Re: Attributes

[Sean Hunt <rideau3 at gmail dot com>]

On 07/10/2010 03:56 PM, Ian Lance Taylor wrote:
> Sean Hunt<rideau3@gmail.com>  writes:
>
> >      void foo () __attribute__((noreturn)); // right per spec
> >      void foo __attribute__((noreturn)) (); // works
> >      __attribute__((noreturn)) void foo (); // works
> >
> > It's obvious that the first example of each kind (noreturn appearing
> > after the function declarator) must be accepted if it's a GCC
> > attribute and not if it's a C++0x attributes. The later two (noreturn
> > appearing before the declaration or after the identifier) must be
> > accepted for C++0x attributes, but it's not clear if the GCC syntax
> > being accepted is an accident or by design.
>
> As far as I can see they are both documenated as working at
> http://gcc.gnu.org/onlinedocs/gcc-4.5.0/gcc/Attribute-Syntax.html , so I
> think it is by design.

The problem is that it is not clear if that is intended, or merely an 
accident. The spec is rather unclear about a number of things.

> > Is anyone currently working on C++0x attributes in GCC and, if not, is
> > there anyone who can help me through what we should and shouldn't
> > accept in clang?
>
> I don't know the answer to this.  It's clear that C++0x attributes are
> not the same as GNU attributes.
>
> Ian

Yes. I'm trying to determine which parts of GCC attributes are merely 
accidents and don't really need implementation, as there are a lot of 
situations where GCC attributes (as implemented) are significantly more 
liberal than C++0x attributes are. This will be an issue that GCC 
developers will encounter when an effort is made to implement 
attributes; I would like to see what discussion can be had before I go 
ahead and reimplement the attribute codepaths within clang.

Sean