Here's a doc addition, regarding a problem with MSVC, for which Gnulib
cannot provide a workaround:
2023-11-04 Bruno Haible <br...@clisp.org>
fenv: Document an ABI break on MSVC.
* doc/posix-headers/fenv.texi: Document why fegetround and fesetround
are seemingly broken on MSVC.
diff --git a/doc/posix-headers/fenv.texi b/doc/posix-headers/fenv.texi
index 36c636d7db..25e306d579 100644
--- a/doc/posix-headers/fenv.texi
+++ b/doc/posix-headers/fenv.texi
@@ -14,4 +14,9 @@
Portability problems not fixed by Gnulib:
@itemize
+@item
+On MSVC, the values of the rounding direction macros have changed:
+@c https://github.com/MicrosoftDocs/cpp-docs/issues/4796
+In MSVC 14, @code{FE_UPWARD} is 0x100 and @code{FE_DOWNWARD} is 0x200,
+whereas in MSVC 14.30, it's the opposite.
@end itemize
