Turn `--reorganize-definitions` on by default

[rinon]

I think reorg is now stable enough to be turned on by default. However, I'd like rust-lang/rust#66464 to get fixed before we do. Large codebases (e.g. python2 & nginx) trigger this bug after doing reorg.

[rinon]

We can do this after #217 lands.

[jrmuizel]

#217 has landed. Can this happen?

[kkysen]

rust-lang/rust#66464 has also been fixed by now. @rinon, is this still something we should enable?

[rinon]

Unfortunately we can't support reorganize-definitions until we have some sort of refactoring support again. This feature uses a global refactoring pass after transpiling to gather and organize declarations and definitions across modules. We really need a substitute for the refactoring engine (or resurrecting it as is with a newer nightly), as reorg was a pretty critical feature IMO.

[kkysen]

Is --reorganize-definitions using c2rust-refactor directly? It's still an option in c2rust transpile --help. Or is it just not very useful without the refactor afterwards?

Also, maybe once MIR is stabilized, we could update the refactoring engine to use that and just leave it, not having to worry about nightly updates anymore:

• https://rust-lang.zulipchat.com/#narrow/stream/320896-project-stable-mir
• Add WIP stable MIR crate rust-lang/rust#97385

[rinon]

We should remove it from the options... at least for now. It requires c2rust-refactor and will fail to work properly without it.

I'm not sure MIR helps us, because ultimately we need to transform text, rather than an underlying IR, in order to refactor things.

[kkysen]

Ok, I can remove the option then.

For the refactoring in general, I don't know much about it, but rust-analyzer and Intellij Rust have improved dramatically in the last few years and may be able to do a lot of the simpler refactorings we want, though I'm not sure on the details there. Even clippy; I wonder what it says about redundant casts, for example.