This patch seems bigger than it needs to be. Can we isolate the change to this single function?

We could, but it would mean that literally every run would need to go through the libtest harness. I thought every runs did, but then saw in the bolero source code that there’s a BOLERO_LIBTEST_HARNESS environment variable, so I considered it’s not actually the case?

(Also, I thought maybe libfuzzer also needs to be able to run executables without going through the libtest harness, eg. in the dataflow things, but I have literally no idea how those works so I wrote the patch only so it doesn’t newly break stuff, at the expense of maybe not fixing them if they were already broken)

That said if bolero fuzzers always run through the libtest harness I could at least slightly simplify the patch :)

I've opened #176 as a more minimal change. The BOLERO_LIBTEST_HARNESS environment variable is just to detect if we're using libtest or not. If we're not, it would look something like:

fn main() {
    bolero::check!().for_each(|_| { });
}

Which means we still go through bolero's harness. But it'll only execute a single harness in this mode.