[PATCH] libstdc++: Guard use of float16_t and bfloat16_t

[Jonathan Wakely]

OK, thanks

(You'll need to add the PR number to the first line to get past the hooks)

On Sat, 4 Apr 2026, 09:35 Matthias Kretz, <MatthiasKretz@gmx.net> wrote:

> The rest of this test is still relevant, thus only the (b)float16_t
> tests are made optional rather than skipping the whole test via
> dg-effective-target.
>
> libstdc++-v3/ChangeLog:
>
>         PR libstdc++/124722
>         * testsuite/std/simd/traits_impl.cc: Add __STDCPP_FLOAT16_T__
>           and __STDCPP_BFLOAT16_T__ guards.
>
> Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
> ---
>  libstdc++-v3/testsuite/std/simd/traits_impl.cc | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/libstdc++-v3/testsuite/std/simd/traits_impl.cc b/libstdc++-v3/
> testsuite/std/simd/traits_impl.cc
> index a264bd5f140..06bf6d5be25 100644
> --- a/libstdc++-v3/testsuite/std/simd/traits_impl.cc
> +++ b/libstdc++-v3/testsuite/std/simd/traits_impl.cc
> @@ -9,7 +9,9 @@
>
>  namespace simd = std::simd;
>
> +#ifdef __STDCPP_FLOAT16_T__
>  using std::float16_t;
> +#endif
>  using std::float32_t;
>  using std::float64_t;
>
> @@ -17,7 +19,11 @@ namespace simd
>
>  void test()
>  {
> -  template for (auto t : {float(), double(), float16_t(), float32_t(),
> float64_t()})
> +  template for (auto t : {float(), double(),
> +#ifdef __STDCPP_FLOAT16_T__
> +                         float16_t(),
> +#endif
> +                         float32_t(), float64_t()})
>      {
>        using T = decltype(t);
>        static_assert(__vectorizable<T>);
> @@ -25,7 +31,9 @@ namespace simd
>
>    static_assert(!__vectorizable<const float>);
>    static_assert(!__vectorizable<float&>);
> +#ifdef __STDCPP_BFLOAT16_T__
>    static_assert(!__vectorizable<std::bfloat16_t>);
> +#endif
>
>    template for (constexpr int N : {1, 2, 4, 8})
>      {
> @@ -82,8 +90,10 @@ namespace simd
>    static_assert( __value_preserving_convertible_to<float, double>);
>    static_assert(!__value_preserving_convertible_to<double, float>);
>
> +#ifdef __STDCPP_FLOAT16_T__
>    static_assert(__explicitly_convertible_to<float, float16_t>);
>    static_assert(__explicitly_convertible_to<long, float16_t>);
> +#endif
>
>    static_assert(__constexpr_wrapper_like<std::constant_wrapper<2>>);
>    static_assert(__constexpr_wrapper_like<std::integral_constant<int, 1>>);
> @@ -95,7 +105,9 @@ namespace simd
>    static_assert(!__broadcast_constructible<const int, float>);
>
>    static_assert(__broadcast_constructible<decltype(std::cw<2>), float>);
> +#ifdef __STDCPP_FLOAT16_T__
>    static_assert(__broadcast_constructible<decltype(std::cw<0.f>),
> std::float16_t>);
> +#endif
>
>
>    static_assert(__higher_rank_than<long, int>);
> @@ -112,7 +124,9 @@ namespace simd
>    static_assert(__higher_rank_than<unsigned long, int>);
>    static_assert(__higher_rank_than<unsigned long long, long>);
>
> +#ifdef __STDCPP_FLOAT16_T__
>    static_assert(__higher_rank_than<float, float16_t>);
> +#endif
>    static_assert(__higher_rank_than<float32_t, float>);
>    static_assert(__higher_rank_than<double, float32_t>);
>    static_assert(__higher_rank_than<double, float>);
> --
> ──────────────────────────────────────────────────────────────────────────
>  Dr. Matthias Kretz                           https://mattkretz.github.io
>  GSI Helmholtz Center for Heavy Ion Research               https://gsi.de
>  std::simd
> ──────────────────────────────────────────────────────────────────────────
>
>
>
>
>
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