https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115647
Bug ID: 115647
Summary: No warning when a loop is infinite due to type of
operand in conditional
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Target Milestone: ---
A user sent in this report, noting that it might not be in scope for the
analyzer:
SUBJECT:
Wanalyzer-infinite-loop: Add warning for counter unable to ever not meet
condition in `for` loop
COMMENT:
In the below `for` statement, the `char` counter `i` has a smaller range
than the value of the `int` condition `n` (in this case 500) hence it will
overflow and wrap around when incremented beyond its max range value (in
this case 127) before reaching that value, resulting in an infinite loop.
#include <stdio.h>
int
main (void)
{
char i;
const int n = 500;
for (i = 0; i < n; ++i)
printf ("%d\n", i);
return 0;
}
Using -Wall, -pedantic, -Wconversion and -fanalyzer on gcc 14.1 doesn't
warn about anything for this infinite loop. Maybe this is something
-Wanalyzer-infinite-loop should warn about.
