From: Yao Qi <qiyaoltc@gmail.com>
To: Tom Tromey <tom@tromey.com>
Cc: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>
Subject: Re: [RFA 1/3] Fix "fall through" comments
Date: Fri, 30 Sep 2016 21:09:00 -0000 [thread overview]
Message-ID: <CAH=s-PPVvkcc5yvZa4VwDtLJ3pGs5tqK7MbrPxsUFQNQ-yoVsw@mail.gmail.com> (raw)
In-Reply-To: <8760pfhjhl.fsf@tromey.com>
On Wed, Sep 28, 2016 at 9:12 PM, Tom Tromey <tom@tromey.com> wrote:
>>>>>> "Yao" == Yao Qi <qiyaoltc@gmail.com> writes:
>
> Tom> On my machine, clang won't build gdb. From memory there was at
> Tom> least some issue compiling .c files in c++ mode, but I think there
> Tom> were other problems as well.
>
> Yao> We can use option '-x c++' to suppress the warnings, but you are
> Yao> right, there are some other problems, like some warning options are
> Yao> unknown to clang.
>
> Yeah. I tried it again and there are two issues.
>
> First, clang++ doesn't like the .c extension:
>
> clang-3.8: error: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated
>
> I was able to fix this with:
>
> make CC=clang CXX='clang++ -x c++' CC_LD=clang++
>
> After that I got:
>
> error: unknown warning option '-Wunused-but-set-parameter'; did you mean '-Wunused-parameter'? [-Werror,-Wunknown-warning-option]
> error: unknown warning option '-Wunused-but-set-variable'; did you mean '-Wunused-const-variable'? [-Werror,-Wunknown-warning-option]
>
> This is probably an oversight in warning.m4, as in config.log I see:
>
> configure:14316: clang++ -c -g -O2 -Wunused-but-set-parameter conftest.cpp >&5
> warning: unknown warning option '-Wunused-but-set-parameter'; did you mean '-Wunused-parameter'? [-Wunknown-warning-option]
> 1 warning generated.
> configure:14316: $? = 0
>
> Adding 'WERROR_CFLAGS=' solves this... but at this point it's fine to
> keep fall-through comments, because warnings are disabled anyway.
>
> It's worth noting that I see tons of "unused function" warnings from
> vec.h. when building this way. There's definitely some work to be done
> here if anybody wants to use clang.
>
Yes, I see all of them above in my build.
> In sum my view is that it's fine to go ahead with the comment approach.
OK.
> If someone wants to fix up the clang build I can help convert the
> comments to an attribute. (The issue with doing it up-front is
> discovering the spots that would need a change -- gcc won't tell us what
> they are.)
>
Agreed. Your patch is good to me then.
--
Yao (齐尧)
next prev parent reply other threads:[~2016-09-30 19:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 18:16 [RFA 0/3] Fix some -Wimplicit-fallthrough warnings Tom Tromey
2016-09-27 18:16 ` [RFA 1/3] Fix "fall through" comments Tom Tromey
2016-09-27 21:48 ` Yao Qi
2016-09-27 21:53 ` Tom Tromey
2016-09-28 21:51 ` Yao Qi
2016-09-28 21:58 ` Tom Tromey
2016-09-30 21:09 ` Yao Qi [this message]
2016-09-27 18:16 ` [RFA 2/3] Add missing ATTRIBUTE_NORETURNs Tom Tromey
2016-09-28 7:28 ` Yao Qi
2016-09-28 17:40 ` Tom Tromey
2016-09-28 17:41 ` Yao Qi
2016-09-27 18:52 ` [RFA 3/3] Fix "obvious" fall-through warnings Tom Tromey
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