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

[Vasiliy Korchagin]

13.02.2012 12:28, Vasiliy Korchagin пишет:
> 13.02.2012 05:39, Chandler Carruth пишет:
>> On Sun, Feb 12, 2012 at 6:17 AM, Vasiliy Korchagin 
>> <korchagin at ispras.ru <mailto:korchagin at ispras.ru>> wrote:
>>
>> On 12.02.2012 07:39, Chandler Carruth wrote:
>>> On Sat, Feb 11, 2012 at 5:31 AM, Vasiliy Korchagin
>>> <korchagin at ispras.ru <mailto:korchagin at ispras.ru>> wrote:
>>>
>>> I agree, without setting implicit return zero bit changes in
>>> codegen are not necessary. New version of patch is attached.
>>>
>>>
>>> The warning you're adding, as David suggested, should be under a
>>> separate flag.
>>>
>>> It should also be an extwarn as this is technically a language
>>> extension, and it should be enabled by default (you may already
>>> have that, just want it clarified).
>>>
>>> --- a/lib/Sema/SemaDecl.cpp
>>> +++ b/lib/Sema/SemaDecl.cpp
>>> @@ -5795,8 +5795,13 @@ void Sema::CheckMain(FunctionDecl* FD,
>>> const DeclSpec& DS) {
>>> const FunctionType* FT = T->getAs<FunctionType>();
>>> if (!Context.hasSameUnqualifiedType(FT->getResultType(),
>>> Context.IntTy)) {
>>> - Diag(FD->getTypeSpecStartLoc(), diag::err_main_returns_nonint);
>>> - FD->setInvalidDecl(true);
>>> + if (getLangOptions().C99) {
>>> + // In C we allow main() to have non-integer return type.
>>> + Diag(FD->getTypeSpecStartLoc(),
>>> diag::warn_main_returns_nonint);
>>>
>>> If you want this to be enabled in all C modes, you should accept
>>> more than just C99: "!getLangOptions().CPlusPlus" is a good
>>> candidate here.
>>>
>>> @@ -7204,7 +7209,8 @@ Decl *Sema::ActOnFinishFunctionBody(Decl
>>> *dcl, Stmt *Body,
>>> if (FD->isMain()) {
>>> // C and C++ allow for main to automagically return 0.
>>> // Implements C++ [basic.start.main]p5 and C99 5.1.2.2.3.
>>> - FD->setHasImplicitReturnZero(true);
>>> + if (!getLangOptions().C99)
>>> + FD->setHasImplicitReturnZero(true);
>>>
>>> This isn't correct. You need to be checking for a non-int return
>>> type here, not for C99. If the function has an int return type we
>>> want the implicit return zero.
>> Now new warning is under the separate flag ("-Wmain-return-type")
>> and it is an extwarn and it is enabled by default. Also problems
>> with C modes and implicit return zero are fixed. New patch is
>> attached.
>>
>>
>> This is super close. Two minor nits, and it should be good-to-go:
>>
>> 1) The canonical prefix for an ExtWarn diagnostic is "ext_", not 
>> "warn_".
>>
>> 2) I would name the test something more generic so we can fold more 
>> main tests into this file. 'main.c' would be fine.
> Warning prefix is changed and test is renamed.
>
> Vasiliy Korchagin,
> The Institute for System Programming of the Russian Academy of Sciences
>
>
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> cfe-commits at cs.uiuc.edu
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Sorry, last time patch was incorrect. Now it is ok.

- Vasiliy
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