The option --disable-threads from the 'threadlib' module was only meant to
have an effect on the gnulib modules that use the Gnulib multithreading API
internally. But from the 'configure --help' output, David Edelsohn got the
impression that this option should apply also to the gnulib code that tests
HAVE_PTHREAD_API. Since the ability to build a library without dependency
on -lpthread can be seen as a useful feature, I'm implementing it here.
2023-11-17 Bruno Haible <br...@clisp.org>
mbrtowc, mbrtoc32, nl_langinfo, setlocale-null: Obey --disable-threads.
Reported by David Edelsohn <dje....@gmail.com> in
<https://gcc.gnu.org/pipermail/gcc-patches/2023-November/636830.html>,
<https://gcc.gnu.org/pipermail/gcc-patches/2023-November/636843.html>.
* m4/threadlib.m4 (gl_THREADLIB_BODY): If --disable-threads was
specified, define AVOID_ANY_THREADS to 1.
* lib/mbtowc-lock.c: Omit all code if --disable-threads was specified.
* lib/nl_langinfo-lock.c: Likewise.
* lib/setlocale-lock.c: Likewise.
* lib/mbtowc-lock.h: Omit locking code if --disable-threads was
specified.
* lib/nl_langinfo.c: Likewise.
* lib/setlocale_null.c: Likewise.
* lib/mbrtowc.c: Don't include any multithreading headers if
--disable-threads was specified.
* lib/mbrtoc32.c: Likewise.
diff --git a/lib/mbrtoc32.c b/lib/mbrtoc32.c
index 0933437a4b..755d092e05 100644
--- a/lib/mbrtoc32.c
+++ b/lib/mbrtoc32.c
@@ -41,7 +41,11 @@
branch below.
They are equivalent. */
-# if defined _WIN32 && !defined __CYGWIN__
+# if AVOID_ANY_THREADS
+
+/* The option '--disable-threads' explicitly requests no locking. */
+
+# elif defined _WIN32 && !defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN /* avoid including junk */
# include <windows.h>
diff --git a/lib/mbrtowc.c b/lib/mbrtowc.c
index c1a689a270..0a061906d7 100644
--- a/lib/mbrtowc.c
+++ b/lib/mbrtowc.c
@@ -28,7 +28,11 @@
# include <stdint.h>
# include <stdlib.h>
-# if defined _WIN32 && !defined __CYGWIN__
+# if AVOID_ANY_THREADS
+
+/* The option '--disable-threads' explicitly requests no locking. */
+
+# elif defined _WIN32 && !defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN /* avoid including junk */
# include <windows.h>
diff --git a/lib/mbtowc-lock.c b/lib/mbtowc-lock.c
index c4d0b088f6..9d16068263 100644
--- a/lib/mbtowc-lock.c
+++ b/lib/mbtowc-lock.c
@@ -18,9 +18,10 @@
#include <config.h>
+/* The option '--disable-threads' explicitly requests no locking. */
/* When it is known that the gl_get_mbtowc_lock function is defined
by a dependency library, it should not be defined here. */
-#if OMIT_MBTOWC_LOCK
+#if AVOID_ANY_THREADS || OMIT_MBTOWC_LOCK
/* This declaration is solely to ensure that after preprocessing
this file is never empty. */
diff --git a/lib/mbtowc-lock.h b/lib/mbtowc-lock.h
index beb37722f5..b0cc80c6a6 100644
--- a/lib/mbtowc-lock.h
+++ b/lib/mbtowc-lock.h
@@ -32,7 +32,7 @@ mbtowc_unlocked (wchar_t *pwc, const char *p, size_t m)
/* Prohibit renaming this symbol. */
#undef gl_get_mbtowc_lock
-#if GNULIB_MBRTOWC_SINGLE_THREAD
+#if AVOID_ANY_THREADS || GNULIB_MBRTOWC_SINGLE_THREAD
/* All uses of this function are in a single thread. No locking needed. */
diff --git a/lib/nl_langinfo-lock.c b/lib/nl_langinfo-lock.c
index fb12299959..f4cea0c290 100644
--- a/lib/nl_langinfo-lock.c
+++ b/lib/nl_langinfo-lock.c
@@ -18,9 +18,10 @@
#include <config.h>
+/* The option '--disable-threads' explicitly requests no locking. */
/* When it is known that the gl_get_nl_langinfo_lock function is defined
by a dependency library, it should not be defined here. */
-#if OMIT_NL_LANGINFO_LOCK
+#if AVOID_ANY_THREADS || OMIT_NL_LANGINFO_LOCK
/* This declaration is solely to ensure that after preprocessing
this file is never empty. */
diff --git a/lib/nl_langinfo.c b/lib/nl_langinfo.c
index f872c6d5e2..3be275510e 100644
--- a/lib/nl_langinfo.c
+++ b/lib/nl_langinfo.c
@@ -30,7 +30,12 @@
#endif
#if REPLACE_NL_LANGINFO && !NL_LANGINFO_MTSAFE
-# if defined _WIN32 && !defined __CYGWIN__
+
+# if AVOID_ANY_THREADS
+
+/* The option '--disable-threads' explicitly requests no locking. */
+
+# elif defined _WIN32 && !defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN /* avoid including junk */
# include <windows.h>
@@ -51,6 +56,7 @@
# include <threads.h>
# endif
+
#endif
/* nl_langinfo() must be multithread-safe. To achieve this without using
@@ -186,7 +192,12 @@ nl_langinfo_unlocked (nl_item item)
/* Prohibit renaming this symbol. */
# undef gl_get_nl_langinfo_lock
-# if defined _WIN32 && !defined __CYGWIN__
+# if AVOID_ANY_THREADS
+
+/* The option '--disable-threads' explicitly requests no locking. */
+# define nl_langinfo_with_lock nl_langinfo_unlocked
+
+# elif defined _WIN32 && !defined __CYGWIN__
extern __declspec(dllimport) CRITICAL_SECTION *gl_get_nl_langinfo_lock (void);
diff --git a/lib/setlocale-lock.c b/lib/setlocale-lock.c
index 593f63711b..090f824abe 100644
--- a/lib/setlocale-lock.c
+++ b/lib/setlocale-lock.c
@@ -18,9 +18,10 @@
#include <config.h>
+/* The option '--disable-threads' explicitly requests no locking. */
/* When it is known that the gl_get_setlocale_null_lock function is defined
by a dependency library, it should not be defined here. */
-#if OMIT_SETLOCALE_LOCK
+#if AVOID_ANY_THREADS || OMIT_SETLOCALE_LOCK
/* This declaration is solely to ensure that after preprocessing
this file is never empty. */
diff --git a/lib/setlocale_null.c b/lib/setlocale_null.c
index 89c8a06598..9d7cb785f7 100644
--- a/lib/setlocale_null.c
+++ b/lib/setlocale_null.c
@@ -30,7 +30,12 @@
#endif
#if !(SETLOCALE_NULL_ALL_MTSAFE && SETLOCALE_NULL_ONE_MTSAFE)
-# if defined _WIN32 && !defined __CYGWIN__
+
+# if AVOID_ANY_THREADS
+
+/* The option '--disable-threads' explicitly requests no locking. */
+
+# elif defined _WIN32 && !defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN /* avoid including junk */
# include <windows.h>
@@ -51,6 +56,7 @@
# include <threads.h>
# endif
+
#endif
/* Use the system's setlocale() function, not the gnulib override, here. */
@@ -181,7 +187,12 @@ setlocale_null_unlocked (int category, char *buf, size_t
bufsize)
/* Prohibit renaming this symbol. */
# undef gl_get_setlocale_null_lock
-# if defined _WIN32 && !defined __CYGWIN__
+# if AVOID_ANY_THREADS
+
+/* The option '--disable-threads' explicitly requests no locking. */
+# define setlocale_null_with_lock setlocale_null_unlocked
+
+# elif defined _WIN32 && !defined __CYGWIN__
extern __declspec(dllimport) CRITICAL_SECTION *gl_get_setlocale_null_lock
(void);
diff --git a/m4/threadlib.m4 b/m4/threadlib.m4
index 855e563d88..b35ad53fd8 100644
--- a/m4/threadlib.m4
+++ b/m4/threadlib.m4
@@ -1,4 +1,4 @@
-# threadlib.m4 serial 40
+# threadlib.m4 serial 41
dnl Copyright (C) 2005-2023 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -584,6 +584,10 @@ AC_DEFUN([gl_THREADLIB_BODY]
;;
esac
fi
+ else
+ dnl "$gl_use_threads" is "no".
+ AC_DEFINE([AVOID_ANY_THREADS], [1],
+ [Define if no multithread safety and no multithreading is desired.])
fi
AC_MSG_CHECKING([for multithread API to use])
AC_MSG_RESULT([$gl_threads_api])
