An inconsistent behaviour in EXPENSIVE_LOOP_INVARIANT_CALL detector

[stoneman258]

I discovered an inconsistency in the EXPENSIVE_LOOP_INVARIANT_CALL detector. In the following code example, Infer reports a warning of this type at line 22, but no warnings at line 23, despite both lines being semantically equivalent. This indicates an inconsistent bug in the detection logic.

import java.util.ArrayList;

public class Main {
    int incr(int x) {
        return x + 1;
    }

    void foo1(ArrayList<Integer> list) {
        int x = 0;
        for (Integer elem : list) {
            incr(x);
        }
    }

    void foo2(ArrayList<Integer> list) {
        int x = 0;
        list.forEach(elem -> incr(x)); 
    }

    void func(int size, ArrayList<Integer> list) {
        for (int i = 0; i < size; i++) {
            foo1(list); // report an EXPENSIVE_LOOP_INVARIANT_CALL warning
            foo2(list); // report no warnigns 
        }
    }
}