Messages in this thread | | | Date | Thu, 7 Jan 2016 15:02:25 -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 09:51:35AM +1100, Daniel Axtens wrote: > > > Alternatively, remove the -Werror. We occasionally get people that add this > > flag to a Makefile, but it tends to cause more trouble whenever a new > > gcc version arrives.
^^ Your reasons below don't really address this point. No matter how well you patch a later kernel release, you can't fix a problem in an existing kernel release that is triggered by a new warning in a new compiler. This shouldn't cause a build failure.
> Speaking up as the person who added -Werror to cxl, I'd really rather > it stayed. There are a number of reasons I think this. Here's the first > three that came to mind. > > - cxl is powerpc specific (and always will be for deep seated hardware > reasons), and is handled through the powerpc tree. arch/powerpc > compiles with -Werror, and as part of the powerpc ecosystem, cxl > should too. > > - 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 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 is a real use case for me daily: I turn the warning verbosity up on my compile tests, then (smart)diff the build logs before and after new patches. That way, I can see what new warnings (even potentially false positive ones) are introduced. I can't do that if every random developer wants to stick -Werror in their Makefile.
> - I am (and I'm quite confident the other cxl people are) quite happy to > send patches to fix build-breaking issues such as this. Indeed, I > would have, except you sent it during the Australian night :) > > If it's really super-duper important we can consider putting it behind a > config guard, but I'd really rather not.
I think there are plenty of reasons to either remove -Werror, or make it configurable. Some of them are detailed above.
Maybe you can gate the -Werror on CONFIG_PPC_WERROR, just like the rest of PowerPC?
Brian
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