Re: C++ Darwin Port BUG in source code

[Marcin Dalecki <martin at dalecki dot de>]

On 2005-02-06, at 22:22, Andrew Pinski wrote:

> On Feb 6, 2005, at 4:10 PM, Marcin Dalecki wrote:
> > I wonder why the corresponding pargma unused implementation in 
> > darwin-c.c is calling c_lex() and similar functions, which appear at
> > least to be C code dependant. However strictly adhering to the advice 
> > the attached patch should at least give proper semantics then.
> > <lookup_name.diff>
>
> Call c_lex is fine, if you look at the file c-pragma.c which is for 
> both the C and C++
> front-ends.
>
> What I would do instead of this (semi) huge patch is to make 
> lookup_name in the C++
> correspond to C prototype and change the C++ front-end to use a newer 
> function
> for the old lookup_name.

Please look a bit closer. It's the C++ part which gets an additional 
parameter to
differentiate the name lookup scope (namespace type or else). The code 
there is indeed a
bit fussy and I don't think it would be easy to tackle with it. In esp. 
the last
parameter there is decoded by the following one-shoot "function" - code 
placed in a
function called only once it's a function for me it's just an elaborate 
notation:

/* Combine prefer_type and namespaces_only into flags.  */

static int
lookup_flags (int prefer_type, int namespaces_only)
{
  if (namespaces_only)
    return LOOKUP_PREFER_NAMESPACES;
  if (prefer_type > 1)
    return LOOKUP_PREFER_TYPES;
  if (prefer_type > 0)
    return LOOKUP_PREFER_BOTH;
  return 0;
}


and then

flags |= lookup_flags(prefer_type, namespace_only);


But just:

 if (namespaces_only)
    flags |= LOOKUP_PREFER_NAMESPACES;
  if (prefer_type > 1)
    flags |= LOOKUP_PREFER_TYPES;
  if (prefer_type > 0)
    flags |= LOOKUP_PREFER_BOTH;

Would do it as well. And then it becomes really obvious that the logics 
is
a bit wired. We stuff known information in to flags to decode the same 
information
multiple times later on. Pretty sure a sign that the information passed 
in first place
is not encoded in the most convenient way. For me the problem is thus 
on the hand of C++.