From: horst DOT kraemer AT gmx DOT de (Horst Kraemer)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Conversion warnings
Date: Thu, 10 Aug 2000 06:34:55 GMT
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To: djgpp AT delorie DOT com
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On Wed, 09 Aug 2000 19:19:02 -0400, "Lets Go Canes!"
<LetsGoCanes AT webmail DOT bellsouth DOT net> wrote:

> While compiling a program, I am getting some strange
> conversion warnings - I have -Wconversion enabled
> intentionally to catch unintended conversions.
> 
> The following short sample will demonstrate:
> 
> ----------
> void    f(float, char);
> 
> int main(void)
> {
>     float   x;
>     char    c;
> 
>     x = 22.0 / 7.0;
>     c = '*';
>     
>     f(x, c);
>     return 1;
> 
> }
> ----------
> 
> When compiled, it gives the following output:
> 
> gcc -Wconversion -c test.c
> test.c: In function `main':
> test.c:11: warning: passing arg 1 of `f' as `float' rather than `double' due to prototype
> test.c:11: warning: passing arg 2 of `f' with different width due to prototype
 
> Any ideas?

The problem is that -Wconversion doesn't do what you think it does.
Please read the documentation. It says that -Wconversions warns if the
handling of the parameter would be different for a function *without*
prototype.

Thus, if you would pass your arguments to a function declared as

     void ff();

then for ff(x,c) the first parameter 'x' would be converted to double
and the second parameter 'c' would be converted to 'int'. As you have
a prototyped function f and x,c exactly match the definition of the
prototype for f the handling of the parameters is *different* from the
handling for the call of ff. This is probably not useful for your
purpose but that's how it is defined.


Regards
Horst