Re: [PATCH] libstdc++-v3 testsuite: Call fesetround(FE_DOWNWARD) only if defined

[Jonathan Wakely <jwakely@redhat.com>]

On Tue, 22 Mar 2022 at 15:48, Hans-Peter Nilsson via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> Ok to commit?

OK, thanks.


>
> ----- 8< -----
>
> Without this, for a typical soft-float target such as cris-elf, after
> commit r12-7676-g5a4e208022e704 you'll see, in libstdc++.log:
> ...
> FAIL: 20_util/from_chars/6.cc (test for excess errors)
> Excess errors:
> /home/hp/tmp/auto0321/gcc/libstdc++-v3/testsuite/20_util/from_chars/6.cc:33: error: 'FE_DOWNWARD' was not declared in this scope
>
> UNRESOLVED: 20_util/from_chars/6.cc compilation failed to produce executable
> ...
>
> It appears to be a side-effect of that commit changing the
> way __cpp_lib_to_chars is defined.  (On the bright side,
> ./7.cc now passes since that commit.)
>
> TFM, specifically fenv(3), says that "Each of the macros
> FE_DIVBYZERO, FE_INEXACT, FE_INVALID, FE_OVERFLOW,
> FE_UNDERFLOW is defined when the implementation supports
> handling of the corresponding exception".
>
> A git-grep shows that this was the only place using a FE_ macro
> unconditionally.
>
> libstdc++-v3:
>         * testsuite/20_util/from_chars/6.cc (test01) [FE_DOWNWARD]:
>         Conditionalize call to fesetround.
>
> diff --git a/libstdc++-v3/testsuite/20_util/from_chars/6.cc b/libstdc++-v3/testsuite/20_util/from_chars/6.cc
> index d33484cebfee..fff3450b56c9 100644
> --- a/libstdc++-v3/testsuite/20_util/from_chars/6.cc
> +++ b/libstdc++-v3/testsuite/20_util/from_chars/6.cc
> @@ -30,7 +30,9 @@ test01()
>  #if __cpp_lib_to_chars >= 201611L
>  #if _GLIBCXX_USE_C99_FENV_TR1
>    double d;
> +#ifdef FE_DOWNWARD
>    std::fesetround(FE_DOWNWARD);
> +#endif
>    const std::string s = "0.099999999999999999999999999";
>    auto res = std::from_chars(s.data(), s.data() + s.length(), d);
>    VERIFY( res.ec == std::errc{} );
> --
> 2.30.2
>