Possible accidental mutation

[GTRI-nathan]

Hi, first off, very cool library & benchmarks!

I'm not sure if I'm doing something wrong or making an incorrect assumption, but I think I've found a bug causing accidental mutation in List in 0.2.0-alpha6, see my minifed reproducer:

import io.lacuna.bifurcan.List;

public class Test {
        public static void main(String args[]) {
                int size = 32;
                List<Integer> a = new List<Integer>();
                List<Integer> b = new List<Integer>();
                for (int i = 0; i < size; i++) {
                        a = a.addLast(1);
                        b = b.addLast(1);
                }
                List<Integer> ap = a.set(15, 2);
                List<Integer> bp = b.set(15, 2);
                List<Integer> z = null;
                // Comment out, and the equals is true
                z = ap.set(15, 3);
                System.out.println("a: " + a);
                System.out.println("b: " + b);
                System.out.println("ap:" + ap);
                System.out.println("bp:" + bp);
                System.out.println("z: " + z);
                System.out.println("Should be true: " + ap.equals(bp));
        }
}

Will print:

~/test ➜ javac -cp "./bifurcan-0.2.0-alpha6.jar" Test.java && java -cp ".:./bifurcan-0.2.0-alpha6.jar" Test
a: [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
b: [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
ap:[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
bp:[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
z: [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
Should be true: false

Commenting out the z = ap.set(15,3); line, or changing the size to anything less than 32 will make the result true.

[ztellman]

Hmm, that does look like a bug, especially the magic length of 32. Let me take a look.

…

On Mon, Jul 12, 2021 at 10:15 AM, GTRI-nathan ***@***.***> wrote: Hi, first off, very cool library & benchmarks! I'm not sure if I'm doing something wrong or making an incorrect assumption, but I think I've found a bug causing accidental mutation in List in 0.2.0-alpha6, see my minifed reproducer: import io.lacuna.bifurcan.List; public class Test { public static void main(String args[]) { int size = 32; List<Integer> a = new List<Integer>(); List<Integer> b = new List<Integer>(); for (int i = 0; i < size; i++) { a = a.addLast(1); b = b.addLast(1); } List<Integer> ap = a.set(15, 2); List<Integer> bp = b.set(15, 2); List<Integer> z = null; // Comment out, and the equals is true z = ap.set(15, 3); System.out.println("a: " + a); System.out.println("b: " + b); System.out.println("ap:" + ap); System.out.println("bp:" + bp); System.out.println("z: " + z); System.out.println("Should be true: " + ap.equals(bp)); } } Will print: ~/test ➜ javac -cp "./bifurcan-0.2.0-alpha6.jar" Test.java <http://test.java/> && java -cp ".:./bifurcan-0.2.0-alpha6.jar" Test a: [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] b: [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] ap:[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] bp:[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] z: [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1] Should be true: false Commenting out the z = ap.set(15,3); line, or changing the size to anything less than 32 will make the result true. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#36>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAHUP746AYEFUAQWYTN5S3TXMPLHANCNFSM5AHIKWNQ> .