c/6980: -Wbad-function-cast gives bogus warning for (double) rand()

[richdawe@bigfoot.com]

>Number:         6980
>Category:       c
>Synopsis:       -Wbad-function-cast gives bogus warning for (double) rand()
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jun 10 01:56:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Richard Dawe
>Release:        gcc 3.1
>Organization:
>Environment:
DJGPP ports of gcc 3.1 & binutils 2.11.2, DJGPP CVS, running on Windows 98 SE
>Description:
Here is a simple test case:

---Start program---
#include <limits.h>
#include <stdlib.h>

int
main (void)
{
  double d;

  d = (double) rand() / RAND_MAX;

  return(EXIT_SUCCESS);
}
---End program---

I compile the program like this and get the following warnings:

bash-2.04$ gcc -Wall -Wbad-function-cast -c a.c
a.c: In function `main':
a.c:9: warning: cast does not match function type

rand is defined in <stdlib.h> like this:

int     rand(void);

Since an integer can fit into a double, I don't understand why this code gives a warning. We've discussed the warning on djgpp-workers@delorie.com and most people think it's a bug.

Thank you for your time. Regards, Richard Dawe
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: