Conversation

Apr 5, 2021

Is there a

tool (possibly rustfmt) that can sort modules with some sort of stable ordering? Would like to apply that to some generated code (from prost-build in this case)

Replying to

and

AFAIK it does this by default:

github.com

rustfmt/Configurations.md at master · rust-lang/rustfmt

Format Rust code. Contribute to rust-lang/rustfmt development by creating an account on GitHub.

Tony "Abolish ICE" Arcieri

Replying to

and

By "sort modules with some sort of stable ordering", I didn't mean "mod" statements, I meant all of the code contained within a particular module, including struct definitions, enum definitions, and their associated impl blocks

Replying to

and

Ah gotcha. I'm seeing an option you could use to kinda do that, but it's marked unstable sadly.

Replying to

and

i might be misunderstanding it, but it sounds like that option would only apply rustfmt to certain sections of the file?

Replying to

and

Yes. If your module is an entire file, then that's easy to do. It's a bit more tricky to run it on a sub module. But if you've generated that yourself, I think it's doable

Replying to

and

hmm, i think i've misunderstood what

@bascule

is after (i thought it was to sort all the items within a module in a stable order - not sure the reason why you'd want this, but maybe to get better diffs?) because i'm not sure how this helps

Tony "Abolish ICE" Arcieri

Replying to

and

We're trying to run a code generator within a GitHub Action, and if the output diverges from what's checked in, automatically open a pull request. Unfortunately the generated code is nondeterministic so it's opening spurious PRs.

Replying to

Do you know why it's non-deterministic? Parallelism?

7:50 PM · Apr 5, 2021Twitter Web App

Tony "Abolish ICE" Arcieri

Replying to

My best guess is the code generator (which I don't directly control) uses HashMaps which are randomly seeded so as to avoid hashDoS. If it's simple as that, switching to BTreeMap should fix it, but I wasn't actually clear that was the source of the problem.