Compile with -Wcast-qual.

That let me find what might have been the bulk of the 579(!) instances
of "Deconst" reported in

    http://www.cl.cam.ac.uk/~dc552/papers/asplos15-memory-safe-c.pdf

and, hopefully, will prevent more from creeping in.

There are some remaining ones - and they represent attempts to overwrite
the packet bytes handed to tcpdump by libpcap, which could well *fail*
with, for example, memory-mapped capture mechanisms!

1 files changed, 32 insertions, 0 deletions

diff --git a/configure b/configure
index 43b3068a..268d487a 100755
--- a/configure
+++ b/configure
@@ -7811,6 +7811,38 @@ fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler supports the -Wcast-qual option" >&5
+$as_echo_n "checking whether the compiler supports the -Wcast-qual option... " >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_cc_force_warning_errors -Wcast-qual"
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wcast-qual"
+
+else
+
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler supports the -W option" >&5
 $as_echo_n "checking whether the compiler supports the -W option... " >&6; }
 	save_CFLAGS="$CFLAGS"