thread, lock, cond, tls: Remove support for old Solaris threads.

Solaris >= 2.5.1 has POSIX threads.

* m4/threadlib.m4 (gl_THREADLIB_EARLY_BODY): Don't document
--enable-threads=solaris any more.
(gl_THREADLIB_BODY): Don't set USE_SOLARIS_THREADS any more.
* lib/glthread/thread.c: Update comment.
* lib/glthread/thread.h: Remove code for USE_SOLARIS_THREADS.
* lib/glthread/lock.h: Likewise.
* lib/glthread/lock.c: Likewise.
* lib/glthread/cond.h: Likewise.
* lib/glthread/cond.c: Likewise.
* lib/glthread/tls.h: Likewise.
* lib/glthread/tls.c: Likewise.
* lib/glthread/yield.h: Likewise.
* lib/regex_internal.h: Likewise.
* tests/test-thread_create.c: Likewise.
* tests/test-lock.c: Likewise.
* tests/test-cond.c: Likewise.
* tests/test-tls.c: Likewise.

16 files changed, 43 insertions, 538 deletions

diff --git a/ChangeLog b/ChangeLog
index 98d5531b1c..f6f9b3848d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,27 @@
 2019-07-05  Bruno Haible  <bruno@clisp.org>
 
+	thread, lock, cond, tls: Remove support for old Solaris threads.
+	Solaris >= 2.5.1 has POSIX threads.
+	* m4/threadlib.m4 (gl_THREADLIB_EARLY_BODY): Don't document
+	--enable-threads=solaris any more.
+	(gl_THREADLIB_BODY): Don't set USE_SOLARIS_THREADS any more.
+	* lib/glthread/thread.c: Update comment.
+	* lib/glthread/thread.h: Remove code for USE_SOLARIS_THREADS.
+	* lib/glthread/lock.h: Likewise.
+	* lib/glthread/lock.c: Likewise.
+	* lib/glthread/cond.h: Likewise.
+	* lib/glthread/cond.c: Likewise.
+	* lib/glthread/tls.h: Likewise.
+	* lib/glthread/tls.c: Likewise.
+	* lib/glthread/yield.h: Likewise.
+	* lib/regex_internal.h: Likewise.
+	* tests/test-thread_create.c: Likewise.
+	* tests/test-lock.c: Likewise.
+	* tests/test-cond.c: Likewise.
+	* tests/test-tls.c: Likewise.
+
+2019-07-05  Bruno Haible  <bruno@clisp.org>
+
 	getcwd-lgpl, getcwd: Don't call realloc when it is pointless.
 	* lib/getcwd-lgpl.c (rpl_getcwd): Don't call realloc if the result's
 	needed size is equal to the allocated size.
diff --git a/lib/glthread/cond.c b/lib/glthread/cond.c
index 2285c16520..72aeca4a32 100644
--- a/lib/glthread/cond.c
+++ b/lib/glthread/cond.c
@@ -52,27 +52,6 @@ glthread_cond_timedwait_multithreaded (gl_cond_t *cond,
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* -------------------------- gl_cond_t datatype -------------------------- */
-
-int
-glthread_cond_timedwait_multithreaded (gl_cond_t *cond,
-                                       gl_lock_t *lock,
-                                       struct timespec *abstime)
-{
-  int ret;
-
-  ret = cond_timedwait (cond, lock, abstime);
-  if (ret == ETIME)
-    return ETIMEDOUT;
-  return ret;
-}
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 #endif
diff --git a/lib/glthread/cond.h b/lib/glthread/cond.h
index 8880b078e8..b03ffe300c 100644
--- a/lib/glthread/cond.h
+++ b/lib/glthread/cond.h
@@ -56,7 +56,7 @@
 #include "glthread/lock.h"
 
 #if !defined c11_threads_in_use
-# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK || USE_SOLARIS_THREADS_WEAK)
+# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK)
 #  include <threads.h>
 #  pragma weak thrd_exit
 #  define c11_threads_in_use() (thrd_exit != NULL)
@@ -227,67 +227,6 @@ extern int glthread_cond_timedwait_multithreaded (gl_cond_t *cond, gl_lock_t *lo
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* Use the old Solaris threads library.  */
-
-# include <thread.h>
-# include <synch.h>
-
-# ifdef __cplusplus
-extern "C" {
-# endif
-
-# if USE_SOLARIS_THREADS_WEAK
-
-/* Use weak references to the old Solaris threads library.  */
-
-#  pragma weak cond_init
-#  pragma weak cond_wait
-#  pragma weak cond_timedwait
-#  pragma weak cond_signal
-#  pragma weak cond_broadcast
-#  pragma weak cond_destroy
-#  pragma weak thr_suspend
-#  define thread_in_use() (thr_suspend != NULL || c11_threads_in_use ())
-
-# else
-
-#  define thread_in_use() 1
-
-# endif
-
-/* -------------------------- gl_cond_t datatype -------------------------- */
-
-typedef cond_t gl_cond_t;
-# define gl_cond_define(STORAGECLASS, NAME) \
-    STORAGECLASS gl_cond_t NAME;
-# define gl_cond_define_initialized(STORAGECLASS, NAME) \
-    STORAGECLASS gl_cond_t NAME = gl_cond_initializer;
-# define gl_cond_initializer \
-    DEFAULTCV
-# define glthread_cond_init(COND) \
-    (pthread_in_use () ? cond_init (COND, USYNC_THREAD, NULL) : 0)
-# define glthread_cond_wait(COND, LOCK) \
-    (pthread_in_use () ? cond_wait (COND, LOCK) : 0)
-# define glthread_cond_timedwait(COND, LOCK, ABSTIME) \
-    (pthread_in_use () ? glthread_cond_timedwait_multithreaded (COND, LOCK, ABSTIME) : 0)
-# define glthread_cond_signal(COND) \
-    (pthread_in_use () ? cond_signal (COND) : 0)
-# define glthread_cond_broadcast(COND) \
-    (pthread_in_use () ? cond_broadcast (COND) : 0)
-# define glthread_cond_destroy(COND) \
-    (pthread_in_use () ? cond_destroy (COND) : 0)
-extern int glthread_cond_timedwait_multithreaded (gl_cond_t *cond, gl_lock_t *lock, struct timespec *abstime);
-
-# ifdef __cplusplus
-}
-# endif
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
@@ -334,7 +273,7 @@ typedef glwthread_cond_t gl_cond_t;
 
 /* ========================================================================= */
 
-#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WINDOWS_THREADS)
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS)
 
 /* Provide dummy implementation if threads are not supported.  */
 
diff --git a/lib/glthread/lock.c b/lib/glthread/lock.c
index a686a306d6..e7fa3f8961 100644
--- a/lib/glthread/lock.c
+++ b/lib/glthread/lock.c
@@ -15,8 +15,7 @@
    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
 
 /* Written by Bruno Haible <bruno@clisp.org>, 2005.
-   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
-   gthr-win32.h.  */
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-win32.h.  */
 
 #include <config.h>
 
@@ -680,117 +679,6 @@ glthread_once_singlethreaded (pth_once_t *once_control)
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* Use the old Solaris threads library.  */
-
-/* -------------------------- gl_lock_t datatype -------------------------- */
-
-/* ------------------------- gl_rwlock_t datatype ------------------------- */
-
-/* --------------------- gl_recursive_lock_t datatype --------------------- */
-
-int
-glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
-{
-  int err;
-
-  err = mutex_init (&lock->mutex, USYNC_THREAD, NULL);
-  if (err != 0)
-    return err;
-  lock->owner = (thread_t) 0;
-  lock->depth = 0;
-  return 0;
-}
-
-int
-glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
-{
-  thread_t self = thr_self ();
-  if (lock->owner != self)
-    {
-      int err;
-
-      err = mutex_lock (&lock->mutex);
-      if (err != 0)
-        return err;
-      lock->owner = self;
-    }
-  if (++(lock->depth) == 0) /* wraparound? */
-    {
-      lock->depth--;
-      return EAGAIN;
-    }
-  return 0;
-}
-
-int
-glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock)
-{
-  if (lock->owner != thr_self ())
-    return EPERM;
-  if (lock->depth == 0)
-    return EINVAL;
-  if (--(lock->depth) == 0)
-    {
-      lock->owner = (thread_t) 0;
-      return mutex_unlock (&lock->mutex);
-    }
-  else
-    return 0;
-}
-
-int
-glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
-{
-  if (lock->owner != (thread_t) 0)
-    return EBUSY;
-  return mutex_destroy (&lock->mutex);
-}
-
-/* -------------------------- gl_once_t datatype -------------------------- */
-
-int
-glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void))
-{
-  if (!once_control->inited)
-    {
-      int err;
-
-      /* Use the mutex to guarantee that if another thread is already calling
-         the initfunction, this thread waits until it's finished.  */
-      err = mutex_lock (&once_control->mutex);
-      if (err != 0)
-        return err;
-      if (!once_control->inited)
-        {
-          once_control->inited = 1;
-          initfunction ();
-        }
-      return mutex_unlock (&once_control->mutex);
-    }
-  else
-    return 0;
-}
-
-int
-glthread_once_singlethreaded (gl_once_t *once_control)
-{
-  /* We know that gl_once_t contains an integer type.  */
-  if (!once_control->inited)
-    {
-      /* First time use of once_control.  Invert the marker.  */
-      once_control->inited = ~ 0;
-      return 1;
-    }
-  else
-    return 0;
-}
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 /* ------------------------- gl_rwlock_t datatype ------------------------- */
diff --git a/lib/glthread/lock.h b/lib/glthread/lock.h
index fb1ebc6362..2db8b7ecab 100644
--- a/lib/glthread/lock.h
+++ b/lib/glthread/lock.h
@@ -15,8 +15,7 @@
    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
 
 /* Written by Bruno Haible <bruno@clisp.org>, 2005.
-   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
-   gthr-win32.h.  */
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-win32.h.  */
 
 /* This file contains locking primitives for use with a given thread library.
    It does not contain primitives for creating threads or for other
@@ -82,7 +81,7 @@
 #include <stdlib.h>
 
 #if !defined c11_threads_in_use
-# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK || USE_SOLARIS_THREADS_WEAK)
+# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK)
 #  include <threads.h>
 #  pragma weak thrd_exit
 #  define c11_threads_in_use() (thrd_exit != NULL)
@@ -556,135 +555,6 @@ extern int glthread_once_singlethreaded (pth_once_t *once_control);
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* Use the old Solaris threads library.  */
-
-# include <thread.h>
-# include <synch.h>
-
-# ifdef __cplusplus
-extern "C" {
-# endif
-
-# if USE_SOLARIS_THREADS_WEAK
-
-/* Use weak references to the old Solaris threads library.  */
-
-#  pragma weak mutex_init
-#  pragma weak mutex_lock
-#  pragma weak mutex_unlock
-#  pragma weak mutex_destroy
-#  pragma weak rwlock_init
-#  pragma weak rw_rdlock
-#  pragma weak rw_wrlock
-#  pragma weak rw_unlock
-#  pragma weak rwlock_destroy
-#  pragma weak thr_self
-
-#  pragma weak thr_suspend
-#  define thread_in_use() (thr_suspend != NULL || c11_threads_in_use ())
-
-# else
-
-#  define thread_in_use() 1
-
-# endif
-
-/* -------------------------- gl_lock_t datatype -------------------------- */
-
-typedef mutex_t gl_lock_t;
-# define gl_lock_define(STORAGECLASS, NAME) \
-    STORAGECLASS mutex_t NAME;
-# define gl_lock_define_initialized(STORAGECLASS, NAME) \
-    STORAGECLASS mutex_t NAME = gl_lock_initializer;
-# define gl_lock_initializer \
-    DEFAULTMUTEX
-# define glthread_lock_init(LOCK) \
-    (thread_in_use () ? mutex_init (LOCK, USYNC_THREAD, NULL) : 0)
-# define glthread_lock_lock(LOCK) \
-    (thread_in_use () ? mutex_lock (LOCK) : 0)
-# define glthread_lock_unlock(LOCK) \
-    (thread_in_use () ? mutex_unlock (LOCK) : 0)
-# define glthread_lock_destroy(LOCK) \
-    (thread_in_use () ? mutex_destroy (LOCK) : 0)
-
-/* ------------------------- gl_rwlock_t datatype ------------------------- */
-
-typedef rwlock_t gl_rwlock_t;
-# define gl_rwlock_define(STORAGECLASS, NAME) \
-    STORAGECLASS rwlock_t NAME;
-# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
-    STORAGECLASS rwlock_t NAME = gl_rwlock_initializer;
-# define gl_rwlock_initializer \
-    DEFAULTRWLOCK
-# define glthread_rwlock_init(LOCK) \
-    (thread_in_use () ? rwlock_init (LOCK, USYNC_THREAD, NULL) : 0)
-# define glthread_rwlock_rdlock(LOCK) \
-    (thread_in_use () ? rw_rdlock (LOCK) : 0)
-# define glthread_rwlock_wrlock(LOCK) \
-    (thread_in_use () ? rw_wrlock (LOCK) : 0)
-# define glthread_rwlock_unlock(LOCK) \
-    (thread_in_use () ? rw_unlock (LOCK) : 0)
-# define glthread_rwlock_destroy(LOCK) \
-    (thread_in_use () ? rwlock_destroy (LOCK) : 0)
-
-/* --------------------- gl_recursive_lock_t datatype --------------------- */
-
-/* Old Solaris threads did not have recursive locks.
-   We have to implement them ourselves.  */
-
-typedef struct
-        {
-          mutex_t mutex;
-          thread_t owner;
-          unsigned long depth;
-        }
-        gl_recursive_lock_t;
-# define gl_recursive_lock_define(STORAGECLASS, NAME) \
-    STORAGECLASS gl_recursive_lock_t NAME;
-# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
-    STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
-# define gl_recursive_lock_initializer \
-    { DEFAULTMUTEX, (thread_t) 0, 0 }
-# define glthread_recursive_lock_init(LOCK) \
-    (thread_in_use () ? glthread_recursive_lock_init_multithreaded (LOCK) : 0)
-# define glthread_recursive_lock_lock(LOCK) \
-    (thread_in_use () ? glthread_recursive_lock_lock_multithreaded (LOCK) : 0)
-# define glthread_recursive_lock_unlock(LOCK) \
-    (thread_in_use () ? glthread_recursive_lock_unlock_multithreaded (LOCK) : 0)
-# define glthread_recursive_lock_destroy(LOCK) \
-    (thread_in_use () ? glthread_recursive_lock_destroy_multithreaded (LOCK) : 0)
-extern int glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock);
-extern int glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock);
-extern int glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock);
-extern int glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock);
-
-/* -------------------------- gl_once_t datatype -------------------------- */
-
-typedef struct
-        {
-          volatile int inited;
-          mutex_t mutex;
-        }
-        gl_once_t;
-# define gl_once_define(STORAGECLASS, NAME) \
-    STORAGECLASS gl_once_t NAME = { 0, DEFAULTMUTEX };
-# define glthread_once(ONCE_CONTROL, INITFUNCTION) \
-    (thread_in_use ()                                                          \
-     ? glthread_once_multithreaded (ONCE_CONTROL, INITFUNCTION)                \
-     : (glthread_once_singlethreaded (ONCE_CONTROL) ? (INITFUNCTION (), 0) : 0))
-extern int glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void));
-extern int glthread_once_singlethreaded (gl_once_t *once_control);
-
-# ifdef __cplusplus
-}
-# endif
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
@@ -807,7 +677,7 @@ typedef glwthread_once_t gl_once_t;
 
 /* ========================================================================= */
 
-#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WINDOWS_THREADS)
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS)
 
 /* Provide dummy implementation if threads are not supported.  */
 
diff --git a/lib/glthread/thread.c b/lib/glthread/thread.c
index 9da054242b..776bfb6bf4 100644
--- a/lib/glthread/thread.c
+++ b/lib/glthread/thread.c
@@ -15,8 +15,7 @@
    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
 
 /* Written by Bruno Haible <bruno@clisp.org>, 2005.
-   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
-   gthr-win32.h.  */
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-win32.h.  */
 
 #include <config.h>
 
diff --git a/lib/glthread/thread.h b/lib/glthread/thread.h
index bf4e74a5b3..eed2eb6e9c 100644
--- a/lib/glthread/thread.h
+++ b/lib/glthread/thread.h
@@ -15,8 +15,7 @@
    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
 
 /* Written by Bruno Haible <bruno@clisp.org>, 2005.
-   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
-   gthr-win32.h.  */
+   Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-win32.h.  */
 
 /* This file contains primitives for creating and controlling threads.
 
@@ -75,7 +74,7 @@
 #include <stdlib.h>
 
 #if !defined c11_threads_in_use
-# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK || USE_SOLARIS_THREADS_WEAK)
+# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK)
 #  include <threads.h>
 #  pragma weak thrd_exit
 #  define c11_threads_in_use() (thrd_exit != NULL)
@@ -277,60 +276,6 @@ typedef pth_t gl_thread_t;
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* Use the old Solaris threads library.  */
-
-# include <thread.h>
-# include <synch.h>
-
-# ifdef __cplusplus
-extern "C" {
-# endif
-
-# if USE_SOLARIS_THREADS_WEAK
-
-/* Use weak references to the old Solaris threads library.  */
-
-#  pragma weak thr_create
-#  pragma weak thr_join
-#  pragma weak thr_self
-#  pragma weak thr_exit
-
-#  pragma weak thr_suspend
-#  define thread_in_use() (thr_suspend != NULL || c11_threads_in_use ())
-
-# else
-
-#  define thread_in_use() 1
-
-# endif
-
-/* -------------------------- gl_thread_t datatype -------------------------- */
-
-typedef thread_t gl_thread_t;
-# define glthread_create(THREADP, FUNC, ARG) \
-    (thread_in_use () ? thr_create (NULL, 0, FUNC, ARG, 0, THREADP) : 0)
-# define glthread_sigmask(HOW, SET, OSET) \
-    (thread_in_use () ? sigprocmask (HOW, SET, OSET) : 0)
-# define glthread_join(THREAD, RETVALP) \
-    (thread_in_use () ? thr_join (THREAD, NULL, RETVALP) : 0)
-# define gl_thread_self() \
-    (thread_in_use () ? (void *) thr_self () : NULL)
-# define gl_thread_self_pointer() \
-    gl_thread_self ()
-# define gl_thread_exit(RETVAL) \
-    (thread_in_use () ? thr_exit (RETVAL) : 0)
-# define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
-
-# ifdef __cplusplus
-}
-# endif
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
@@ -367,7 +312,7 @@ typedef glwthread_thread_t gl_thread_t;
 
 /* ========================================================================= */
 
-#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WINDOWS_THREADS)
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS)
 
 /* Provide dummy implementation if threads are not supported.  */
 
diff --git a/lib/glthread/tls.c b/lib/glthread/tls.c
index 7a3e109d4f..cc6d4e1b4a 100644
--- a/lib/glthread/tls.c
+++ b/lib/glthread/tls.c
@@ -34,26 +34,6 @@
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* Use the old Solaris threads library.  */
-
-/* ------------------------- gl_tls_key_t datatype ------------------------- */
-
-void *
-glthread_tls_get_multithreaded (thread_key_t key)
-{
-  void *value;
-
-  if (thr_getspecific (key, &value) != 0)
-    abort ();
-  return value;
-}
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 #endif
diff --git a/lib/glthread/tls.h b/lib/glthread/tls.h
index 6c67de8911..a86dcd46ec 100644
--- a/lib/glthread/tls.h
+++ b/lib/glthread/tls.h
@@ -47,7 +47,7 @@
 #include <stdlib.h>
 
 #if !defined c11_threads_in_use
-# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK || USE_SOLARIS_THREADS_WEAK)
+# if HAVE_THREADS_H && (USE_POSIX_THREADS_WEAK || USE_PTH_THREADS_WEAK)
 #  include <threads.h>
 #  pragma weak thrd_exit
 #  define c11_threads_in_use() (thrd_exit != NULL)
@@ -179,58 +179,6 @@ typedef union
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* Use the old Solaris threads library.  */
-
-# include <thread.h>
-
-# if USE_SOLARIS_THREADS_WEAK
-
-/* Use weak references to the old Solaris threads library.  */
-
-#  pragma weak thr_keycreate
-#  pragma weak thr_getspecific
-#  pragma weak thr_setspecific
-
-#  pragma weak thr_suspend
-#  define thread_in_use() (thr_suspend != NULL || c11_threads_in_use ())
-
-# else
-
-#  define thread_in_use() 1
-
-# endif
-
-/* ------------------------- gl_tls_key_t datatype ------------------------- */
-
-typedef union
-        {
-          void *singlethread_value;
-          thread_key_t key;
-        }
-        gl_tls_key_t;
-# define glthread_tls_key_init(KEY, DESTRUCTOR) \
-    (thread_in_use ()                          \
-     ? thr_keycreate (&(KEY)->key, DESTRUCTOR) \
-     : ((KEY)->singlethread_value = NULL, 0))
-# define gl_tls_get(NAME) \
-    (thread_in_use ()                \
-     ? glthread_tls_get_multithreaded ((NAME).key) \
-     : (NAME).singlethread_value)
-extern void *glthread_tls_get_multithreaded (thread_key_t key);
-# define glthread_tls_set(KEY, POINTER) \
-    (thread_in_use ()                              \
-     ? thr_setspecific ((KEY)->key, (POINTER))     \
-     : ((KEY)->singlethread_value = (POINTER), 0))
-# define glthread_tls_key_destroy(KEY) \
-    /* Unsupported.  */ \
-    0
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
@@ -254,7 +202,7 @@ typedef glwthread_tls_key_t gl_tls_key_t;
 
 /* ========================================================================= */
 
-#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WINDOWS_THREADS)
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS)
 
 /* Provide dummy implementation if threads are not supported.  */
 
diff --git a/lib/glthread/yield.h b/lib/glthread/yield.h
index e139b986c4..3a2877b1a5 100644
--- a/lib/glthread/yield.h
+++ b/lib/glthread/yield.h
@@ -67,27 +67,6 @@ extern "C" {
 
 /* ========================================================================= */
 
-#if USE_SOLARIS_THREADS
-
-/* Use the old Solaris threads library.  */
-
-# include <thread.h>
-
-# ifdef __cplusplus
-extern "C" {
-# endif
-
-# define gl_thread_yield() \
-    thr_yield ()
-
-# ifdef __cplusplus
-}
-# endif
-
-#endif
-
-/* ========================================================================= */
-
 #if USE_WINDOWS_THREADS
 
 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
@@ -108,7 +87,7 @@ extern "C" {
 
 /* ========================================================================= */
 
-#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WINDOWS_THREADS)
+#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS)
 
 /* Provide dummy implementation if threads are not supported.  */
 
diff --git a/lib/regex_internal.h b/lib/regex_internal.h
index 5462419b78..16e18ca5b1 100644
--- a/lib/regex_internal.h
+++ b/lib/regex_internal.h
@@ -53,8 +53,6 @@
 #  define lock_define(name) pthread_mutex_t name;
 # elif USE_PTH_THREADS
 #  define lock_define(name) pth_mutex_t name;
-# elif USE_SOLARIS_THREADS
-#  define lock_define(name) mutex_t name;
 # elif USE_WINDOWS_THREADS
 #  define lock_define(name) gl_lock_t name;
 # else
diff --git a/m4/threadlib.m4 b/m4/threadlib.m4
index ca7bc47509..74b95b65e1 100644
--- a/m4/threadlib.m4
+++ b/m4/threadlib.m4
@@ -1,4 +1,4 @@
-# threadlib.m4 serial 18
+# threadlib.m4 serial 19
 dnl Copyright (C) 2005-2019 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -16,8 +16,8 @@ dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the
 dnl default is 'no', otherwise it is system dependent. In both cases, the user
 dnl can change the choice through the options --enable-threads=choice or
 dnl --disable-threads.
-dnl Defines at most one of the macros USE_POSIX_THREADS, USE_SOLARIS_THREADS,
-dnl USE_PTH_THREADS, USE_WINDOWS_THREADS
+dnl Defines at most one of the macros USE_POSIX_THREADS, USE_PTH_THREADS,
+dnl USE_WINDOWS_THREADS.
 dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
 dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
 dnl libtool).
@@ -52,7 +52,7 @@ AC_DEFUN([gl_THREADLIB_EARLY_BODY],
     [m4_divert_text([DEFAULTS], [gl_use_threads_default=])])
   m4_divert_text([DEFAULTS], [gl_use_winpthreads_default=])
   AC_ARG_ENABLE([threads],
-AC_HELP_STRING([--enable-threads={posix|solaris|pth|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
+AC_HELP_STRING([--enable-threads={posix|pth|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
 AC_HELP_STRING([--disable-threads], [build without multithread safety])]),
     [gl_use_threads=$enableval],
     [if test -n "$gl_use_threads_default"; then
@@ -250,37 +250,6 @@ int main ()
         fi
       fi
     fi
-    if test -z "$gl_have_pthread"; then
-      if test "$gl_use_threads" = yes || test "$gl_use_threads" = solaris; then
-        gl_have_solaristhread=
-        gl_save_LIBS="$LIBS"
-        LIBS="$LIBS -lthread"
-        AC_LINK_IFELSE(
-          [AC_LANG_PROGRAM(
-             [[
-#include <thread.h>
-#include <synch.h>
-             ]],
-             [[thr_self();]])],
-          [gl_have_solaristhread=yes])
-        LIBS="$gl_save_LIBS"
-        if test -n "$gl_have_solaristhread"; then
-          gl_threads_api=solaris
-          LIBTHREAD=-lthread
-          LTLIBTHREAD=-lthread
-          LIBMULTITHREAD="$LIBTHREAD"
-          LTLIBMULTITHREAD="$LTLIBTHREAD"
-          AC_DEFINE([USE_SOLARIS_THREADS], [1],
-            [Define if the old Solaris multithreading library can be used.])
-          if case "$gl_cv_have_weak" in *yes) true;; *) false;; esac; then
-            AC_DEFINE([USE_SOLARIS_THREADS_WEAK], [1],
-              [Define if references to the old Solaris multithreading library should be made weak.])
-            LIBTHREAD=
-            LTLIBTHREAD=
-          fi
-        fi
-      fi
-    fi
     if test "$gl_use_threads" = pth; then
       gl_save_CPPFLAGS="$CPPFLAGS"
       AC_LIB_LINKFLAGS([pth])
@@ -394,7 +363,6 @@ dnl
 dnl Mac OS X 10.[123]  posix      -lpthread       Y      OK
 dnl
 dnl Solaris 7,8,9      posix      -lpthread       Y      Sol 7,8: 0.0; Sol 9: OK
-dnl                    solaris    -lthread        Y      Sol 7,8: 0.0; Sol 9: OK
 dnl
 dnl HP-UX 11           posix      -lpthread       N (cc) OK
 dnl                                               Y (gcc)
diff --git a/tests/test-cond.c b/tests/test-cond.c
index 1de6783184..d8f76c66b3 100644
--- a/tests/test-cond.c
+++ b/tests/test-cond.c
@@ -16,7 +16,7 @@
 
 #include <config.h>
 
-#if USE_POSIX_THREADS || USE_SOLARIS_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
+#if USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
 
 /* Which tests to perform.
    Uncomment some of these, to verify that all tests crash if no locking
diff --git a/tests/test-lock.c b/tests/test-lock.c
index ca7dd62fbb..e3b4ce9f7b 100644
--- a/tests/test-lock.c
+++ b/tests/test-lock.c
@@ -18,14 +18,11 @@
 
 #include <config.h>
 
-#if USE_POSIX_THREADS || USE_SOLARIS_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
+#if USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
 
 #if USE_POSIX_THREADS
 # define TEST_POSIX_THREADS 1
 #endif
-#if USE_SOLARIS_THREADS
-# define TEST_SOLARIS_THREADS 1
-#endif
 #if USE_PTH_THREADS
 # define TEST_PTH_THREADS 1
 #endif
@@ -90,7 +87,6 @@
 
 #if !ENABLE_LOCKING
 # undef USE_POSIX_THREADS
-# undef USE_SOLARIS_THREADS
 # undef USE_PTH_THREADS
 # undef USE_WINDOWS_THREADS
 #endif
@@ -100,9 +96,6 @@
 # if TEST_POSIX_THREADS
 #  define USE_POSIX_THREADS 1
 # endif
-# if TEST_SOLARIS_THREADS
-#  define USE_SOLARIS_THREADS 1
-# endif
 # if TEST_PTH_THREADS
 #  define USE_PTH_THREADS 1
 # endif
diff --git a/tests/test-thread_create.c b/tests/test-thread_create.c
index f45edff6a8..fbfc561716 100644
--- a/tests/test-thread_create.c
+++ b/tests/test-thread_create.c
@@ -67,7 +67,7 @@ main ()
     }
   else
     {
-#if USE_POSIX_THREADS || USE_SOLARIS_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
+#if USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
       fputs ("glthread_create failed\n", stderr);
       return 1;
 #else
diff --git a/tests/test-tls.c b/tests/test-tls.c
index 2ce9f0d4d9..302ca18b89 100644
--- a/tests/test-tls.c
+++ b/tests/test-tls.c
@@ -18,14 +18,11 @@
 
 #include <config.h>
 
-#if USE_POSIX_THREADS || USE_SOLARIS_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
+#if USE_POSIX_THREADS || USE_PTH_THREADS || USE_WINDOWS_THREADS
 
 #if USE_POSIX_THREADS
 # define TEST_POSIX_THREADS 1
 #endif
-#if USE_SOLARIS_THREADS
-# define TEST_SOLARIS_THREADS 1
-#endif
 #if USE_PTH_THREADS
 # define TEST_PTH_THREADS 1
 #endif