separate rust-format or rustfmt tool that does the pretty-printing

[dbp]

It would be really nice to have the pretty printer be good enough to use it as a code formatter, ala gofmt. It still has some issues (I've been working on it), but it is reasonably close to being usable in that way.

But, the commandline invocation is kind of unwieldy (and feels redundant). It seems like --pretty should just pretty print, and other stuff should be handled secondarily, ie with:

--pretty-expanded
--pretty-typed
--pretty-expanded-identified
--pretty-identified

Alternatively, perhaps it would make more sense to actually split it into a separate binary, called rustfmt (or, in longer-keyword land, rustformat).

Thoughts?

[brson]

I would prefer it to be a separate tool.

[graydon]

Yeah, this is going to move out to a separate tool a la gofmt along with something similar to gofix that has archived copies of old grammars and knows how to migrate code forward between language versions. I'll rename this bug.

[graydon]

Note: this is a relative bug of #2238

[graydon]

nominating for backwards-compatible milestone

[nikomatsakis]

if possible, I'd prefer to retain the option (perhaps with -Z) to print out the expanded+identified tree. The reason is that it is very common for me to take a rustc FOO BAR ZED command line and tack on --pretty expanded+identified so that I can know what all the node ids refer to.

[graydon]

Marking as a metabug and collecting in dependencies: #751 #850 #2951 #5181
Also note that https://github.com/dbp/rustfmt does contain a sketch. But the tool frontend is less the hard part. Getting the pp in good enough state to take over is the hard part.

[msullivan]

What's the status of this?

[emberian]

The pretty printer becomes more and more broken as time goes on. @MaikKlein was working on a separate rust format, even had a PR for it.

[MaikKlein]

@cmr I was using pretty printer for the formating. But I realized it was pretty broken. It often didn't even parse legit code. I wanted to do some work to improve the pretty printer but I had no time.