Re: gcc-in-cxx: Garbage Collecting STL Containers

[Taras <taras dot judge at shaw dot ca>]

Daniel Berlin wrote:
> Maybe at some point then we should just stop using gengtype and just
> hand-write the walkers once.
>
> One of the reasons gengtype exists is because you can't easily have an
> abstract interface with member functions that you can force people to
> implement in C.
>
> In C++, we can.
>
> This is of course, a large change, but i'm not sure how much more work
> it really is than trying to understand gengtype and rewrite it to
> properly parse C++/support STL containers.
>   
I might be the only person out there who likes GTY annotations. The fact 
that gengtype has a separate parser is highly inconvenient. Why not use 
the GCC C/C++ parser on gengtype? It seems that with some refactoring, 
it should be possible to bootstrap just the C++ parser( without memory 
management or maybe some  minimal handwritten stuff).
Then the parser could parse the headers to extract GTY annotations with 
full semantic info.
For my plugin stuff I use a macro to convert GTY stuff to GNU 
attributes(patch is coming as soon as I get the paperwork done) which 
allows me to do some trivial metaprogramming to produce useful things 
such generate most of the code for a JavaScript binding to GIMPLE gcc 
plugin(http://developer.mozilla.org/en/docs/Treehydra).
Overall I think the the GTY annotations make the structs more 
understandable and the fact that they allow for generating 
structure-aware code is awesome. I think there may be other automation 
benefits to be reaped from GTY-style annotations elsewhere in the code, 
so the system should be improved, not canned.

Taras
> On Wed, Jun 25, 2008 at 10:49 AM, Tom Tromey <tromey@redhat.com> wrote:
>   
> > > > > > > "Daniel" == Daniel Jacobowitz <drow@false.org> writes:
> > > > > > >               
> > > > On Wed, Jun 25, 2008 at 08:35:41AM -0600, Tom Tromey wrote:
> > > > I think most of the needed changes will be in gengtype.  If you aren't
> > > > familiar with what this does, read gcc/doc/gty.texi.
> > > >         
> > Daniel> Also - I may regret saying this but - doesn't gengtype have a
> > Daniel> simplistic C parser in it?  How upset is it likely to get on C++
> > Daniel> input?
> >
> > Yeah, it does -- see gengtype-parse.c.
> > I haven't done extensive hacking there; I don't really know how upset
> > it will be.  I assume it won't work the first time :)
> >
> > Tom
> >
> >