PATCH: skipping code in gengtype (trunk)

[Basile STARYNKEVITCH]

Le Thu, Jan 04, 2007 at 07:16:26AM -0800, Ian Lance Taylor écrivait/wrote:
> Basile STARYNKEVITCH <basile@starynkevitch.net> writes:
> 
> > In some occasions [1,2], the gengtype generator behave strangely, and
> > a simple workaround would be to let it skip (i.e. ignore) some code.
> > 
> > The attached patch (to rev.120437 of trunk) includes into gengtype the
> > ability to skip code, and documents it.
> > 
> > [1] http://gcc.gnu.org/ml/gcc/2007-01/msg00172.html
> > [2] http://gcc.gnu.org/ml/gcc/2003-03/msg01258.html
> 
> I don't understand how adding the ability to for gengtype to skip some
> code actually fixes these problems.  If you want to put something on
> the heap, gengtype needs to understand what it is.


I just wanted an explicitly managed (hence heap allocated, but not
garbage collected) vector of char* (file paths which are explicitly
strdup-ed). I'm only interested by the VEC API and I don't want ggc or
GTY to know about it - there is no garbage collectable pointers in my
example. In that case, my patch is a suitable workaround (for an
example like [1]).

What I don't understand in the first place is why the example in [1]
don't work (ie why gengtype produces an error). I do admit that my
patch is just a quick and dirty work-around and not a fix, but
apparently it works.

Apparently I might do 

	typedef void* basilevoid_p;
	VEC(basilevoid_p,heap) *basilevoid_vector;

since the free_block_data field in struct dom_walk_data in
gcc/domwalk.h is declared similarily (but this file domwalk.h does not
at all use GTY so is not processed by gengtype).

But it seems difficult to mix heap-allocated (hence explicitly
allocated & freed) vectors of heap allocated pointers (eg.strdup-ed
strings) and GTY-ed vectors in the same file.

Maybe I should use the "none" allocation and code instead for the
example [1]  
  typedef char* basilestring_t;
  DEF_VEC_P (basilestring_t);
  DEF_VEC_ALLOC_P (basilestring_t,none);
  static VEC(basilestring_t,none) *basilestring_vector;
but the comment in gcc/vec.h says
                                       The ALLOC argument specifies the
   allocation strategy, and can be either 'gc' or 'heap' for garbage
   collected and heap allocated respectively.  It can be 'none' to get
   a vector that must be explicitly allocated (for instance as a
   trailing array of another structure). 

I don't understand if an explicitly allocated VEC pointer of strdup-ed
char* pointers fits into this case.

So I only want to have a VEC of char*, each vector element being an
strdup-ed string. I want to explicitly allocate the vector and each of
it elements, and will explicitly deallocate each element and the whole
vector itself

Regards.
-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/ 
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359 
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