assert statement containing switch expression is not decompiled correctly

CFR version

CFR 0.151-SNAPSHOT (7b97993)

Compiler

javac 14.0.1

Description

assert statements containing switch expressions (and maybe other complicated constructs as well) are not decompiled correctly. Instead of emitting an assert, CFR emits a read of a variable called $assertionsDisabled, which does not exist.

Example

Source:

class AssertTest {
    void test(Integer i) {
        assert switch (i + 1) {
            case 1 -> true;
            default -> false;
        } : switch (i + 2) {
            case 1 -> "1";
            default -> "2";
        };
    }
    
    void test2(int i) {
        assert i != 2 : "Test";
    }
}

Decompiled output:

class AssertTest {
    AssertTest() {
    }

    void test(Integer n) {
        if (!$assertionsDisabled) {
            switch (n + 1) {
                case 1: {
                    break;
                }
                default: {
                    throw new AssertionError((Object)(switch (n + 2) {
                        case 1 -> "1";
                        default -> "2";
                    }));
                }
            }
        }
    }

    void test2(int n) {
        assert (n != 2) : "Test";
    }
}

[leibnitz27]

BTW - I used to get this one a little wrong, also fixed - but this produces amusing results in FF 😉

class AssertTest21 {

    private static boolean absolutelyVitalFunction(int x) {
        System.out.println("Disable the reactor");
        return true;
    }

    private static boolean checkCheeseSupply() {
        System.out.println("We've got cheese");
        return true;
    }

    public static void stopTheMeltdown(Integer x) {
        if (absolutelyVitalFunction(x)) {
            assert (checkCheeseSupply());
        }
    }
}

[leibnitz27]

Oh, how gross is it that you can now write this:

class SwitchExpressionAssert1f {
    void test(Integer i) {
        assert switch (i + 1) {
            default -> { System.out.println("Uh oh");
            if (i == 3) {
                assert(false); // <--- look ma nested assert.
            }
            if (i < 10) yield true;
            yield true;
            }
        };
    }
}