Re: [PATCH] Do not decorate symbols as dllexport on Cygwin

[Bruno Haible]

Corinna Vinschen wrote:
> This patch will be in the next Cygwin release 3.4.6.

Thanks!

> I'm just a bit fuzzy what patches will be required for gnulib now...

With this patch, the setlocale_null lock should be gone in Cygwin >= 3.4.6.
I can't really test it, but I hope the patch is correct.


2023-02-06  Bruno Haible  <bruno@clisp.org>

        setlocale-null: Don't use a lock in Cygwin >= 3.4.6.
        Road paved by Corinna Vinschen <vinschen@redhat.com>.
        * m4/setlocale_null.m4 (gl_FUNC_SETLOCALE_NULL): Assume that
        setlocale (LC_ALL, NULL) is multithread-safe in Cygwin >= 3.4.6.
        * lib/setlocale_null.c: Update comments.
        * tests/test-setlocale_null-mt-all.c: Likewise.

diff --git a/lib/setlocale_null.c b/lib/setlocale_null.c
index 6ac563db14..89c8a06598 100644
--- a/lib/setlocale_null.c
+++ b/lib/setlocale_null.c
@@ -173,7 +173,7 @@ setlocale_null_unlocked (int category, char *buf, size_t 
bufsize)
 #endif
 }
 
-#if !(SETLOCALE_NULL_ALL_MTSAFE && SETLOCALE_NULL_ONE_MTSAFE) /* musl libc, 
macOS, FreeBSD, NetBSD, OpenBSD, AIX, Haiku, Cygwin */
+#if !(SETLOCALE_NULL_ALL_MTSAFE && SETLOCALE_NULL_ONE_MTSAFE) /* musl libc, 
macOS, FreeBSD, NetBSD, OpenBSD, AIX, Haiku, Cygwin < 3.4.6 */
 
 /* Use a lock, so that no two threads can invoke setlocale_null_unlocked
    at the same time.  */
@@ -198,7 +198,7 @@ setlocale_null_with_lock (int category, char *buf, size_t 
bufsize)
   return ret;
 }
 
-# elif HAVE_PTHREAD_API /* musl libc, macOS, FreeBSD, NetBSD, OpenBSD, AIX, 
Haiku, Cygwin */
+# elif HAVE_PTHREAD_API /* musl libc, macOS, FreeBSD, NetBSD, OpenBSD, AIX, 
Haiku, Cygwin < 3.4.6 */
 
 extern
 #  if defined _WIN32 || defined __CYGWIN__
diff --git a/m4/setlocale_null.m4 b/m4/setlocale_null.m4
index dd6a5ef538..b41df499a8 100644
--- a/m4/setlocale_null.m4
+++ b/m4/setlocale_null.m4
@@ -1,4 +1,4 @@
-# setlocale_null.m4 serial 6
+# setlocale_null.m4 serial 7
 dnl Copyright (C) 2019-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -13,9 +13,23 @@ AC_DEFUN([gl_FUNC_SETLOCALE_NULL],
   AC_CACHE_CHECK([whether setlocale (LC_ALL, NULL) is multithread-safe],
     [gl_cv_func_setlocale_null_all_mtsafe],
     [case "$host_os" in
-       # Guess no on musl libc, macOS, FreeBSD, NetBSD, OpenBSD, AIX, Haiku, 
Cygwin.
-       *-musl* | darwin* | freebsd* | midnightbsd* | netbsd* | openbsd* | aix* 
| haiku* | cygwin*)
+       # Guess no on musl libc, macOS, FreeBSD, NetBSD, OpenBSD, AIX, Haiku.
+       *-musl* | darwin* | freebsd* | midnightbsd* | netbsd* | openbsd* | aix* 
| haiku*)
          gl_cv_func_setlocale_null_all_mtsafe=no ;;
+       # Guess no on Cygwin < 3.4.6.
+       cygwin*)
+         AC_EGREP_CPP([Lucky user],
+           [
+#if defined __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED >= CYGWIN_VERSION_DLL_MAKE_COMBINED (3004, 6)
+  Lucky user
+ #endif
+#endif
+          ],
+          [gl_cv_func_setlocale_null_all_mtsafe=yes],
+          [gl_cv_func_setlocale_null_all_mtsafe=no])
+        ;;
        # Guess yes on glibc, HP-UX, IRIX, Solaris, native Windows.
        *-gnu* | gnu* | hpux* | irix* | solaris* | mingw*)
          gl_cv_func_setlocale_null_all_mtsafe=yes ;;
diff --git a/tests/test-setlocale_null-mt-all.c 
b/tests/test-setlocale_null-mt-all.c
index 6036c260cd..7480406639 100644
--- a/tests/test-setlocale_null-mt-all.c
+++ b/tests/test-setlocale_null-mt-all.c
@@ -166,7 +166,7 @@ Solaris 11.0         OK
 Solaris 11.4         OK
 Solaris OpenIndiana  OK
 Haiku                crash < 1 sec
-Cygwin               crash < 1 sec
+Cygwin < 3.4.6       crash < 1 sec
 mingw                OK
 MSVC                 OK (assuming compiler option /MD !)
 */