On Wednesday 26 March 2025 10:09:10 LIU Hao wrote:
> 在 2025-3-26 05:13, Pali Rohár 写道:
> > On Thursday 20 March 2025 20:38:57 Pali Rohár wrote:
> > > Hello, I started getting new compile warnings during compilation of
> > > mingw-w64 runtime.
> > >
> > > In file included from math/modfl.c:6:
> > > .../mingw-w64-headers/crt/fenv.h:64:39: warning: ‘__mingw_fe_dfl_env’
> > > initialized and declared ‘extern’
> > > extern const __MINGW_SELECTANY fenv_t __mingw_fe_dfl_env = { 0, 0 };
> > > ^~~~~~~~~~~~~~~~~~
> > > ... ...
> > > I think that it is related to commit 9c27617e016f ("headers: Use
> > > selectany fenv_t pointers for FE_*_ENV macros.").
> > >
> > > For me it looks really a bad idea to define a global variable in public
> > > header file with value and also with extern keyword.
> >
> > Hello, have you looked at this? I think that the "extern" keyword should
> > be removed here as it is not needed and also cause those gcc warnings.
> >
>
> In C++ `const` without `extern` or `volatile` implies internal linkage (same
> as `static const`) so `extern` is required. Maybe we can try splitting the
> definitions:
>
> extern const fenv_t __mingw_fe_dfl_env;
> const __MINGW_SELECTANY fenv_t __mingw_fe_dfl_env = { 0, 0 };
>
>
> This should have the same effect as a c++17 `constexpr inline` variable.
>
>
> --
> Best regards,
> LIU Hao
Thanks for looking at this. With your change, the warning is not emitted
during compiling of mingw-w64 (by C compiler). If it is fine, would you
commit your change?
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