Messages in this thread | | | Date | Thu, 7 Jan 2016 18:07:43 -0800 | From | Brian Norris <> | Subject | Re: Build failure: -Wno-unused-const-variable DNE on old GCC |
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On Fri, Jan 08, 2016 at 12:31:54PM +1100, Ian Munsie wrote: > Excerpts from Brian Norris's message of 2016-01-08 10:02:25 +1100: > > > - It forces cxl developers to a higher standard. cxl has already had > > > more than it's fair share of incredibly difficult to debug issues, > > > so any way we can reduce the risk of errors going in makes our lives > > > (and our end-users lives) better. > > > > One problem with this point: not all warnings are under the purview of > > cxl developers. For instance, if I turn up warning verbosity (W=1), then
(BTW, I think most of these files are currently clean with W=1, but not W=2)
> > the *header* files start producing plenty of warnings. Should this break > > the build? Your code didn't change, and you can't fix those errors. > > That's a good point, but the specific warnings that we suppressed in the > new compiler are in drivers/misc/cxl/cxl.h, which is an internal header > that should only ever be included by the cxl driver. We do have some > headers elsewhere which are included by other drivers, the generic ppc > architecture code and userspace, but these are all warning free and > won't be affected by the -Werror when included from elsewhere.
I was referring to when extra warnings are turned on, not just the default. So this fails spectacularly:
$ export ARCH=powerpc $ make ppc64_defconfig $ make drivers/misc/cxl/api.o W=2 CC [M] drivers/misc/cxl/api.o In file included from include/linux/bitops.h:36:0, from include/linux/kernel.h:10, from include/linux/list.h:8, from include/linux/pci.h:25, from drivers/misc/cxl/api.c:10: ./arch/powerpc/include/asm/bitops.h:226:94: error: declaration of 'ffs' shadows a built-in function [-Werror=shadow] In file included from include/linux/atomic.h:562:0, from include/linux/mutex.h:18, from include/linux/kernfs.h:13, from include/linux/sysfs.h:15, from include/linux/kobject.h:21, from include/linux/pci.h:28, from drivers/misc/cxl/api.c:10: include/asm-generic/atomic-long.h: In function 'atomic_long_read_acquire': include/asm-generic/atomic-long.h:45:231: error: nested extern declaration of '__compiletime_assert_45' [-Werror=nested-externs] In file included from include/linux/atomic.h:562:0, from include/linux/mutex.h:18, from include/linux/kernfs.h:13, from include/linux/sysfs.h:15, from include/linux/kobject.h:21, from include/linux/pci.h:28, from drivers/misc/cxl/api.c:10: include/asm-generic/atomic-long.h: In function 'atomic_long_set_release': include/asm-generic/atomic-long.h:57:1: error: nested extern declaration of '__compiletime_assert_57' [-Werror=nested-externs] In file included from include/linux/ktime.h:25:0, from include/linux/rcupdate.h:47, from include/linux/idr.h:18, from include/linux/kernfs.h:14, from include/linux/sysfs.h:15, from include/linux/kobject.h:21, from include/linux/pci.h:28, from drivers/misc/cxl/api.c:10: include/linux/jiffies.h: In function 'jiffies_to_timespec': include/linux/jiffies.h:422:131: error: declaration of 'jiffies' shadows a global declaration [-Werror=shadow] include/linux/jiffies.h:78:65: error: shadowed declaration is here [-Werror=shadow] In file included from include/linux/kernfs.h:16:0, from include/linux/sysfs.h:15, from include/linux/kobject.h:21, from include/linux/pci.h:28, from drivers/misc/cxl/api.c:10: [...many more failures...] cc1: all warnings being treated as errors make[1]: *** [drivers/misc/cxl/api.o] Error 1 make: *** [drivers/misc/cxl/api.o] Error 2
I doubt you plan to fix all those. So making -Werror configurable seems like the only way forward, then. (Glad you agreed!)
Regards, Brian
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