On 6/30/23 15:13, Dan Carpenter wrote:
So here we have:
if (u32_val > SOMETHING) {
The condition is impossible when the code is compiled on a 64-bit
system
This is exactly what the compilers warns about:
$ cat test.c
#include <stdint.h>
int f (int *p, unsigned n)
{
return n > SIZE_MAX / sizeof (*p);
}
$ gcc -Wextra -c test.c
test.c: In function ‘f’:
test.c:5:12: warning: comparison is always false due to limited range of data type [-Wtype-limits]
5 | return n > SIZE_MAX / sizeof (*p);
| ^
$ gcc -m32 -Wextra -c test.c
$ clang -Wextra -c test.c
test.c:5:12: warning: result of comparison of constant 4611686018427387903 with expression of type 'unsigned int' is always false [-Wtautological-constant-out-of-range-compare]
return n > SIZE_MAX / sizeof (*p);
~ ^ ~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
$ clang -m32 -Wextra -c test.c
$
Where is a bug here? What the compiler developers are intended to fix?
How the compilers should behave in this case?
Dmitry
