fix broken fuzz target compile_parse_tree

[lucasbalieiro]

closes #161

updates the outdated fuzz target compile_parse_tree.
It was still using named::to_commit_node, which has since been replaced by named::forget_names (see this commit)

Also (as suggested in the issue discussion):

• removed fuzz from the exclude list in Cargo.toml and add to workspace members
• added a CI job to cargo check the fuzz crate

[apoelstra]

Nice, thanks!! Code review ACK -- running through my local CI and also Github CI will run. Hopefully it passes. Stuff like this is often really annoying to get right..

[apoelstra]

@lucasbalieiro ok, this isn't working for me with my local crate2nix setup, because when I run cargo test ignoring the test = false lines in Cargo.toml, this runs the fuzzer indefinitely without end. (The fact that this happens is probably a bug in crate2nix, but okay.)

I would like you to remove all the test = false etc lines from Cargo.toml and make sure you can run cargo test and have it terminate in finite time.

The most straightforward thing might be to just copy all the boilerplate from rust-simplicity. e.g. https://github.com/BlockstreamResearch/rust-simplicity/blob/master/fuzz/fuzz_targets/c_rust_merkle.rs

In particular the actual fuzz target should be gated on cfg(fuzzing), and we need to add

[lints.rust]
unexpected_cfgs = { level = "deny", check-cfg = ['cfg(fuzzing)'] }

to fuzz/Cargo.toml.

[lucasbalieiro]

@apoelstra sorry for the delay, I’m traveling at the moment.

In 881f454, I applied the same style you suggested in rust-simplicity to all our fuzz_targets.

Now, when you ignore test = false, cargo test should no longer run indefinitely.

[apoelstra]

No worries. I have been traveling too.

Can you re-arrange these commits (using git rebase -i is easiest) so that the "add fuzz to the workspace members table" commit comes last? That way each individual commit will work for me.

[lucasbalieiro]

No worries. I have been traveling too.

Can you re-arrange these commits (using git rebase -i is easiest) so that the "add fuzz to the workspace members table" commit comes last? That way each individual commit will work for me.

done! commits re-arranged