Re: [PATCH] libstdc++: Shut up -Wattribute-alias warning [PR109694]

[Jonathan Wakely <jwakely@redhat.com>]

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On Tue, 2 May 2023 at 09:42, Jakub Jelinek wrote:

> Hi!
>
> 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.
>
> Tested on x86_64-linux, ok for trunk and later 13.2?
>

OK, thanks.


>
> 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.
>
> --- libstdc++-v3/src/c++98/ios_init.cc.jj       2023-04-28
> 10:49:22.105352644 +0200
> +++ libstdc++-v3/src/c++98/ios_init.cc  2023-05-02 10:24:09.073741162 +0200
> @@ -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
>
>         Jakub
>
>