FALSE NEGATIVE: zerodiv misses a known zero divisor in a function template with an unknown branch condition

[Rodri]

Hi, I found a false negative in Cppcheck 2.21.0 and 2.22 dev when a constant argument makes a division inside a function-template instantiation divide by zero.

Affected tool

Cppcheck 2.21.0; also reproduced with Cppcheck 2.22 dev

Affected checker

Cppcheck CheckOther::checkZeroDivision (zerodiv / zerodivcond)

Minimal reproducer

bool unknown();

template <class T>
void divide(T value) {
  if (unknown())
    value = 1 / (value - 5);
}

void test() {
  divide<int>(5);
}

Reproduction command

cppcheck --version
cppcheck --enable=warning --std=c++17 --checkers-report=checkers.txt --template='{file}:{line}:{column}: [{id}] {message}' cppcheck-zerodiv-fn-template-unknown-branch.cpp

Current behavior

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

Expected behavior

Cppcheck should report line 6 because the instantiation receives value == 5, making value - 5 equal to zero.

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/15051