[committed v2] libstdc++: Fix required alignment computation for floating points [PR122267]

[Tomasz Kamiński]

Before the r16-4349-g90dde804626f13 the required alignment of floating point,
and pointer specialization used __alignof__(_Vt) as required_alignment, and
mentioned commit changed them to alignof(_Vt). This values differs on i686
for double, as alignof(double) is 4, and __alignof__(double) is 8.

This patch restores the previous behavior.

	PR libstdc++/122267

libstdc++-v3/ChangeLog:

	* include/bits/atomic_base.h
	(__atomic_ref_base<const _Tp>::_S_required_alignment):
	Use __alignof__	instead of alignof.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
---
v2 fixes spelling of alignment in commit message.
Pushed to trunk.

 libstdc++-v3/include/bits/atomic_base.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/bits/atomic_base.h b/libstdc++-v3/include/bits/atomic_base.h
index 0f3f6b1925d..7e4ad2b1272 100644
--- a/libstdc++-v3/include/bits/atomic_base.h
+++ b/libstdc++-v3/include/bits/atomic_base.h
@@ -1538,7 +1538,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _S_required_aligment()
       {
 	if constexpr (is_floating_point_v<_Vt> || is_pointer_v<_Vt>)
-	  return alignof(_Vt);
+	  return __alignof__(_Vt);
 	else if constexpr ((sizeof(_Vt) & (sizeof(_Vt) - 1)) || sizeof(_Vt) > 16)
 	  return alignof(_Vt);
 	else
-- 
2.51.0