[cfe-commits] [LLVMdev] clang errors on void main()

[David Blaikie]

2012/2/9 Vasiliy Korchagin <korchagin at ispras.ru>:
> On 08.02.2012 23:47, David Blaikie wrote:
>
> On Wed, Feb 8, 2012 at 11:25 AM, Chris Lattner <clattner at apple.com> wrote:
>
> On Feb 8, 2012, at 5:31 AM, Vasiliy Korchagin wrote:
>
> 07.02.2012 07:27, Eli Friedman пишет:
>
> On Mon, Feb 6, 2012 at 6:51 PM, Xin Tong<xerox.time.tech at gmail.com>  wrote:
>
> Is there any way to stop this ?
>
> /home/socrates/llvm/llvm-3.0.src/benchmarks/powerstone/crc/crc.c:67:1:
> error: 'main' must return 'int'
> void main()
> ^
> 1 error generated.
>
> You mean besides fixing the source of your benchmark so it's valid C?
> Not at the moment... patches welcome.
>
> -Eli
>
> We suggest patch for allowing main() function to have non-integer return
> type. This feature can be enabled with "-allow-non-int-main" option. In this
> case warning about incorrect main() return type will be printed instead of
> error.
>
> In patch also included test case for this feature.
>
> Vasiliy Korchagin,
>
> Hi Vasiliy,
>
> Please send clang patches to cfe-dev.
>
> or even cfe-commits (further instructions are here:
> http://clang.llvm.org/get_involved.html)
>
> [I've dropped llvm-dev and added cfe-commits to this email]
>
> My first thought based on your description alone would be that we
> should support this, if at all, probably in the way that GCC already
> does - surfacing non-int returning main as a warning in C (under
> -Wmain) and error in C++ (as it is already) if that's practical.
>
> & looking at the patch itself: Your change is even more permissive
> than GCC (when you use the flag you've added) allowing C++ to have
> void returning main. I don't see any need to be so accepting.
>
> (& the change you've made in Sema::ActOnFinishFunctionBody scares me a
> bit - what does that do when you have int returning main but you turn
> this flag on? not allow implicit return 0? that seems problematic)
>
> - David
>
> David, thanks for your reply.
>
> Seems like my response missed mailing list, so I'm sending it again.
> I changed the patch and now "-allow-non-int-main" option allows to print
> a warning in C and error in C++ in case of non-integer main. I also
> fixed implicit returning 0.

Sorry, I just didn't get around to replying - I still think this
should be under the -Wmain flag, probably - like it is in GCC. But I
could be wrong - hopefully someone else pipes up with an opinion too.

(it's possible it should be stronger - perhaps a separate warning that
defaults to error - but I don't think it should be an entirely
new/separate flag)

- David