c/1027: slightly misleading printf format warning

[Joseph S. Myers]

On 10 Dec 2000, Gabriel Dos Reis wrote:

> I've already put in the necessary machinery for so doing in
> diagnostics.*.  What remains to be done is to replace error_with_decl()
> and warning_with_decl() to error() and warning() (maybe error_at())
> with use of those specifiers.  That was planed but I didn't get the
> chance to finish the work.  Already on my TODO list but I would love
> to assist any taker.

What's also needed for the present PR is for the code in cp/error.c for
formatting types to move to common code where C can use it as well.  (I'd
guess that most of it can probably be shared, though stylistic differences
such as "int*" for C++ versus "int *" for C should be allowed for.  Or, a
version covering only C types might be a lot simpler.)  The existing code
in c-lang.c

    case 'D':
    case 'F':
    case 'T':
      {
        const char *n = DECL_NAME (t)
          ? (*decl_printable_name) (t, 2)
          : "({anonymous})";
        output_add_string (buffer, n);
      }
      return 1;

along with the default decl_printable_name / decl_name doesn't seem
adequate for even the simple case of this PR (where a name for a pointer
type should be constructed).

-- 
Joseph S. Myers
jsm28@cam.ac.uk