FALSE POSITIVE: `zerodiv` ignores a nonzero constraint through an alias

[Rodri]

Hi, I found a false positive in Cppcheck 2.21.0 when equivalent pointer expressions constrain an aliased divisor to be nonzero.

Affected tool

Cppcheck 2.21.0

Affected checker

Cppcheck zerodiv

Minimal reproducer

int divide_after_alias_check(void *data) {
  int *value = (int *)data;
  *value = 0;
  if (*(int *)data == 0)
    return 0;
  return 1 / *value;
}

Reproduction command

cppcheck --version
cppcheck --enable=warning --std=c11 --checkers-report=checkers.txt --template='{file}:{line}:{column}: [{id}] {message}' cppcheck-zerodiv-fp-alias-constraint.c

Current behavior

Cppcheck reports cppcheck-zerodiv-fp-alias-constraint.c:6:12: [zerodiv] Division by zero.

Expected behavior

Cppcheck should not report zerodiv. The final return is reached only when *(int *)data != 0, and value points to that same object.

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/15003