ANSI C -> non-ANSI C

[Chip Salzenberg]

According to rfg at NCD.COM (Ron Guilmette):
>What I have always planned on doing (if I ever get the time) is to simply
>add another (optional) warning to GCC which would warn you about all
>actual parameters to (prototyped) functions which get an implicit change
>of representation by virtue of being passed into a formal parameter of
>a sufficiently different type to require such a change of representation.

Such a warning is too lax.  You need warnings wherever a parameter
value, after default promotions of char->int, short->int,
float->double, etc., is not of the *exact* same type as the prototyped
parameter.

I would make two exceptions to the above rule.  Character pointers
and void pointers are guaranteed by the standard always to have the
same representation, so we can consider them to be equivalent for
purposes of parameter passing.  A similar guarantee exists about the
signed and unsigned variants of integral types, so they also may be
considered identical.

As an example, one machine (VAX) provides int and long types with the
same representation, whereas the next machine ('286 large model) does
not.  Passing "0" for a long parameter thus will require a "(long)"
cast for complete equivalence without prototypes, no matter which
machine you happen to be using to run GCC.

If the aim is to provide prototype-free code that works just like the
prototyped code, then the warning must be based on portability, not a
particular machine's data representation.
-- 
Chip Salzenberg at Teltronics/TCT     <chip at tct.uucp>, <uunet!pdn!tct!chip>
      "I'm really sorry I feel this need to insult some people..."
            -- John F. Haugh II    (He thinks HE'S sorry?)