Only check for pcap_breakloop()'s "usability" if it might be present but

unusable; it'd only be unusable if we require that functions be declared
before they're used (i.e., if we check for that with -Wimplicit and if
we fail if the check produces a warning because we're using -Werror).
Always checking doesn't necessarily work if, for example, you're not
compiling with GCC, as -Werror and -Wimplicit might not be recognized by
other compilers.

svn path=/trunk/; revision=24287

diff --git a/acinclude.m4 b/acinclude.m4
index d711fe83618fb3fdd49faa8575c9461fd6ba9b7b..8277f2ff84f69b4e38535a1293abc076ae2778eb 100644 (file)
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -467,13 +467,20 @@ and did you also install that package?]]))
        fi
        AC_CHECK_FUNCS(pcap_open_dead pcap_freecode)
        #
-       # pcap_breakloop may be present in the library and not declared in the
-       # header file. We are therefore testing whether the function is present
-       # first and then if it is usable. It is usable if it compiles without
-       # an implicit warning. If it is not usable, we output a warning telling
-       # the user to update his pcap header.
+       # pcap_breakloop may be present in the library but not declared
+       # in the pcap.h header file.  If it's not declared in the header
+       # file, attempts to use it will get warnings, and, if we're
+       # building with warnings treated as errors, that warning will
+       # cause compilation to fail.
+       #
+       # We are therefore first testing whether the function is present
+       # and then, if we're compiling with warnings as errors, testing
+       # whether it is usable.  It is usable if it compiles without
+       # a -Wimplicit warning (the "compile with warnings as errors"
+       # option requires GCC). If it is not usable, we fail and tell
+       # the user that the pcap.h header needs to be updated.
        # 
-       # Ceteris paribus, it should only happen with Mac OS X 10.3[.x] which
+       # Ceteris paribus, this should only happen with Mac OS X 10.3[.x] which
        # can have an up-to-date pcap library without the corresponding pcap
        # header.
        #
@@ -482,25 +489,31 @@ and did you also install that package?]]))
        # e.g. hand made symbolic link from libpcap.so -> libpcap.so.0.8 but
        # having the pcap header version 0.7.
        #
-       AC_MSG_CHECKING([whether pcap_breakloop is present and usable])
+       AC_MSG_CHECKING([whether pcap_breakloop is present])
        ac_CFLAGS_saved="$CFLAGS"
        AC_WIRESHARK_PCAP_BREAKLOOP_TRY_LINK
        if test "x$ws_breakloop_compiled" = "xyes"; then
-         CFLAGS="$CFLAGS -Werror -Wimplicit"
-         AC_WIRESHARK_PCAP_BREAKLOOP_TRY_LINK
-         if test "x$ws_breakloop_compiled" = "xyes"; then
-           AC_MSG_RESULT(yes)
-           AC_DEFINE(HAVE_PCAP_BREAKLOOP, 1, [Define if pcap_breakloop is known])
-         else
-           AC_MSG_RESULT(broken)
-           AC_MSG_WARN([Your pcap library is more recent than your pcap header.])
-           AC_MSG_WARN([Wireshark won't be able to use functions not declared])
-           AC_MSG_WARN([in that header. You should install a newer version of])
-           AC_MSG_WARN([the header file.])
+         AC_MSG_RESULT(yes)
+         AC_DEFINE(HAVE_PCAP_BREAKLOOP, 1, [Define if pcap_breakloop is known])
+         if test "x$with_warnings_as_errors" = "xyes"; then
+           AC_MSG_CHECKING([whether pcap_breakloop is usable])
+           CFLAGS="$CFLAGS -Werror -Wimplicit"
+           AC_WIRESHARK_PCAP_BREAKLOOP_TRY_LINK
+           if test "x$ws_breakloop_compiled" = "xyes"; then
+             AC_MSG_RESULT(yes)
+           else
+             AC_MSG_RESULT(no)
+             AC_MSG_ERROR(
+[Your pcap library is more recent than your pcap header.
+As you are building with compiler warnings treated as errors, Wireshark
+won't be able to use functions not declared in that header.
+If you wish to build with compiler warnings treated as errors, You should
+install a newer version of the header file.])
+           fi
+           CFLAGS="$ac_CFLAGS_saved"
          fi
-         CFLAGS="$ac_CFLAGS_saved"
        else
-         AC_MSG_RESULT(function not present)
+         AC_MSG_RESULT(no)
        fi
 
        #