Silently checking whether diagnostics would occur

[Joseph S. Myers]

On Thu, 14 Sep 2000, Kaveh R. Ghazi wrote:

> One nit with passing in a function is that attribute printf doesn't
> work on function pointers IIRC, so all the calls to the warning
> function ptr would lose format checks.  (Though I suppose that could
> be fixed.)  Sigh, that would have been cleaner since I could do

This should probably be considered a bug (which should be fixed) that
format attributes don't attach properly to the function type.

Marc Espie's __attribute__((__nonnull__)) patch allows (I think) for one
function to have multiple printf/scanf attributes (which could make sense
if all but as must one are vprintf/vscanf-like), but I don't know if it
fixes this problem.

> I'll look into passing in an int*, then I guess all calls to warning()
> would instead be:
> 
>  > if (foo)
>  >   {*foo = 1; return;}
>  > else
>  >   warning ("blah blah", arg1, arg2);
> 
> Although I appreciate now the reasons against using a global var, I
> also see maintenance problems down the road ensuring that one always
> uses the above idiom when adding new format checks.
> 
> Any ideas on making it more automatic and less dependent on good
> behavior?  Since `warning' is a varargs function, for portability
> reasons I can't make the above snippet a macro.

I'd suggest making this into a format_warning function (taking the int *
and the normal warning() parameters).  Remember the calls from tfaff() and
maybe_read_dollar_number() and finish_dollar_format_checking() and adjust
the parameters of these functions to include the int *, and note that
format checking is not presently reentrant because of static variables
used in the $ format checking (I've added reentrancy to my TODO list).

In addition, -pedantic should not affect code generation, so before
calling the format checking the value of `pedantic' should be saved and it
should be set to some known value (I suggest 1).

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