[file-roller] activate compiler warnings

[Paolo Bacchilega <paobac src gnome org>]

commit 1ceb60e36079e1337aed053b62d327bc2e89fafc
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Mon Jun 18 20:47:28 2012 +0200

    activate compiler warnings

 configure.ac |   22 +++++++++++++++++++++-
 1 files changed, 21 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index b9e56df..c662093 100644
--- a/configure.ac
+++ b/configure.ac
@@ -60,6 +60,26 @@ fi
 
 dnl ===========================================================================
 
+WARN_CFLAGS="-Wall -Wcast-align -Wtype-limits -Wclobbered -Wempty-body -Wignored-qualifiers"
+
+for option in $WARN_CFLAGS; do
+	SAVE_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $option"
+	AC_MSG_CHECKING([whether gcc understands $option])
+	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[]])],[has_option=yes],[has_option=no])
+	if test x$has_option = xyes; then
+		WARNINGS="$WARNINGS $option"
+	fi
+	AC_MSG_RESULT($has_option)
+	CFLAGS="$SAVE_CFLAGS"
+	unset has_option
+	unset SAVE_CFLAGS
+done
+unset option
+CFLAGS="$CFLAGS $WARNINGS"
+
+dnl ===========================================================================
+
 AC_ARG_ENABLE([run_in_place],
 	      AS_HELP_STRING([--enable-run-in-place],
 			     [load ui data and extensions from source tree]),,
@@ -186,7 +206,7 @@ dnl ******************************
 AC_CONFIG_FILES([Makefile
 		 file-roller.spec
 		 data/Makefile
-		 data/file-roller.desktop.in		 
+		 data/file-roller.desktop.in
 		 data/icons/Makefile
 		 data/icons/16x16/Makefile
 		 data/icons/16x16/actions/Makefile