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

[Vasiliy Korchagin]

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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: allow-non-int-main-option.patch
Type: text/x-patch
Size: 3095 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20120213/364fa20a/attachment.bin>