"Joseph S. Myers" <[email protected]> a écrit:
> On Wed, 22 Jan 2014, Prathamesh Kulkarni wrote:
>
>> Unfortunately, I am not clear on how to check for format specifiers in
>> string.
>> Should I do it manually by checking the format string for specifiers
>> and call abort if found a no-argument specifier,
>> or is there a better way to do it ?
>
> I'll leave it to Dodji as diagnostics maintainer to advise on the best way
> to implement error_at_no_args.
Thanks for the heads-up, Joseph.
Assuming we want to do something more than just segfaulting if
error_at_no_args is given a format specifier that needs an argument, I
think the function pretty-print.c:pp_format is the place where the
core of the change has to be done. Basically, that function walks the
format string and expands format specifiers.
Thus, in that function, if a format specifier needs an argument (that
is, each time we try to access text->args_ptr) but we are in a context
where we want to accept only no-argument specifiers, we can call abort
or internal_error with a meaningful error message.
I guess we can assume that we know that we are in a
oo-argument-specifier context if text->args_ptr is NULL in pp_format()
That text->args_ptr is actually the va_ap that you (Prathamesh) set to
NULL when you did:
void
error_at_no_args (location_t loc, const char *gmsgid)
{
diagnostic_info diagnostic;
diagnostic_set_info (&diagnostic, gmsgid, NULL, loc, DK_ERROR);
^^^^
^
|
here: __|
report_diagnostic (&diagnostic);
}
And then, just keep the error_at_no_args() implementation like what
you did already.
Also, you'd need to modify cp/error.c:cp_printer in a similar way, to
issue an internal_error each time we try to access a null test->args_ptr.
But then, I guess some people might argue that we could as well let
the code as is and just segfault on accessing a NULL test->args_ptr.
I would personally lean towards aborting with a meaningful error
message, but I'd like to hear what others think about this.
I hope this helps.
--
Dodji
