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| author | Keir Fraser <keir@xen.org> | 2011-05-23 17:38:28 +0100 |
|---|---|---|
| committer | Keir Fraser <keir@xen.org> | 2011-05-23 17:38:28 +0100 |
| commit | 28f8fb7d2b3fde2f5cbe5526ac4f1c932e3f5d26 (patch) | |
| tree | 6cab52be55a7f2c38f5a4719f6dc94ec9e47b6e7 /Config.mk | |
| parent | 5a40af4739c1402ada1a8668c1a08c4ce6a1628f (diff) | |
| download | xen-28f8fb7d2b3fde2f5cbe5526ac4f1c932e3f5d26.tar.gz xen-28f8fb7d2b3fde2f5cbe5526ac4f1c932e3f5d26.tar.bz2 xen-28f8fb7d2b3fde2f5cbe5526ac4f1c932e3f5d26.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>
Diffstat (limited to 'Config.mk')
| -rw-r--r-- | Config.mk | 14 |
1 files changed, 12 insertions, 2 deletions
@@ -71,9 +71,19 @@ 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) |