From b0afb8fe0ff1d87165af9df61501197a06240dda Mon Sep 17 00:00:00 2001
From: Lorenz Kästle <12514511+RincewindsHat@users.noreply.github.com>
Date: Sun, 28 Dec 2025 12:13:40 +0100
Subject: Sync with Gnulib stable-202507 code (a8ac9f9ce5)

---
 gl/m4/pthread-spin.m4 | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 gl/m4/pthread-spin.m4

(limited to 'gl/m4/pthread-spin.m4')

diff --git a/gl/m4/pthread-spin.m4 b/gl/m4/pthread-spin.m4
new file mode 100644
index 00000000..aae2fb3b
--- /dev/null
+++ b/gl/m4/pthread-spin.m4
@@ -0,0 +1,72 @@
+# pthread-spin.m4
+# serial 8
+dnl Copyright (C) 2019-2025 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.
+dnl This file is offered as-is, without any warranty.
+
+AC_DEFUN_ONCE([gl_PTHREAD_SPIN],
+[
+  AC_REQUIRE([gl_PTHREAD_H_PART1])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  if { case "$host_os" in mingw* | windows*) true;; *) false;; esac; } \
+     && test $gl_threads_api = windows; then
+    dnl Choose function names that don't conflict with the mingw-w64 winpthreads
+    dnl library.
+    REPLACE_PTHREAD_SPIN_INIT=1
+    REPLACE_PTHREAD_SPIN_LOCK=1
+    REPLACE_PTHREAD_SPIN_TRYLOCK=1
+    REPLACE_PTHREAD_SPIN_UNLOCK=1
+    REPLACE_PTHREAD_SPIN_DESTROY=1
+  else
+    if test $HAVE_PTHREAD_H = 0 || test $HAVE_PTHREAD_SPINLOCK_T = 0; then
+      HAVE_PTHREAD_SPIN_INIT=0
+      HAVE_PTHREAD_SPIN_LOCK=0
+      HAVE_PTHREAD_SPIN_TRYLOCK=0
+      HAVE_PTHREAD_SPIN_UNLOCK=0
+      HAVE_PTHREAD_SPIN_DESTROY=0
+    else
+      dnl Test whether the gnulib module 'threadlib' is in use.
+      dnl Some packages like Emacs use --avoid=threadlib.
+      dnl Write the symbol in such a way that it does not cause 'aclocal' to pick
+      dnl the threadlib.m4 file that is installed in $PREFIX/share/aclocal/.
+      m4_ifdef([gl_][THREADLIB], [
+        AC_REQUIRE([gl_][THREADLIB])
+        dnl Test whether the functions actually exist.
+        dnl FreeBSD 5.2.1 declares them but does not define them.
+        AC_CACHE_CHECK([for pthread_spin_init],
+          [gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD],
+          [gl_saved_LIBS="$LIBS"
+           LIBS="$LIBS $LIBMULTITHREAD"
+           AC_LINK_IFELSE(
+             [AC_LANG_PROGRAM(
+                [[#include <pthread.h>
+                ]],
+                [[pthread_spinlock_t lock;
+                  return pthread_spin_init (&lock, 0);
+                ]])
+             ],
+             [gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD=yes],
+             [gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD=no])
+           LIBS="$gl_saved_LIBS"
+          ])
+        if test $gl_cv_func_pthread_spin_init_in_LIBMULTITHREAD != yes; then
+          HAVE_PTHREAD_SPIN_INIT=0
+          REPLACE_PTHREAD_SPIN_INIT=1
+          HAVE_PTHREAD_SPIN_LOCK=0
+          REPLACE_PTHREAD_SPIN_LOCK=1
+          HAVE_PTHREAD_SPIN_TRYLOCK=0
+          REPLACE_PTHREAD_SPIN_TRYLOCK=1
+          HAVE_PTHREAD_SPIN_UNLOCK=0
+          REPLACE_PTHREAD_SPIN_UNLOCK=1
+          HAVE_PTHREAD_SPIN_DESTROY=0
+          REPLACE_PTHREAD_SPIN_DESTROY=1
+        fi
+      ], [
+        :
+      ])
+    fi
+  fi
+])
-- 
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