diff options
author | Keir Fraser <keir@xen.org> | 2011-05-24 08:18:42 +0100 |
---|---|---|
committer | Keir Fraser <keir@xen.org> | 2011-05-24 08:18:42 +0100 |
commit | 385a1618504e4cd55d2d99f9995a172095a30a60 (patch) | |
tree | 49640e7c63a430d3dcca06ed4fe3c73662f5fd05 | |
parent | f13f6842d5c14483dffa6a9ce9df1c750995a9e0 (diff) | |
download | xen-385a1618504e4cd55d2d99f9995a172095a30a60.tar.gz xen-385a1618504e4cd55d2d99f9995a172095a30a60.tar.bz2 xen-385a1618504e4cd55d2d99f9995a172095a30a60.zip |
Fix Config.mk's cc-option for -Wno-* options.
These disable-warning options are handled specially by GCC:
(a) they are ignored unless the compiler emits a warning; and
(b) even then they produce a warning rather than an error
To handle this, modify the test invocation of GCC to compile a
fragment of code that will always provoke a warning (integer assigned
to pointer). This works around (a) above.
Then, we grep the compiler's stdout/stderr for the option-under-test,
the presence of which would indicate an "unrecognized command-line
option" warning/error. This works around (b) above, letting us
distinguish between the "integer assigned to pointer" and
"unrecognized command-line option" warnings.
Signed-off-by: Keir Fraser <keir@xen.org>
xen-unstable changeset: 23369:37c77bacb52a
xen-unstable date: Mon May 23 17:38:28 2011 +0100
-rw-r--r-- | Config.mk | 14 |
1 files changed, 12 insertions, 2 deletions
@@ -62,9 +62,19 @@ PYTHON_PREFIX_ARG ?= --prefix="$(PREFIX)" # https://bugs.launchpad.net/ubuntu/+bug/362570 # cc-option: Check if compiler supports first option, else fall back to second. +# +# This is complicated by the fact that unrecognised -Wno-* options: +# (a) are ignored unless the compilation emits a warning; and +# (b) even then produce a warning rather than an error +# To handle this we do a test compile, passing the option-under-test, on a code +# fragment that will always produce a warning (integer assigned to pointer). +# We then grep for the option-under-test in the compiler's output, the presence +# of which would indicate an "unrecognized command-line option" warning/error. +# # Usage: cflags-y += $(call cc-option,$(CC),-march=winchip-c6,-march=i586) -cc-option = $(shell if test -z "`$(1) $(2) -S -o /dev/null -xc \ - /dev/null 2>&1`"; then echo "$(2)"; else echo "$(3)"; fi ;) +cc-option = $(shell if test -z "`echo 'void*p=1;' | \ + $(1) $(2) -S -o /dev/null -xc - 2>&1 | grep -- $(2)`"; \ + then echo "$(2)"; else echo "$(3)"; fi ;) # cc-option-add: Add an option to compilation flags, but only if supported. # Usage: $(call cc-option-add CFLAGS,CC,-march=winchip-c6) |