Messages in this thread | | | From | Arnd Bergmann <> | Date | Wed, 10 May 2017 21:32:36 +0200 | Subject | Re: Updating kernel.org cross compilers? |
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On Wed, May 10, 2017 at 3:40 PM, Segher Boessenkool <segher@kernel.crashing.org> wrote: > Hi Arnd, long time no see, > > On Wed, May 10, 2017 at 09:58:13AM +0200, Arnd Bergmann wrote: >> >> So in addition to GCC 7.1 I'd like to have at least GCC 6.3 around, >> >> which builds kernels without warnings today. >> > >> > If you don't want warnings, turn off the warnings or just don't look at >> > them... or fix the problems? Many of the new warnings point out actual >> > problems. >> > >> > Many of those sprintf problems in the kernel have already been fixed. >> >> I've been using gcc-7.0 for a long time and fixed a lot of bugs it found, >> along with more harmless warnings, but I had disabled a couple of >> warning options when I first installed gcc-7 and ended up ignoring >> those. >> >> The exact set of additional options I used is: >> >> -Wimplicit-fallthrough=0 -Wno-duplicate-decl-specifier >> -Wno-int-in-bool-context -Wno-bool-operation -Wno-format-truncation >> -Wno-format-overflow >> >> there were a couple of others that I sent kernel fixes for instead. >> I should probably revisit that list and for each of them either >> only enable it with "make W=1" or fix all known warnings. >> In the long run, I'd actually hope to fix all W=1 warnings too >> and enable them by default. > > Most of those usually point out actual problems (at least code that > isn't as clear as it should be). I do hate that first one though.
My point is that we have others in W=1 some of which are equally useful: warning-1 := -Wextra -Wunused -Wno-unused-parameter warning-1 += -Wmissing-declarations warning-1 += -Wmissing-format-attribute warning-1 += $(call cc-option, -Wmissing-prototypes) warning-1 += -Wold-style-definition warning-1 += $(call cc-option, -Wmissing-include-dirs) warning-1 += $(call cc-option, -Wunused-but-set-variable) warning-1 += $(call cc-option, -Wunused-const-variable) warning-1 += $(call cc-disable-warning, missing-field-initializers) warning-1 += $(call cc-disable-warning, sign-compare)
I've looked through arm and x86 gcc-7 allmodconfig builds (without my longish fixup series) again and found these added warnings compared to gcc-6.3.1 overall:
2 -Werror=bool-operation 4 -Werror=maybe-uninitialized 1 -Werror=parentheses 2 -Werror=stringop-overflow= 2 -Werror=tautological-compare
I probably submitted patches for those in the past, will have another look to see if I need to resubmit them, or if some of them might be regressions.
148 -Werror=duplicate-decl-specifier
Only a few files are affected, I can take care of fixing them all:
| 1 arch/arm/mach-at91/pm.c | 1 arch/arm/mach-bcm/bcm_kona_smc.c | 1 arch/arm/mach-cns3xxx/core.c | 1 arch/arm/mach-omap2/prm_common.c | 1 arch/arm/mach-omap2/vc.c | 1 arch/arm/mach-spear/time.c | 2 drivers/input/keyboard/cros_ec_keyb.c | 4 sound/soc/codecs/rt5514.c | 136 sound/soc/codecs/rt5665.c
89 -Werror=int-in-bool-context
This showed up in 26 files in allmodconfig alone. I had started on some of them but given up at some point. I can certainly submit the ones I did already, but probably won't have the patience to address all of them myself.
54 -Werror=format-overflow=
Same here.
494 -Werror=format-truncation=
These are all over the place, in 187 files.
The last one in particular seems less useful than -Wformat-security which we already disable (for all levels), and I'd rather have them both in "make W=1". For -Wint-in-bool-context and -Wformat-overflow= it's less obvious whether we should try to get them all fixed quickly, using >100 patches or put them into W=1 along with -Wformat-truncation.
Arnd
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