[PATCH] libstdc++: Add [[nodiscard]] to std::byteswap

[Jakub Jelinek]

Hi!

This patch adds [[nodiscard]] to std::byteswap, because the function
template doesn't do anything useful if the result isn't used.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2021-11-30  Jakub Jelinek  <jakub@redhat.com>

	* include/std/bit (byteswap): Add [[nodiscard]].

--- libstdc++-v3/include/std/bit.jj	2021-11-28 16:32:15.204524854 +0100
+++ libstdc++-v3/include/std/bit	2021-11-29 17:40:00.781074520 +0100
@@ -83,6 +83,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /// Reverse order of bytes in the object representation of `value`.
   template<typename _Tp>
+    [[nodiscard]]
     constexpr enable_if_t<is_integral<_Tp>::value, _Tp>
     byteswap(_Tp __value) noexcept
     {

	Jakub