New: format missing from std

["michel at lebihan dot pl" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96850

            Bug ID: 96850
           Summary: format missing from std
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: michel at lebihan dot pl
  Target Milestone: ---

Hello,

std::format (https://en.cppreference.com/w/cpp/utility/format/format) was added
in C++20. When I try to compile the provided example:

```
#include <iostream>
#include <format>

int main() {
    std::cout << std::format("Hello {}!\n", "world");
}
```

I get the error:

```
g++ -std=c++20 main.cpp 
main.cpp:2:10: fatal error: format: No such file or directory
    2 | #include <format>
      |          ^~~~~~~~
compilation terminated.
```

It seems that this feature hasn't been implemented in gcc yet.