[Bug c++/126514] New: GCC rejects valid out-of-class static data member definition with auto

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126514

            Bug ID: 126514
           Summary: GCC rejects valid out-of-class static data member
                    definition with auto
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: attackerj1113 at gmail dot com
  Target Milestone: ---

The following code is rejected by GCC, but accepted by Clang, MSVC, and EDG:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
struct S
{
  static int b;
};

auto S::b = 4;

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
https://godbolt.org/z/vYjv3q93e

Output:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:6:6: error: conflicting declaration 'auto S::b'
    6 | auto S::b = 4;
      |      ^
<source>:3:14: note: previous declaration as 'int S::b'
    3 |   static int b;
      |              ^
Compiler returned: 1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GCC rejects auto S::b = 4; when S::b was previously declared as static int b;.
Replacing auto with int is accepted. 

As I understand it, auto here is deduced as int, so the two declarations would
appear to be consistent — though I may be missing something, and would
appreciate clarification.