Re: static_string

From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2022-07-10 17:55:25

On Jul 10, 2022, at 9:25 AM, Gero Peterhoff via Boost <boost_at_[hidden]> wrote:
> 
> Hello,
> if i include <boost/static_string.hpp> i get errors in std::variant:
> 
> /usr/include/c++/12/variant:774:72: Fehler: Templateargument 4 ist ungültig
>  774 |                       void_t<decltype(_Arr<_Ti>{{std::declval<_Tp>()}})>>
>      |                                                                        ^~
> /usr/include/c++/12/variant:804:76: Fehler: Templateargument 3 ist ungültig
>  804 |     struct __accepted_index<_Tp, _Variant, void_t<_FUN_type<_Tp, _Variant>>>
>      |                                                                            ^
> 
> Can you retrace that?
> boost 1.79
> gcc 12.1 -std=gnu++2b
> openSuse Tumbleweed

I think we need more information.
How about a complete, self-contained program?

I tried compiling this:

```
#include <boost/static_string.hpp>
#include <variant>

int main () {}
```

On godbolt, using “x86_64 g++ 12.1”  with options "-std=gnu++2b -I/opt/compiler-explorer/libs/boost_1_79_0”

And while I got a warning about `unary_function`, I got no errors.

In file included from /opt/compiler-explorer/libs/boost_1_79_0/boost/static_string/config.hpp:151,
                 from /opt/compiler-explorer/libs/boost_1_79_0/boost/static_string/static_string.hpp:16,
                 from /opt/compiler-explorer/libs/boost_1_79_0/boost/static_string.hpp:12,
                 from <source>:1:
/opt/compiler-explorer/libs/boost_1_79_0/boost/container_hash/hash.hpp:132:33: warning: 'template<class _Arg, class _Result> struct std::unary_function' is deprecated [-Wdeprecated-declarations]
  132 |         struct hash_base : std::unary_function<T, std::size_t> {};
      |                                 ^~~~~~~~~~~~~~
In file included from /opt/compiler-explorer/gcc-12.1.0/include/c++/12.1.0/functional:49,
                 from /opt/compiler-explorer/libs/boost_1_79_0/boost/container_hash/hash.hpp:20:
/opt/compiler-explorer/gcc-12.1.0/include/c++/12.1.0/bits/stl_function.h:117:12: note: declared here
  117 |     struct unary_function
      |            ^~~~~~~~~~~~~~
Compiler returned: 0

— Marshall