Use region contents in racer-describe if active

[dcluna]

(thing-at-point 'symbol) (here) doesn't always retrieve what we want - for instance, when describing a namespaced fn - so we may want to check it against the active region to work around this.

[coveralls]

Coverage decreased (-0.08%) to 65.205% when pulling 9634a1a319b439ee769714ef43e9f6531e82e3f2 on dcluna:racer-describe-use-region into 6e0d1b3ebd54497c0cc995a92f09328ff101cd33 on racer-rust:master.

[coveralls]

Coverage decreased (-0.08%) to 65.205% when pulling 9634a1a319b439ee769714ef43e9f6531e82e3f2 on dcluna:racer-describe-use-region into 6e0d1b3ebd54497c0cc995a92f09328ff101cd33 on racer-rust:master.

[coveralls]

Coverage decreased (-0.08%) to 65.205% when pulling 9634a1a319b439ee769714ef43e9f6531e82e3f2 on dcluna:racer-describe-use-region into 6e0d1b3ebd54497c0cc995a92f09328ff101cd33 on racer-rust:master.

[Wilfred]

Hi @dcluna , thanks for the PR! :)

Could you give a code example where this is useful? I don't see how this affects racer-describe, since as you say it's using thing-at-point. We may also want to file a bug on upstream racer to make it smarter.

[dcluna]

Hi @Wilfred, thanks for reviewing!

I was looking at a piece of code like the following:

::std::env::var("MY_ENV_VAR")

and just putting point at var and running racer-describe didn't open the documentation for var as I expected. racer-debug returned the following:

$ $HOME/.cargo/bin/racer complete-with-snippet 753 31 my-file.rs /tmp/racer3881nsF

This command terminated with exit code 0.

stdout:

PREFIX 24647,24650,var
END

No output on stderr.

The temporary file will have been deleted. You should be
able to reproduce the same output from racer with the
following command:

$ CARGO_HOME=$HOME/.cargo RUST_SRC_PATH=$HOME/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src $HOME/.cargo/bin/racer complete-with-snippet 753 31 my-file.rs

The upstream racer command has a complete option that allows you to pass a fully-namespaced string for autocompletion, and that's what I'm using in this PR. It solved my problem, but as you say, maybe I should focus on fixing the upstream complete-with-snippet. I must admit I am not familiar with it - particularly, the numbers after PREFIX seem like internal pointers to crates to me, but I could use some guidance with it.

Anyway, have I made myself clear? Do you think this is mergeable (after adding some tests, ofc), or do you think this is a racer bug in the complete-with-snippet?

[Wilfred]

Thanks for the example. Based on it, I've written the following program, but I can't reproduce the issue:

fn main() {
    let v = ::std::env::var("MY_ENV_VAR");
}

I'm able to jump to definition and run racer-describe on var. What version of racer are you using?

[dcluna]

racer 2.0.9. There are some rustc errors in the crate I'm writing this code, so maybe that has something to do with it? What surprises me is that racer-call with complete does work. If this is expected behavior, I can change this PR to use the complete option if complete-with-snippet fails for whatever reason. WDYT?

[Wilfred]

Interesting that complete works. Could you share the file you're working on?

[dcluna]

https://github.com/rust-lang-nursery/rustup.rs/blob/9e1f621b80f9c0f80c295028be165c327b756a43/tests/cli-rustup.rs#L752

[Wilfred]

I can't see any references to ::std::env::var in that file, and ::std::env::current_dir seems to work as expected. How can I reproduce the issue?

[dcluna]

I added the following line (after line 752):

assert!(::std::env::var("RUST_SRC_PATH") == Ok(_));

It seems like this is mostly related to my own environment than any bug in racer or this plugin, so I'll close this and re-open if I manage to reproduce it reliably. Thanks for your patience on this!