1 files changed, 12 insertions, 33 deletions

diff --git a/gl/m4/threadlib.m4 b/gl/m4/threadlib.m4
index 333c8fe0..bdea4b97 100644
--- a/gl/m4/threadlib.m4
+++ b/gl/m4/threadlib.m4
@@ -1,6 +1,6 @@
 # threadlib.m4
-# serial 45.1
-dnl Copyright (C) 2005-2025 Free Software Foundation, Inc.
+# serial 49
+dnl Copyright (C) 2005-2026 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -57,16 +57,6 @@ AC_DEFUN([gl_ANYTHREADLIB_EARLY],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
   if test -z "$gl_anythreadlib_early_done"; then
-    AS_CASE([$host_os],
-      [osf*],
-       [# On OSF/1, the compiler needs the flag -D_REENTRANT so that it
-        # groks <pthread.h>. cc also understands the flag -pthread, but
-        # we do not use it because 1. gcc-2.95 does not understand -pthread,
-        # 2. putting a flag into CPPFLAGS that has an effect on the linker
-        # causes the AC_LINK_IFELSE test below to succeed unexpectedly,
-        # leading to wrong values of LIBTHREAD and LTLIBTHREAD.
-        CPPFLAGS="$CPPFLAGS -D_REENTRANT"
-       ])
     # Some systems optimize for single-threaded programs by default, and
     # need special flags to disable these optimizations. For example, the
     # definition of errno in <errno.h>.
@@ -190,17 +180,13 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
     gl_pthread_api=no
     LIBPTHREAD=
     LIBPMULTITHREAD=
-    # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
-    # it groks <pthread.h>. It is added above, in gl_ANYTHREADLIB_EARLY.
     AC_CHECK_HEADER([pthread.h],
       [gl_have_pthread_h=yes], [gl_have_pthread_h=no])
     AS_IF([test "$gl_have_pthread_h" = yes], [
       # Other possible tests:
       #   -lpthreads (FSU threads, PCthreads)
       #   -lgthreads
-      # Test whether both pthread_mutex_lock and pthread_mutexattr_init exist
-      # in libc. IRIX 6.5 has the first one in both libc and libpthread, but
-      # the second one only in libpthread, and lock.c needs it.
+      # Test whether both pthread_mutex_lock exists in libc.
       #
       # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
       # needs -pthread for some reason.  See:
@@ -212,10 +198,8 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
           [AC_LANG_PROGRAM(
              [[#include <pthread.h>
                pthread_mutex_t m;
-               pthread_mutexattr_t ma;
              ]],
-             [[pthread_mutex_lock (&m);
-               pthread_mutexattr_init (&ma);]])],
+             [[pthread_mutex_lock (&m);]])],
           [gl_pthread_api=yes
            LIBPTHREAD=$gl_pthread
            LIBPMULTITHREAD=$gl_pthread])
@@ -244,8 +228,7 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
          ])
       echo "$as_me:__oline__: gl_pthread_in_glibc=$gl_pthread_in_glibc" >&AS_MESSAGE_LOG_FD
 
-      # Test for libpthread by looking for pthread_kill. (Not pthread_self,
-      # since it is defined as a macro on OSF/1.)
+      # Test for libpthread by looking for pthread_kill.
       AS_IF([test $gl_pthread_api = yes && test -z "$LIBPTHREAD"], [
         # The program links fine without libpthread. But it may actually
         # need to link with libpthread in order to create multiple threads.
@@ -451,18 +434,19 @@ AC_DEFUN([gl_THREADLIB_EARLY_BODY],
   dnl gl_use_winpthreads_default defaults to "no", because in mingw 10, like
   dnl in mingw 5, the use of libwinpthread still makes test-pthread-tss crash.
   m4_divert_text([DEFAULTS], [gl_use_winpthreads_default=no])
+  dnl Don't display the --disable-threads option
+  dnl   - if the package builds one or more libraries, because libraries must
+  dnl     always be multithread-safe (as far as possible),
+  dnl   - if the package defines gl_THREADLIB_DEFAULT_NO, because the option
+  dnl     would then be a no-op.
   AC_ARG_ENABLE([threads],
-AS_HELP_STRING([[--enable-threads={isoc|posix|isoc+posix|windows}]], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
-AS_HELP_STRING([[--disable-threads]], [build without multithread safety])]),
+AS_HELP_STRING([[--enable-threads={isoc|posix|isoc+posix|windows}]], [specify multithreading API])m4_ifdef([LT_INIT], [], [m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
+AS_HELP_STRING([[--disable-threads]], [build without multithread safety])])]),
     [gl_use_threads=$enableval],
     [if test -n "$gl_use_threads_default"; then
        gl_use_threads="$gl_use_threads_default"
      else
        AS_CASE([$host_os],
-         dnl Disable multithreading by default on OSF/1, because it interferes
-         dnl with fork()/exec(): When msgexec is linked with -lpthread, its
-         dnl child process gets an endless segmentation fault inside execvp().
-         [osf*], [gl_use_threads=no],
          dnl Disable multithreading by default on Cygwin 1.5.x, because it has
          dnl bugs that lead to endless loops or crashes. See
          dnl <https://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
@@ -665,13 +649,8 @@ dnl
 dnl HP-UX 11           posix      -lpthread       N (cc) OK
 dnl                                               Y (gcc)
 dnl
-dnl IRIX 6.5           posix      -lpthread       Y      0.5
-dnl
 dnl AIX 4.3,5.1        posix      -lpthread       N      AIX 4: 0.5; AIX 5: OK
 dnl
-dnl OSF/1 4.0,5.1      posix      -pthread (cc)   N      OK
-dnl                               -lpthread (gcc) Y
-dnl
 dnl Cygwin             posix      -lpthread       Y      OK
 dnl
 dnl Mingw              windows                    N      OK