[gcc r13-6811] libstdc++: Remove std::formatter<const charT[N], charT> specialization

[Jonathan Wakely]

https://gcc.gnu.org/g:f2e70da638b4f6ba868ff07ab2123cad4fd9fd02

commit r13-6811-gf2e70da638b4f6ba868ff07ab2123cad4fd9fd02
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Mar 22 13:01:07 2023 +0000

    libstdc++: Remove std::formatter<const charT[N], charT> specialization
    
    This was approved in Issaquah as LWG 3833.
    
    libstdc++-v3/ChangeLog:
    
            * include/std/format (formatter<const charT[N], charT>): Do not
            define partial speclialization, as per LWG 3833.
            * testsuite/std/format/formatter/requirements.cc: Check it.

Diff:
---
 libstdc++-v3/include/std/format                    | 22 ----------------------
 .../testsuite/std/format/formatter/requirements.cc |  9 +++++++++
 2 files changed, 9 insertions(+), 22 deletions(-)

diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 0e40bce5c15..72b6b450ad1 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -1882,28 +1882,6 @@ namespace __format
       __format::__formatter_str<_CharT> _M_f;
     };
 
-  template<__format::__char _CharT, size_t _Nm>
-    struct formatter<const _CharT[_Nm], _CharT>
-    {
-      formatter() = default;
-
-      [[__gnu__::__always_inline__]]
-      constexpr typename basic_format_parse_context<_CharT>::iterator
-      parse(basic_format_parse_context<_CharT>& __pc)
-      { return _M_f.parse(__pc); }
-
-      template<typename _Out>
-	typename basic_format_context<_Out, _CharT>::iterator
-	format(const _CharT (&__u)[_Nm],
-	       basic_format_context<_Out, _CharT>& __fc) const
-	{ return _M_f.format({__u, _Nm}, __fc); }
-
-      constexpr void set_debug_format() noexcept { _M_f.set_debug_format(); }
-
-    private:
-      __format::__formatter_str<_CharT> _M_f;
-    };
-
   template<typename _Traits, typename _Alloc>
     struct formatter<basic_string<char, _Traits, _Alloc>, char>
     {
diff --git a/libstdc++-v3/testsuite/std/format/formatter/requirements.cc b/libstdc++-v3/testsuite/std/format/formatter/requirements.cc
index 3bff8bdbd5d..7d95f7fafe9 100644
--- a/libstdc++-v3/testsuite/std/format/formatter/requirements.cc
+++ b/libstdc++-v3/testsuite/std/format/formatter/requirements.cc
@@ -51,6 +51,15 @@ test_specializations() // [format.formatter.spec]
   static_assert( ! std::is_move_constructible_v<Ferr> );
   static_assert( ! std::is_copy_assignable_v<Ferr> );
   static_assert( ! std::is_move_assignable_v<Ferr> );
+
+  // LWG 3833. Remove specialization
+  // template<size_t N> struct formatter<const charT[N], charT>
+  using Farr = std::format_context::formatter_type<const char[1]>;
+  static_assert( ! std::is_default_constructible_v<Farr> );
+  static_assert( ! std::is_copy_constructible_v<Farr> );
+  static_assert( ! std::is_move_constructible_v<Farr> );
+  static_assert( ! std::is_copy_assignable_v<Farr> );
+  static_assert( ! std::is_move_assignable_v<Farr> );
 }
 
 int main()