[gcc r14-389] ibstdc++: Shut up -Wattribute-alias warning [PR109694]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:87de39e4c3686535728f3a347f772e73af4cf262

commit r14-389-g87de39e4c3686535728f3a347f772e73af4cf262
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 2 10:58:19 2023 +0200

    ibstdc++: Shut up -Wattribute-alias warning [PR109694]
    
    I've followed what other files do, using attribute alias with not really
    matching function type (after all, it isn't really possible when it is a
    constructor), but seems I've missed it warns:
    ../../../../../libstdc++-v3/src/c++98/ios_init.cc:203:8: warning: ‘void std::ios_base_library_init()’ alias between functions of incompatible types ‘void()’ and ‘void
    +(std::ios_base::Init::)()’ [-Wattribute-alias=]
      203 |   void ios_base_library_init (void)
          |        ^~~~~~~~~~~~~~~~~~~~~
    ../../../../../libstdc++-v3/src/c++98/ios_init.cc:78:3: note: aliased declaration here
       78 |   ios_base::Init::Init()
          |   ^~~~~~~~
    The PR talks about clang++ warning there (which I think isn't really
    supported, libstdc++ sources ought to be built by GCC), but it warns
    when built with GCC too.
    
    The following patch fixes it by doing what other libstdc++ sources do in
    those cases.
    
    2023-05-02  Jakub Jelinek  <jakub@redhat.com>
    
            PR libstdc++/109694
            * src/c++98/ios_init.cc: Add #pragma GCC diagnostic ignored for
            -Wattribute-alias.

Diff:
---
 libstdc++-v3/src/c++98/ios_init.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libstdc++-v3/src/c++98/ios_init.cc b/libstdc++-v3/src/c++98/ios_init.cc
index 0c2ba945f36..ace94b992b5 100644
--- a/libstdc++-v3/src/c++98/ios_init.cc
+++ b/libstdc++-v3/src/c++98/ios_init.cc
@@ -200,6 +200,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   }
 
 #ifdef _GLIBCXX_SYMVER_GNU
+#pragma GCC diagnostic ignored "-Wattribute-alias"
+
   void ios_base_library_init (void)
   __attribute__((alias ("_ZNSt8ios_base4InitC1Ev")));
 #endif