[cfe-dev] Chrome/mac is all-clang, all-the-time

[Ruben Van Boxem]

2011/11/1 Matthieu Monrocq <matthieu.monrocq at gmail.com>

> Le 1 novembre 2011 00:03, Miles Bader <miles at gnu.org> a écrit :
>
> 2011/11/1 Chandler Carruth <chandlerc at google.com>:
>> > I'm really sorry that came off as condescending, it wasn't meant to be.
>> The
>> > cost imposed by switching to Clang's error messages was one we took very
>> > seriously. Working with GCC for a long time isn't a negative statement
>> about
>> > the developer, it's a simple reality given the long history GCC has in
>> the
>> > open source community as essentially the only compiler option available.
>>
>> Er, well you basically divided your user base into two categories:
>> those who eagerly embraced clang, and those who were too
>> dim/rigid/inexperienced to appreciate it -- with what seems to be the
>> implication that anybody in the former group _must_ be in the latter.
>> That's veering pretty close to True Scotsman territory...
>>
>> While I'm sure both types of user are present, I suspect that you're
>> omitting another group:  those who don't really care so much either
>> way -- especially amongst those whose compiler usage doesn't usually
>> tickle the particularly egregious cases (e.g. C developers -- like
>> Gnome! -- and C++ devs who aren't pushing boundaries with templates),
>> and developers who are experienced enough (as I imagine most google
>> devs to be!) that they aren't particularly bothered by the specific
>> wording of error messages...
>>
>> Again, I don't want to seem like I'm speaking _against_ clang -- I'm
>> not, I use it, and I like it -- and clang certainly does generally
>> have pretty clear error messages.  But there seems to be this idea
>> floating around that gcc's error messages are unusably bad, and that
>> clang's are in a completely different class, and _that_ I just don't
>> see.
>>
>> [I should note, btw, that gcc is developed too -- and that includes
>> improving the error messages, and compilation speed...]
>>
>> -miles
>>
>> --
>> Cat is power.  Cat is peace.
>>
>>
> Hello,
>
> I think you misunderstood Chandler's statement here. From the way I read
> it (but then, I am a French speaker first and foremost...) it seemed to me
> that some people were rightly concerned about the lack of productivity that
> would result from having to learn the "clang" way. I think it's a valid
> concern.
>
> Personally, I have been using Clang at home for a while, and gcc at work
> (company policy) and I will fully admit that despite my real interest in
> Clang and its definitely better diagnosis, I am simply more used to gcc's
> diagnostics and thus more adept at deciphering them, no matter how arcane
> they may appear to a beginner...
>
> Another interesting point though, for the switch, is the performance of
> the resulting binary. Development is one thing, and we have a lot of tools
> at our disposal to help out: compiling with both Clang and gcc with
> warnings on certainly help catch a lot of errors, static analysis is quite
> useful as well, debug builds etc... However when pushing software to a
> server, we still want to heck out as much speed and as few memory as we can
> from it.
>
> As far as I know, gcc still has the lead here (but then the only serious
> benchmarks I saw were from phoronix, and it was a while ago). I seem to
> remember that LLVM was more adept for numerical computation, but it's of
> little interest to me (and my company). If someone had accurate figures
> Clang 3.0 / gcc 4.7, it would be interesting to see how it falls out now.
>

+1: The only "up-to-date" comparisons one can find are Mac GCC 4.2.1 vs
current LLVM/Clang, but never really trustable comparisons vs more recent
GCC versions. It would also be very informative and perhaps have the most
value as a "reality-check" if the by now dated comparisons here:
http://clang.llvm.org/features.html#performance could be updated to compare
current GCC vs current Clang. I'm expecting the difference to be reduced
(GCC has improved lot since 4.2(!).. duh!). Running the exact same
benchmarks and comparing Clang's and GCC's progress would be very good to
know and perhaps point out any (if there are any) weaknesses in Clang's
performance.

Ruben


> --Matthieu
>
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