From a486c845b86af76bc2cd2b12c732be0d217d628a Mon Sep 17 00:00:00 2001
From: Pierre-Luc Beaudoin <pierre-luc@pierlux.com>
Date: Mon, 9 Mar 2009 00:37:15 +0200
Subject: [PATCH] Build with warning flags

---
 champlain/Makefile.am | 14 ++++++++--
 configure.ac          |  2 ++
 m4/acinclude.m4       | 65 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 m4/acinclude.m4

diff --git a/champlain/Makefile.am b/champlain/Makefile.am
index 7b5ac39..3d37e60 100644
--- a/champlain/Makefile.am
+++ b/champlain/Makefile.am
@@ -70,8 +70,18 @@ libchamplain_includedir = $(includedir)/libchamplain-0.3/champlain
 
 libchamplain_0_3_la_LDFLAGS = -version-info $(LIBRARY_VERSION)
 
-AM_CPPFLAGS = $(DEPS_CFLAGS) -DDATADIR=\""$(datadir)"\" -I$(top_srcdir)/tidy -I$(top_srcdir) -DCHAMPLAIN_COMPILATION
-AM_LDFLAGS = $(DEPS_LIBS) -export-symbols-regex ^champlain_.*
+AM_CPPFLAGS = 				\
+	$(DEPS_CFLAGS)			\
+	-DDATADIR=\""$(datadir)"\"	\
+	-I$(top_srcdir)/tidy		\
+	-I$(top_srcdir)			\
+	-DCHAMPLAIN_COMPILATION 	\
+	$(WARN_CFLAGS)
+
+AM_LDFLAGS = 				\
+	$(DEPS_LIBS)			\
+	-export-symbols-regex		\
+	^champlain_.*
 
 svgdir = $(datadir)/champlain
 svg_DATA = error.svg
diff --git a/configure.ac b/configure.ac
index 98cd746..7bef2b5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -14,6 +14,7 @@ AM_PROG_LIBTOOL
 
 # Checks for programs.
 AC_PROG_CC
+AM_PROG_CC_C_O
 AC_PATH_PROG([GLIB_GENMARSHAL], [glib-genmarshal])
 
 # Checks for libraries.
@@ -39,6 +40,7 @@ PKG_CHECK_MODULES(DEPS,
 )
 # check for gtk-doc
 GTK_DOC_CHECK(1.9)
+IDT_COMPILE_WARNINGS
 
 # -----------------------------------------------------------
 # Enable debug
diff --git a/m4/acinclude.m4 b/m4/acinclude.m4
new file mode 100644
index 0000000..18cf7c8
--- /dev/null
+++ b/m4/acinclude.m4
@@ -0,0 +1,65 @@
+dnl Turn on the additional warnings last, so -Werror doesn't affect other tests.
+
+AC_DEFUN([IDT_COMPILE_WARNINGS],[
+   if test -f $srcdir/autogen.sh; then
+	default_compile_warnings="error"
+    else
+	default_compile_warnings="no"
+    fi
+
+    AC_ARG_WITH(compile-warnings,
+                AS_HELP_STRING([--with-compile-warnings=@<:@no/yes/error@:>@],
+                               [Compiler warnings]),
+                [enable_compile_warnings="$withval"],
+                [enable_compile_warnings="$default_compile_warnings"])
+
+    warnCFLAGS=
+    if test "x$GCC" != xyes; then
+	enable_compile_warnings=no
+    fi
+
+    warning_flags=
+    realsave_CFLAGS="$CFLAGS"
+
+    case "$enable_compile_warnings" in
+    no)
+	warning_flags=
+	;;
+    yes)
+	warning_flags="-Wall -Wunused -Wmissing-prototypes -Wmissing-declarations"
+	;;
+    maximum|error)
+	warning_flags="-Wall -Wunused -Wmissing-prototypes -Wmissing-declarations -Wchar-subscripts -Wnested-externs -Wpointer-arith"
+	CFLAGS="$warning_flags $CFLAGS"
+	for option in -Wno-sign-compare -Wno-pointer-sign -Wformat; do
+		SAVE_CFLAGS="$CFLAGS"
+		CFLAGS="$CFLAGS $option"
+		AC_MSG_CHECKING([whether gcc understands $option])
+		AC_TRY_COMPILE([], [],
+			has_option=yes,
+			has_option=no,)
+		CFLAGS="$SAVE_CFLAGS"
+		AC_MSG_RESULT($has_option)
+		if test $has_option = yes; then
+		  warning_flags="$warning_flags $option"
+		fi
+		unset has_option
+		unset SAVE_CFLAGS
+	done
+	unset option
+	if test "$enable_compile_warnings" = "error" ; then
+	    warning_flags="$warning_flags -Werror"
+	fi
+	;;
+    *)
+	AC_MSG_ERROR(Unknown argument '$enable_compile_warnings' to --enable-compile-warnings)
+	;;
+    esac
+    CFLAGS="$realsave_CFLAGS"
+    AC_MSG_CHECKING(what warning flags to pass to the C compiler)
+    AC_MSG_RESULT($warning_flags)
+
+    WARN_CFLAGS="$warning_flags"
+    AC_SUBST(WARN_CFLAGS)
+])
+
-- 
2.39.5