Re: [PATCH, c++ diagnostics] Fix c++ front end i18n problems

[Paolo Bonzini <bonzini at gnu dot org>]

On 12/11/2009 04:34 AM, Shujing Zhao wrote:
> >   if (!spaces)
> >     {
> >       /* String owned by the owner, it should not be freed.  */
> >       *str = NULL;
> >     }
>
> In order to print " "<repeat n times> from the second candidate at
>
> error ("%s %+#D", *str, OVL_CURRENT (fn));
>
> The *str is changed at print_overloaded_functions first. When the
> OVL_NEXT loop is over, and back to print_chained_functions, call
> print_overloaded_functions will transfer " "<repeat n times> to
> print_overloaded_functions. That is also why the argument of
> print_overloaded_functions is **str not *str.
> Since the pointer spaces and *str point the same place after assign
> spaces to *str, *str can't be assign NULL. Otherwise it will produce
> "segment fault".

Yes, understood.  I think your patch from yesterday would be almost 
okay, except for the wrong "fns == NULL_TREE && !TREE_VALUE (fns)" 
condition.  The correct one would be "fns == NULL_TREE || !TREE_CHAIN 
(fns)", I think.

However, the whole interaction between print_overloaded_functions, 
print_chained_functions and print_candidates is messy.  I tried doing it 
with a single recursive function.  Here is what it may look like:

/* Print the list of functions at FNS, going through all the overloads
   for each element of the list.  Alternatively, FNS can not be a
   TREE_LIST, in which case it will be printed together with all the
   overloads.

   MORE and *STR should respectively be 0 and point to NULL
   when the function is called from the outside.  They are used
   internally on recursive calls.  print_candidates manages the
   two parameters.  */

static void
print_candidates_1 (tree fns, int more, const char **str)
{
  tree fn;
  char *spaces = NULL;

  for (fn = fns; fn; fn = OVL_NEXT (fn))
    if (TREE_CODE (fn) == TREE_LIST)
      {
        tree fn2;
        for (fn2 = fn; fn2 != NULL_TREE; fn2 = TREE_CHAIN (fn))
          print_candidates_1 (TREE_VALUE (fn2),
                              TREE_CHAIN (fn2) || more, str);
      }
    else
      {
        if (!*str)
          {
            /* Pick the prefix string.  */
            if !more && !OVL_NEXT (fns))
              {
                error ("candidate is: %+#D", OVL_CURRENT (fn));
                continue;
              }

            *str = _("candidates are:");
            spaces = get_spaces (*str);
          }
        error ("%s %+#D", *str, OVL_CURRENT (fn));
        *str = spaces ? spaces : *str;
      }

  if (!more && spaces)
    {
      free (spaces);
      *str = NULL;
    }
}

static void
print_candidates (tree fns)
{
  char *str = NULL;
  gcc_assert (!(is_overloaded_fn (fns)
                && TREE_CODE (fns) == TREE_LIST));
  print_overloaded_functions (fns, 0, &str);
  gcc_assert (str == NULL);
}

What do you think?

Paolo