Do not enable _FORTIFY_SOURCE without optimization

With glibc-2.16, using -D_FORTIFY_SOURCE requires that optimization (-O)
be used or it will prodice a warning message. Enable -Werror in our
test for _FORTIFY_SOURCE support to catch when a users specifies CFLAGS
without optimization.

The line to set CFLAGS="" when no CFLAGS are specified (either due to
being unset or geniunely empty) is required as autoconf will use
"-O2 -g" for its tests by defult when CFLAGS is unset, but will not add
them to the CFLAGS used...

Signed-off-by: Allan McRae <allan@archlinux.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 5483ee15..7fe696a9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -66,6 +66,11 @@ LT_INIT
 LIB_VERSION=`expr lib_current - lib_age`.lib_age.lib_revision
 LIB_VERSION_INFO="lib_current:lib_revision:lib_age"
 
+# Respect empty CFLAGS during compiler tests
+if test "x$CFLAGS" != "x"; then
+  CFLAGS=""
+fi
+
 # Set subsitution values for version stuff in Makefiles and anywhere else,
 # and put LIB_VERSION in config.h
 AC_SUBST(LIB_VERSION)