Bug in b88: Stack Overflow when changing a Supplier to a lambda using LazySeq

[Samir Talwar]

I wrote some code using the LazySeq library (
https://github.com/nurkiewicz/LazySeq ) which implements merge sort
given two already-sorted lists. It crashes with a stack overflow.

That works well. If I try and use lambdas, javac crashes with a stack overflow.

Lambdas code (MergeSortCrashing.java):

    public static <T extends Comparable<T>> LazySeq<T>
mergeSorted(LazySeq<T> a, LazySeq<T> b) {
        if (a.isEmpty()) {
            return b;
        }

        if (b.isEmpty()) {
            return a;
        }

        if (a.head().compareTo(b.head()) <= 0) {
            return LazySeq.cons(a.head(), () -> mergeSorted(a.tail(), b));
        } else {
            return LazySeq.cons(b.head(), () -> mergeSorted(a, b.tail()));
        }
    }

This is attempting to build against b88. Crashes in both IntelliJ and Maven.

Two things: if an explicit comparator is passed in rather than having
T be Comparable, it works. (See attachment: MergeSortSafe.java). It
also works if I replace the lambdas with explicit instantiations of
Supplier<LazySeq<T>> (see MergeSortWithoutLambdas.java).

I'm pretty sure this is a bug. I hope this is the right place to
report it. Cheers for all your hard work, guys. I hope this one gets
fixed soon.

— Samir.