[ovs-dev] [sFlow 2/7] Move C compiler warning (-W) flags from CFLAGS to AM_CFLAGS.

Ben Pfaff blp at nicira.com
Thu Nov 19 21:48:58 UTC 2009


C compiler warning options added by the "configure" script have until
now been put into CFLAGS.  However that option is supposed to be reserved
for the user under Automake rules, so move them to AM_CFLAGS.

Besides increased adherence to Automake rules, this is useful because
AM_CFLAGS can be overridden on a per-target (e.g. program or library)
basis, whereas CFLAGS cannot.  In turn, building the sFlow library (which
will be added in an upcoming commit) requires overriding the compiler
flags to avoid some warning messages.  (By modifying the warning flags, we
avoid the need to modify the sFlow library in any way.)
---
 Makefile.am  |    1 +
 acinclude.m4 |    5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index add0e72..de51e10 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -16,6 +16,7 @@ AM_CPPFLAGS += -I $(top_srcdir)/include
 AM_CPPFLAGS += -I $(top_srcdir)/lib
 
 AM_CFLAGS = -Wstrict-prototypes
+AM_CFLAGS += $(WARNING_FLAGS)
 
 if NDEBUG
 AM_CPPFLAGS += -DNDEBUG
diff --git a/acinclude.m4 b/acinclude.m4
index 767414e..e37a316 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -230,8 +230,9 @@ AC_DEFUN([OVS_CHECK_CC_OPTION],
 
 dnl OVS_ENABLE_OPTION([OPTION])
 dnl Check whether the given C compiler OPTION is accepted.
-dnl If so, add it to CFLAGS.
+dnl If so, add it to WARNING_FLAGS.
 dnl Example: OVS_ENABLE_OPTION([-Wdeclaration-after-statement])
 AC_DEFUN([OVS_ENABLE_OPTION], 
-  [OVS_CHECK_CC_OPTION([$1], [CFLAGS="$CFLAGS $1"])])
+  [OVS_CHECK_CC_OPTION([$1], [WARNING_FLAGS="$WARNING_FLAGS $1"])
+   AC_SUBST([WARNING_FLAGS])])
 dnl ----------------------------------------------------------------------
-- 
1.6.3.3





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