[Bug c++/118834] New: __is_same diagnostic can be more specific

[egor.pugin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118834

            Bug ID: 118834
           Summary: __is_same diagnostic can be more specific
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: egor.pugin at gmail dot com
  Target Milestone: ---

Consider https://godbolt.org/z/rEvo8v88P

===

#include <cstdint>
#include <string>

static_assert(__is_same(std::int64_t,
    decltype(std::stoll(std::string{}))));

static_assert(__is_same(long,
    long long));

static_assert(std::same_as<std::int64_t,
    decltype(std::stoll(std::string{}))>);

===

Gcc gives 

<source>:4:15: error: static assertion failed

where clang says

<source>:4:15: error: static assertion failed due to requirement
'__is_same(long, long long)'