--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2010-12-19  Bruno Haible  <bruno@clisp.org>
+
+	Document some different function declarations on OSF/1 5.1.
+	* doc/posix-functions/gai_strerror.texi: Mention different declaration.
+	* doc/posix-functions/inet_ntop.texi: Likewise.
+	* doc/posix-functions/gethostname.texi: Likewise.
+	* lib/unistd.in.h (gethostname): Update comment.
+
 2010-12-19  Bruno Haible  <bruno@clisp.org>
 
 	doc: Mention vasprintf-posix module.

--- a/doc/posix-functions/gai_strerror.texi
+++ b/doc/posix-functions/gai_strerror.texi
@@ -15,4 +15,7 @@
 
 Portability problems not fixed by Gnulib:
 @itemize
+This function's return type is @code{char *} instead of @code{const char *}
+on some platforms:
+OSF/1 5.1.
 @end itemize

--- a/doc/posix-functions/gethostname.texi
+++ b/doc/posix-functions/gethostname.texi
@@ -16,6 +16,10 @@
 Portability problems not fixed by Gnulib:
 @itemize
 @item
+This function's second argument type is @code{int} instead of @code{size_t}
+on some platforms:
+OSF/1 5.1, Solaris 10.
+@item
 If the given buffer is too small for the host name, some implementations
 fail with @code{EINVAL}, instead of returning a truncated host name.
 @end itemize

--- a/doc/posix-functions/inet_ntop.texi
+++ b/doc/posix-functions/inet_ntop.texi
@@ -15,4 +15,8 @@
 
 Portability problems not fixed by Gnulib:
 @itemize
+@item
+This function's fourth argument type is @code{size_t} instead of
+@code{socklen_t} on some platforms:
+OSF/1 5.1.
 @end itemize

--- a/lib/unistd.in.h
+++ b/lib/unistd.in.h
@@ -654,7 +654,8 @@
 _GL_FUNCDECL_SYS (gethostname, int, (char *name, size_t len)
                                     _GL_ARG_NONNULL ((1)));
 #  endif
-/* Need to cast, because on Solaris 10 systems, the second parameter is
+/* Need to cast, because on Solaris 10 and OSF/1 5.1 systems, the second
+   parameter is
                                                       int len.  */
 _GL_CXXALIAS_SYS_CAST (gethostname, int, (char *name, size_t len));
 # endif