From c11be930ea2a6ab3c750f8d3fa61d38139886dd2 Mon Sep 17 00:00:00 2001
From: Marcel Holtmann <marcel@holtmann.org>
Date: Tue, 15 Jul 2014 22:18:59 +0200
Subject: [PATCH] build: Use default compiler flags

---
 acinclude.m4 | 26 ++++++++++++++++++++++++++
 configure.ac |  5 +++++
 2 files changed, 31 insertions(+)
 create mode 100644 acinclude.m4

diff --git a/acinclude.m4 b/acinclude.m4
new file mode 100644
index 00000000..f15dfd1a
--- /dev/null
+++ b/acinclude.m4
@@ -0,0 +1,26 @@
+AC_DEFUN([AC_PROG_CC_PIE], [
+	AC_CACHE_CHECK([whether ${CC-cc} accepts -fPIE], ac_cv_prog_cc_pie, [
+		echo 'void f(){}' > conftest.c
+		if test -z "`${CC-cc} -fPIE -pie -c conftest.c 2>&1`"; then
+			ac_cv_prog_cc_pie=yes
+		else
+			ac_cv_prog_cc_pie=no
+		fi
+		rm -rf conftest*
+	])
+])
+
+AC_DEFUN([COMPILER_FLAGS], [
+	if (test "${CFLAGS}" = ""); then
+		CFLAGS="-Wall -O2 -D_FORTIFY_SOURCE=2 -fsigned-char"
+	fi
+	if (test "$USE_MAINTAINER_MODE" = "yes"); then
+		CFLAGS+=" -Werror -Wextra"
+		CFLAGS+=" -Wno-unused-parameter"
+		CFLAGS+=" -Wno-missing-field-initializers"
+		CFLAGS+=" -Wdeclaration-after-statement"
+		CFLAGS+=" -Wmissing-declarations"
+		CFLAGS+=" -Wredundant-decls"
+		CFLAGS+=" -Wcast-align"
+	fi
+])
diff --git a/configure.ac b/configure.ac
index 0ffb9813..320ba81f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -14,7 +14,12 @@ AM_MAINTAINER_MODE
 
 AC_PREFIX_DEFAULT(/usr/local)
 
+COMPILER_FLAGS
+
+AC_LANG_C
+
 AC_PROG_CC
+AC_PROG_CC_PIE
 AC_PROG_INSTALL
 AC_PROG_MKDIR_P
 AC_PROG_LN_S