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| author | Michal Marek <mmarek@suse.cz> | 2011-05-02 12:51:15 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-26 09:10:36 -0800 |
| commit | f4cf7f671c87c93233386fab0d70db807dc1b5ac (patch) | |
| tree | 9be554404a04370bb15e1dd858d3eff599472c4f | |
| parent | 85c269fa465918e1ba4668cf8c04de68e7b2298d (diff) | |
| download | lwn-f4cf7f671c87c93233386fab0d70db807dc1b5ac.tar.gz lwn-f4cf7f671c87c93233386fab0d70db807dc1b5ac.zip | |
kbuild: Fix passing -Wno-* options to gcc 4.4+
commit 8417da6f2128008c431c7d130af6cd3d9079922e upstream.
Starting with 4.4, gcc will happily accept -Wno-<anything> in the
cc-option test and complain later when compiling a file that has some
other warning. This rather unexpected behavior is intentional as per
http://gcc.gnu.org/PR28322, so work around it by testing for support of
the opposite option (without the no-). Introduce a new Makefile function
cc-disable-warning that does this and update two uses of cc-option in
the toplevel Makefile.
Reported-and-tested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 12 | ||||
| -rw-r--r-- | Makefile | 4 | ||||
| -rw-r--r-- | scripts/Kbuild.include | 5 |
3 files changed, 19 insertions, 2 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 71c602d61680..ab8689b94d65 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -502,6 +502,18 @@ more details, with real examples. gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used. Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options + cc-disable-warning + cc-disable-warning checks if gcc supports a given warning and returns + the commandline switch to disable it. This special function is needed, + because gcc 4.4 and later accept any unknown -Wno-* option and only + warn about it if there is another warning in the source file. + + Example: + KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) + + In the above example, -Wno-unused-but-set-variable will be added to + KBUILD_CFLAGS only if gcc really accepts it. + cc-version cc-version returns a numerical version of the $(CC) compiler version. The format is <major><minor> where both are two digits. So for example @@ -538,7 +538,7 @@ KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) endif # This warning generated too much noise in a regular build. -KBUILD_CFLAGS += $(call cc-option, -Wno-unused-but-set-variable) +KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls @@ -568,7 +568,7 @@ CHECKFLAGS += $(NOSTDINC_FLAGS) KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,) # disable pointer signed / unsigned warnings in gcc 4.0 -KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,) +KBUILD_CFLAGS += $(call cc-disable-warning, pointer-sign) # disable invalid "can't wrap" optimizations for signed / pointers KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow) diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index c67e73ecd5be..92b62a8db0f8 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -118,6 +118,11 @@ cc-option-yn = $(call try-run,\ cc-option-align = $(subst -functions=0,,\ $(call cc-option,-falign-functions=0,-malign-functions=0)) +# cc-disable-warning +# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable) +cc-disable-warning = $(call try-run,\ + $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -xc /dev/null -o "$$TMP",-Wno-$(strip $(1))) + # cc-version # Usage gcc-ver := $(call cc-version) cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC)) |