On 09/13/2018 12:03 PM, Fabian Groffen wrote: > On 13-09-2018 07:36:09 -0400, Richard Yao wrote: >> >> >>> On Sep 12, 2018, at 6:55 PM, Thomas Deutschmann <whi...@gentoo.org> wrote: >>> >>>> On 2018-09-12 16:50, Rich Freeman wrote: >>>> There is also the case where we want these warnings to block >>>> installation, because the risk of there being a problem is too great. >>> >>> I really disagree with that. So many devs have already said multiple >>> times in this thread that "-Werror" is only turning existing warnings >>> into fatal errors but "-Werror" itself doesn't add any new checks and >>> more often requires "-O3" to be useful. >> The way that compilers work is that the warnings are generated in the front >> end while the optimization level affects the backend. That means that -O3 >> has no effect on the code that does error generation. This remark about -O3 >> being needed to make -Werror useful is just plain wrong. > > Huh? -O3 enables more checks, which can generate more warnings. -O3 > isn't "needed", but if upstream is so interested in clean and correct > code, they should've fixed all warnings in the first place and thus > enabled all of them.
That wasn't how I read this:
> Also, consider that for -Werror to be "better", you also need -O3 in
order to activate the "proper" compiler checks like "variable set but
never used" ones.
But I'll accept that I misunderstood.
> In fact, I expect every sane upstream to use "-O3
> -Wall -Werror" in one of their automated builds. Not that this catches
> anything useful on x86{,_64} when there is for instance use of signed
> and unsigned char types, so it isn't conclusive.
>
> The whole point in here is that -Werror doesn't add much if you care.
> The whole point why it is not desired in Gentoo is that users don't
> necessarily are developers, or even interested in fixing warnings --
> regardless whether they point to real problems or not.
>
> If there are real problems in a package (exposed by a compiler or not)
> then this should ideally stand out during ~arch testing, or even before
> when the Gentoo maintainer examines the build (might even use -Werror
> for his own purposes). If such code ends up in stable arch we just made
> a stabilisation mistake, or got royally messed up by upstream, depending
> how you look at it.
>
> Fabian
>
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