[committed] libstdc++: Add comment about memalign requirements

[Jonathan Wakely <jwakely@redhat.com>]

Pushed to trunk.

-- >8 --

The memalign man page on Solaris and QNX lists an additional requirement
for the alignment value that is not present in all implementation of
that non-standard function. For both those targets we should actually be
using posix_memalign anyway, so it doesn't matter. This just adds a
comment making note of that fact.

libstdc++-v3/ChangeLog:

	* libsupc++/new_opa.cc (aligned_alloc): Add comment.
---
 libstdc++-v3/libsupc++/new_opa.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libstdc++-v3/libsupc++/new_opa.cc b/libstdc++-v3/libsupc++/new_opa.cc
index 5f24737de1c..411cd8d98b2 100644
--- a/libstdc++-v3/libsupc++/new_opa.cc
+++ b/libstdc++-v3/libsupc++/new_opa.cc
@@ -87,6 +87,8 @@ aligned_alloc (std::size_t al, std::size_t sz)
 static inline void*
 aligned_alloc (std::size_t al, std::size_t sz)
 {
+  // Solaris requires al >= sizeof a word and QNX requires >= sizeof(void*)
+  // but they both provide posix_memalign, so will use the definition above.
   return memalign (al, sz);
 }
 #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN
-- 
2.34.1