Single integrated UI for all rust tooling

[brson]

As discussed in this week's meeting, let's create a single command-line interface that encompasses all of the rust tooling, and presents a simple and consistent experience for all aspects of rust programming.

We currently have three tools, rustc, cargo and rustdoc, and we will likely soon bee writing a bunch of new build logic for #2237.

Go has a go command that is a one-stop shop for working on go projects. We should learn from this. I thought this description of their motivation rang a bell:

An explicit goal for Go from the beginning was to be able to build Go code using only the information found in the
source itself, not needing to write a makefile or one of the many modern replacements for makefiles. If Go needed
a configuration file to explain how to build your program, then Go would have failed.

[brson]

@pcwalton suggested we do something like git with git-foo subcommands and I agree. Furthermore, I suggest implementing it with dynamically loaded crates for each subcommand so that folks can use cargo to write and install new ones.

[graydon]

See also https://github.com/mozilla/rust/wiki/Meeting-weekly-2012-11-13

[Kimundi]

I implemented a first version (#5014). It just forwards arguments to rustc, rusti, rustdoc and rustpkg and adds a few convenient shortcuts.

[catamorphism]

FIXMEs from the code for the rust tool:

// FIXME Make commands run and test emit proper file endings on winds
// FIXME Make run only accept source that emits an executable

[kud1ing]

There is a rust tool now. Should this issue be closed in the tradition of opening follow-up issues for outstanding details?

[thestinger]

@kud1ing: closing, thanks

[emberian]

Reopening, since rust is removed (unmaintained).

[thestinger]

I don't think we should have more than one frontend to the same tool, so I think we need to decide between a single tool or more than one. It's too much of a pain to support both, and having rust as a thin wrapper around the other was not pretty.

[alexchandel]

pcwalton's pretty printer, similar to go fmt.

Go also has go build, go clean, go test, and go run, similar to cargo build, cargo clean, cargo test, and cargo run; though Cargo adds the new, bench, and update commands.

Conceivably, in addition to rust build, rust clean, rust test, rust run, rust new, rust bench, rust update, rust doc, rust fmt, there would also be a rust compile for rustc.

And should rusti ever return, then just rust could begin the interpreter. The same goes for rust-bindgen being adopted and rust bindgen. This seems like a cleaner solution than the jumble of executables that currently exist.

[brson]

No pressing need for this these days. Cargo handles most of what people use at the moment. I don't think this is happening any time soon.