Q51620: No Warning When Passing Long to Int Prototyped Function

Article: Q51620
Product(s): See article
Version(s): 5.10   | 5.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | s_quickc s_quickasm | mspl13_c
Last Modified: 21-MAR-1990

If you prototype a function to accept an integer, and then pass a long
integer to the function, Microsoft C Version 5.01 and Microsoft QuickC
Versions 1.00, 1.01, 2.00, and 2.01 fail to give a warning about the
data conversion if the value being passed is between -65536 and
+65535. Instead, the value is converted to a valid integer (between
-32768 and 32767) and passed to the function, causing unexpected
results.

This is also a problem with the Microsoft QuickAssembler Version 2.01.

The following code demonstrates this problem:

#include <stdio.h>

void func(int,int);

void main(void)
{
     func(50000L,1L);    /* Can also pass in (long)50000,long(1)     */
}                        /* and have no warnings.                    */
                         /* Try changing to 100000, notice correct   */
                         /* warning.                                 */
void func(int a, int b)
{
     printf("a=%d  b=%d",a,b);
}

If you declare two long integers and pass them to func, as in the
following, you receive a data conversion warning as expected:

   long a=50000,b=1;
   func(a,b);

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