FALSE NEGATIVE: Division-by-zero checking misses a divisor constrained by a switch case

[Rodri]

Hi, I found a false negative in Cppcheck 2.21.0 when a switch case constrains the divisor to zero.

Affected tool

Cppcheck 2.21.0

Affected checker

Cppcheck CheckOther::checkZeroDivision (zerodiv / zerodivcond)

Minimal reproducer

int divide_in_zero_case(int value) {
  switch (value) {
  case 0:
    return 1 / value;
  default:
    return 0;
  }
}

Reproduction command

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

Current behavior

Cppcheck produces neither a zerodiv nor a zerodivcond diagnostic. The checker report lists CheckOther::checkZeroDivision as active.

Expected behavior

Cppcheck should report a division-by-zero diagnostic at line 4 because the case 0 branch executes the division with value == 0.

[CHR]

See https://trac.cppcheck.net/ticket/10