Use compiler tests to determine how to define _U_.

One less thing that has to be done in autotools and CMake.

15 files changed, 78 insertions, 96 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5b307403..4d57446c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -247,11 +247,6 @@ add_definitions(-DBUILDING_PCAP)
 if(MSVC)
     add_definitions(-D__STDC__)
     add_definitions(-D_CRT_SECURE_NO_WARNINGS)
-    add_definitions("-D_U_=")
-elseif(CMAKE_COMPILER_IS_GNUCXX)
-    add_definitions("-D_U_=__attribute__((unused))")
-else(MSVC)
-    add_definitions("-D_U_=")
 endif(MSVC)
 
 if(USE_STATIC_RT)
diff --git a/Makefile.in b/Makefile.in
index 136e84e0..4a803467 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -155,7 +155,8 @@ HDR = $(PUBHDR) \
 	rpcapd/win32-svc.h \
 	sf-pcap.h \
 	sf-pcap-ng.h \
-	sunatmpos.h
+	sunatmpos.h \
+	varattrs.h
 
 TESTS = \
 	@VALGRINDTEST@ \
diff --git a/aclocal.m4 b/aclocal.m4
index f922759f..4362d4ff 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1101,49 +1101,11 @@ ac_cv___attribute__=yes,
 ac_cv___attribute__=no)])
 if test "$ac_cv___attribute__" = "yes"; then
   AC_DEFINE(HAVE___ATTRIBUTE__, 1, [define if your compiler has __attribute__])
-else
-  #
-  # We can't use __attribute__, so we can't use __attribute__((unused)),
-  # so we define _U_ to an empty string.
-  #
-  V_DEFS="$V_DEFS -D_U_=\"\""
 fi
 AC_MSG_RESULT($ac_cv___attribute__)
 ])
 
 dnl
-dnl Test whether __attribute__((unused)) can be used without warnings
-dnl
-
-AC_DEFUN(AC_C___ATTRIBUTE___UNUSED, [
-AC_MSG_CHECKING([whether __attribute__((unused)) can be used without warnings])
-AC_CACHE_VAL(ac_cv___attribute___unused, [
-save_CFLAGS="$CFLAGS"
-CFLAGS="$CFLAGS $ac_lbl_cc_force_warning_errors"
-AC_COMPILE_IFELSE([
-  AC_LANG_SOURCE([[
-#include <stdlib.h>
-#include <stdio.h>
-
-int
-main(int argc  __attribute((unused)), char **argv __attribute((unused)))
-{
-  printf("Hello, world!\n");
-  return 0;
-}
-  ]])],
-ac_cv___attribute___unused=yes,
-ac_cv___attribute___unused=no)])
-CFLAGS="$save_CFLAGS"
-if test "$ac_cv___attribute___unused" = "yes"; then
-  V_DEFS="$V_DEFS -D_U_=\"__attribute__((unused))\""
-else
-  V_DEFS="$V_DEFS -D_U_=\"\""
-fi
-AC_MSG_RESULT($ac_cv___attribute___unused)
-])
-
-dnl
 dnl Checks to see if tpacket_stats is defined in linux/if_packet.h
 dnl If so then pcap-linux.c can use this to report proper statistics.
 dnl
diff --git a/configure b/configure
index 30c6bdc1..8b9a8ea6 100755
--- a/configure
+++ b/configure
@@ -3870,59 +3870,10 @@ if test "$ac_cv___attribute__" = "yes"; then
 
 $as_echo "#define HAVE___ATTRIBUTE__ 1" >>confdefs.h
 
-else
-  #
-  # We can't use __attribute__, so we can't use __attribute__((unused)),
-  # so we define _U_ to an empty string.
-  #
-  V_DEFS="$V_DEFS -D_U_=\"\""
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv___attribute__" >&5
 $as_echo "$ac_cv___attribute__" >&6; }
 
-if test "$ac_cv___attribute__" = "yes"; then
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether __attribute__((unused)) can be used without warnings" >&5
-$as_echo_n "checking whether __attribute__((unused)) can be used without warnings... " >&6; }
-if ${ac_cv___attribute___unused+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-
-save_CFLAGS="$CFLAGS"
-CFLAGS="$CFLAGS $ac_lbl_cc_force_warning_errors"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-
-#include <stdlib.h>
-#include <stdio.h>
-
-int
-main(int argc  __attribute((unused)), char **argv __attribute((unused)))
-{
-  printf("Hello, world!\n");
-  return 0;
-}
-
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  ac_cv___attribute___unused=yes
-else
-  ac_cv___attribute___unused=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-
-CFLAGS="$save_CFLAGS"
-if test "$ac_cv___attribute___unused" = "yes"; then
-  V_DEFS="$V_DEFS -D_U_=\"__attribute__((unused))\""
-else
-  V_DEFS="$V_DEFS -D_U_=\"\""
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv___attribute___unused" >&5
-$as_echo "$ac_cv___attribute___unused" >&6; }
-
-fi
 
 #
 # Try to arrange for large file support.
diff --git a/configure.ac b/configure.ac
index a20f376a..7f16399c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -28,9 +28,6 @@ AC_LBL_C_INIT(V_CCOPT, V_INCLS)
 AC_LBL_SHLIBS_INIT
 AC_LBL_C_INLINE
 AC_C___ATTRIBUTE__
-if test "$ac_cv___attribute__" = "yes"; then
-	AC_C___ATTRIBUTE___UNUSED
-fi
 
 #
 # Try to arrange for large file support.
diff --git a/pcap-int.h b/pcap-int.h
index d1ea4a15..516b49c3 100644
--- a/pcap-int.h
+++ b/pcap-int.h
@@ -38,6 +38,7 @@
 
 #include <pcap/pcap.h>
 
+#include "varattrs.h"
 #include "fmtutils.h"
 
 /*
diff --git a/tests/can_set_rfmon_test.c b/tests/can_set_rfmon_test.c
index 88661d63..ea4f0c40 100644
--- a/tests/can_set_rfmon_test.c
+++ b/tests/can_set_rfmon_test.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
diff --git a/tests/capturetest.c b/tests/capturetest.c
index 1cebae01..573239f2 100644
--- a/tests/capturetest.c
+++ b/tests/capturetest.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
diff --git a/tests/filtertest.c b/tests/filtertest.c
index 9d597396..380cb73e 100644
--- a/tests/filtertest.c
+++ b/tests/filtertest.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
diff --git a/tests/opentest.c b/tests/opentest.c
index 79c9c941..bad38eb0 100644
--- a/tests/opentest.c
+++ b/tests/opentest.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
diff --git a/tests/reactivatetest.c b/tests/reactivatetest.c
index f3485cbd..42b2c3b8 100644
--- a/tests/reactivatetest.c
+++ b/tests/reactivatetest.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
diff --git a/tests/selpolltest.c b/tests/selpolltest.c
index f8005d6e..dbd1c424 100644
--- a/tests/selpolltest.c
+++ b/tests/selpolltest.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
diff --git a/tests/threadsignaltest.c b/tests/threadsignaltest.c
index 2a493223..bd46f936 100644
--- a/tests/threadsignaltest.c
+++ b/tests/threadsignaltest.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
diff --git a/tests/valgrindtest.c b/tests/valgrindtest.c
index 6bb6d4f6..ef387c97 100644
--- a/tests/valgrindtest.c
+++ b/tests/valgrindtest.c
@@ -19,6 +19,8 @@
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include "varattrs.h"
+
 /*
  * This doesn't actually test libpcap itself; it tests whether
  * valgrind properly handles the APIs libpcap uses.  If it doesn't,
diff --git a/varattrs.h b/varattrs.h
new file mode 100644
index 00000000..05bfe8cd
--- /dev/null
+++ b/varattrs.h
@@ -0,0 +1,59 @@
+/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
+/*
+ * Copyright (c) 1993, 1994, 1995, 1996, 1997
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the Computer Systems
+ *	Engineering Group at Lawrence Berkeley Laboratory.
+ * 4. Neither the name of the University nor of the Laboratory may be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef varattrs_h
+#define varattrs_h
+
+#include <pcap/compiler-tests.h>
+
+/*
+ * Attributes to apply to variables, using various compiler-specific
+ * extensions.
+ */
+
+#if __has_attribute(unused) \
+    || PCAP_IS_AT_LEAST_GNUC_VERSION(2,0)
+  /*
+   * Compiler with support for __attribute__((unused)), or GCC 2.0 and
+   * later, so it supports __attribute__((unused)).
+   */
+  #define _U_ __attribute__((unused))
+#else
+  /*
+   * We don't know of any way to mark a variable as unused.
+   */
+  #define _U_
+#endif
+
+#endif