[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: GCC 7 warnings
Re: GCC 7 warnings
Sat, 9 Sep 2017 11:27:40 -0700
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1
Eli Zaretskii wrote:
Paul, why do we use level 5 here, instead of using level 3, the
default? Level 3 supports the /* FALLTHROUGH */ and similar comments
that indicate a fall-through in a more portable way.
Those comments have problems of their own, as they don't play well with macros
and with non-GCC auditing tools that look at preprocessor output. So in other
GNU projects we use level 5. It's easy enough to use it portably, and we've done
that elsewhere in Emacs with the FALLTHROUGH macro. I just never noticed
tparam.c since I never compiled it. I fixed it just now.
Many of the problems you ran into are because of my 2016-05-30 patch "Omit
IF_LINT code that no longer seems needed" that simplified the code by assuming a
recent-enough GCC for --enable-gcc-warnings.
There is a tradeoff for --enable-gcc-warnings. If we try to support ancient GCC
compilers, we'll have to complicate the code and consume scarce maintenance
resources. If we support only the latest GCC, developers using slightly-older
GCCs will get some annoying warnings when they use --enable-gcc-warnings. I
prefer to push the bleeding edge here, and ask developers who use
--enable-gcc-warnings to at most (say) a year-old GCC version, as this saves
some work for the rest of us. Of course we can't expect everybody to immediately
sync to the latest GCC when released, but on the other hand there is a cost to
supporting too-old GCCs, a cost I'd rather not pay (since I bear a good deal of
By the way, I find the UNINIT macro to be more readable than supplying nonce
expressions, as UNINIT clearly indicates to the reader that the variable is
intended to be uninitialized. So I used that as part of my fixups. The
pre-2016-05-30 version of the code was using UNINIT anyway.
- GCC 7 warnings, Eli Zaretskii, 2017/09/09
- Re: GCC 7 warnings,
Paul Eggert <=