[committed] Fix -Wmissing-attributes warning in libstdc++ (PR libstdc++/89402)

[Jonathan Wakely]

On 20/02/19 09:07 +0100, Jakub Jelinek wrote:
>Hi!
>
>The following patch fixes a warning when building on targets where long
>double switched from being the same as double to something wider,
>like e.g. powerpc*-linux, alpha*-linux, s390*-linux etc.
>
>Fixed thusly, bootstrapped/regtested on {x86_64,i686,s390x}-linux and
>bootstrapped on powerpc64le-linux, on both s390x and powerpc64le it removed
>all
>../../../../libstdc++-v3/src/c++98/compatibility-ldbl.cc:77:17: warning: 'void _ZNKSt4hashIeEclEe()' specifies less restrictive attribute than its target 'std::size_t std::tr1::hash<_Tp>::operator()(_Tp) const [with _Tp = long double]': 'pure' [-Wmissing-attributes]
>warnings from the build log.  Preapproved by Jonathan in the PR, committed
>to trunk.

Now I see:

/home/jwakely/src/gcc/libstdc++-v3/src/c++98/compatibility-ldbl.cc:78:65: warning: ‘pure’ attribute on function returning ‘void’ [-Wattributes]
   78 |   _GLIBCXX_PURE __attribute__((alias ("_ZNKSt3tr14hashIeEclEe")));
      |                                                                 ^

We can disable that with a diagnostic pragma.



>2019-02-20  Jakub Jelinek  <jakub@redhat.com>
>
>	PR libstdc++/89402
>	* src/c++98/compatibility-ldbl.cc (_ZNKSt4hashIeEclEe): Add
>	_GLIBCXX_PURE to the alias declaration.
>
>--- libstdc++-v3/src/c++98/compatibility-ldbl.cc.jj	2019-01-01 12:39:41.530606161 +0100
>+++ libstdc++-v3/src/c++98/compatibility-ldbl.cc	2019-02-19 16:12:52.402123217 +0100
>@@ -75,6 +75,6 @@ namespace std _GLIBCXX_VISIBILITY(defaul
> // and std::hash<long double>::operator()
> // are the same, no need to duplicate them.
> extern "C" void _ZNKSt4hashIeEclEe (void)
>-  __attribute__((alias ("_ZNKSt3tr14hashIeEclEe")));
>+  _GLIBCXX_PURE __attribute__((alias ("_ZNKSt3tr14hashIeEclEe")));
>
> #endif
>
>
>	Jakub