* doc/posix-headers/time.texi: Mention issues with tm_gmtoff,
tm_zone, tzname, etc.
---
doc/posix-headers/time.texi | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/doc/posix-headers/time.texi b/doc/posix-headers/time.texi
index e7304cbd1a..26587d4c6a 100644
--- a/doc/posix-headers/time.texi
+++ b/doc/posix-headers/time.texi
@@ -30,7 +30,22 @@ glibc 2.34+ atop 32-bit x86 or ARM Linux.
@end itemize
Portability problems not fixed by Gnulib:
+
@itemize
+@item
+On some platforms @code{struct tm} lacks the the @code{tm_gmtoff} and
+@code{tm_zone} members:
+AIX 7.3, HP-UX 11, Solaris 11.4, mingw, MSVC 14.
+
+@item
+On some platforms the global state variables @code{daylight},
+@code{timezone} and @code{tzname} are not available. Even on
+platforms where they are available, their contents are often unreliable,
+even in single-threaded programs.
+Portable code can instead use @code{struct tm}'s @code{tm_gmtoff} and
+@code{tm_zone} members when available, and the @code{strftime} function
+with @code{%z} or @code{%Z} conversion specifiers otherwise.
+
@item
On platforms where @code{time_t} is always 32-bit, functions like
@code{stat} can fail with @code{errno == EOVERFLOW} when a timestamp
--
2.43.0
