use configure.ac instead of configure.in

support --enable-debug to switch on picky compiler options

ares/configure.ac

+dnl Process this file with autoconf to produce a configure script.
+AC_INIT(ares_init.c)
+
+AC_PROG_CC
+AC_PROG_INSTALL
+AC_PROG_RANLIB
+
+AC_CANONICAL_HOST
+case $host_os in
+solaris*)
+	AC_DEFINE(ETC_INET)
+	;;
+esac
+
+AC_SEARCH_LIBS(gethostbyname, nsl)
+AC_SEARCH_LIBS(socket, socket)
+
+dnl ************************************************************
+dnl lame option to switch on debug options
+dnl
+AC_MSG_CHECKING([whether to enable debug options])
+AC_ARG_ENABLE(debug,
+AC_HELP_STRING([--enable-debug],[Enable pedantic debug options])
+AC_HELP_STRING([--disable-debug],[Disable debug options]),
+[ case "$enableval" in
+  no)
+       AC_MSG_RESULT(no)
+       ;;
+  *)   AC_MSG_RESULT(yes)
+
+    CPPFLAGS="$CPPFLAGS -DCURLDEBUG"
+    CFLAGS="$CFLAGS -g" 
+    if test "$GCC" = "yes"; then
+       CFLAGS="$CFLAGS -W -Wall -Wwrite-strings -pedantic -Wno-long-long -Wundef -Wpointer-arith -Wnested-externs"
+
+       dnl here's a more aggressive set to use:
+       dnl CFLAGS="$CFLAGS -W -Wall -Wwrite-strings -pedantic -Wno-long-long -Wundef -Wpointer-arith -Wnested-externs -Wcast-align -Winline -Wstrict-prototypes -Wmissing-declarations -Wmissing-prototypes -Wshadow -Wfloat-equal -Wsign-compare -Wunreachable-code"
+    fi
+    dnl strip off optimizer flags
+    NEWFLAGS=""
+    for flag in $CFLAGS; do
+      case "$flag" in
+      -O*)
+        dnl echo "cut off $flag"
+        ;;
+      *)
+        NEWFLAGS="$NEWFLAGS $flag"
+        ;;
+      esac
+    done
+    CFLAGS=$NEWFLAGS
+       ;;
+  esac ],
+       AC_MSG_RESULT(no)
+)
+
+AC_OUTPUT(Makefile)

ares/configure.in

-dnl Process this file with autoconf to produce a configure script.
-AC_INIT(ares_init.c)
-
-AC_PROG_CC
-AC_PROG_INSTALL
-AC_PROG_RANLIB
-
-AC_CANONICAL_HOST
-case $host_os in
-solaris*)
-	AC_DEFINE(ETC_INET)
-	;;
-esac
-
-AC_SEARCH_LIBS(gethostbyname, nsl)
-AC_SEARCH_LIBS(socket, socket)
-
-AC_OUTPUT(Makefile)