From: Guy Harris <guy@alum.mit.edu>
Date: Mon, 22 Jan 2018 01:59:07 +0000 (-0800)
Subject: Don't test for __attribute__ in the configure script.
X-Git-Tag: libpcap-1.9-bp~275
X-Git-Url: https://git.tcpdump.org/libpcap/commitdiff_plain/4e84397255c98aa19f83bb1359a33fab1d15397f

Don't test for __attribute__ in the configure script.

Instead, use compiler test macros for the one remaining case where we
tested for __attribute__ to check whether that *particular* attribute is
supported.
---

diff --git a/aclocal.m4 b/aclocal.m4
index 243203c4..3689f6c8 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1062,36 +1062,3 @@ AC_DEFUN(AC_LBL_LIBRARY_NET, [
     # DLPI needs putmsg under HPUX so test for -lstr while we're at it
     AC_SEARCH_LIBS(putmsg, str)
 ])
-
-dnl
-dnl Test for __attribute__
-dnl
-
-AC_DEFUN(AC_C___ATTRIBUTE__, [
-AC_MSG_CHECKING(for __attribute__)
-AC_CACHE_VAL(ac_cv___attribute__, [
-AC_COMPILE_IFELSE([
-  AC_LANG_SOURCE([[
-#include <stdlib.h>
-
-static void foo(void) __attribute__ ((noreturn));
-
-static void
-foo(void)
-{
-  exit(1);
-}
-
-int
-main(int argc, char **argv)
-{
-  foo();
-}
-  ]])],
-ac_cv___attribute__=yes,
-ac_cv___attribute__=no)])
-if test "$ac_cv___attribute__" = "yes"; then
-  AC_DEFINE(HAVE___ATTRIBUTE__, 1, [define if your compiler has __attribute__])
-fi
-AC_MSG_RESULT($ac_cv___attribute__)
-])
diff --git a/cmakeconfig.h.in b/cmakeconfig.h.in
index a406cd94..095bcf8e 100644
--- a/cmakeconfig.h.in
+++ b/cmakeconfig.h.in
@@ -244,9 +244,6 @@
 /* Define to 1 if you have the `PacketIsLoopbackAdapter' function. */
 #cmakedefine HAVE_PACKET_IS_LOOPBACK_ADAPTER 1
 
-/* define if your compiler has __attribute__ */
-#cmakedefine HAVE___ATTRIBUTE__ 1
-
 /* IPv6 */
 #cmakedefine INET6 1
 
diff --git a/config.h.in b/config.h.in
index 13d0bd7e..042fb756 100644
--- a/config.h.in
+++ b/config.h.in
@@ -244,9 +244,6 @@
 /* Define to 1 if you have the `vsnprintf' function. */
 #undef HAVE_VSNPRINTF
 
-/* define if your compiler has __attribute__ */
-#undef HAVE___ATTRIBUTE__
-
 /* IPv6 */
 #undef INET6
 
diff --git a/configure b/configure
index 7428e08b..c9bb8a83 100755
--- a/configure
+++ b/configure
@@ -4070,50 +4070,6 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __attribute__" >&5
-$as_echo_n "checking for __attribute__... " >&6; }
-if ${ac_cv___attribute__+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-
-#include <stdlib.h>
-
-static void foo(void) __attribute__ ((noreturn));
-
-static void
-foo(void)
-{
-  exit(1);
-}
-
-int
-main(int argc, char **argv)
-{
-  foo();
-}
-
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  ac_cv___attribute__=yes
-else
-  ac_cv___attribute__=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-
-if test "$ac_cv___attribute__" = "yes"; then
-
-$as_echo "#define HAVE___ATTRIBUTE__ 1" >>confdefs.h
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv___attribute__" >&5
-$as_echo "$ac_cv___attribute__" >&6; }
-
-
 #
 # Try to arrange for large file support.
 #
diff --git a/configure.ac b/configure.ac
index b008689f..5e46cf54 100644
--- a/configure.ac
+++ b/configure.ac
@@ -31,7 +31,6 @@ AC_PROG_CC_C99
 AC_LBL_C_INIT(V_CCOPT, V_INCLS)
 AC_LBL_SHLIBS_INIT
 AC_LBL_C_INLINE
-AC_C___ATTRIBUTE__
 
 #
 # Try to arrange for large file support.
diff --git a/extract.h b/extract.h
index 8a8b6024..aa3ff991 100644
--- a/extract.h
+++ b/extract.h
@@ -24,6 +24,7 @@
 #endif
 
 #include <pcap/pcap-inttypes.h>
+#include <pcap/compiler-tests.h>
 
 /*
  * Macros to extract possibly-unaligned big-endian integral values.
@@ -32,15 +33,16 @@
 /*
  * The processor doesn't natively handle unaligned loads.
  */
-#if defined(__GNUC__) && defined(HAVE___ATTRIBUTE__) && \
+#if PCAP_IS_AT_LEAST_GNUC_VERSION(2,0) && \
     (defined(__alpha) || defined(__alpha__) || \
      defined(__mips) || defined(__mips__))
-
 /*
- * This is a GCC-compatible compiler and we have __attribute__, which
- * we assume that mean we have __attribute__((packed)), and this is
- * MIPS or Alpha, which has instructions that can help when doing
- * unaligned loads.
+ * This is MIPS or Alpha, which don't natively handle unaligned loads,
+ * but which have instructions that can help when doing unaligned
+ * loads, and this is GCC 2.0 or later or a compiler that claims to
+ * be GCC 2.0 or later, which we assume that mean we have
+ * __attribute__((packed)), which we can use to convince the compiler
+ * to generate those instructions.
  *
  * Declare packed structures containing a uint16_t and a uint32_t,
  * cast the pointer to point to one of those, and fetch through it;