Syntastic compatibility nonfunctional when using nightly

[ExpHP]

There are several factors possibly at play here (rustc, rustup, rust.vim, syntastic); I chose to report on rust.vim as it is the middleman.

Steps to reproduce

1. Install both rust.vim and syntastic. For full disclosure: from a clean vim, I installed pathogen, cloned the plugin repos into .vim/patho, and used this .vimrc

   execute pathogen#infect('patho/{}')
   set statusline+=%#warningmsg#
   set statusline+=%{SyntasticStatuslineFlag()}
   set statusline+=%*
   

2. Make two new crates, one on nightly

   cargo new --bin test-nightly && (cd test-nightly && rustup override set nightly)
   cargo new --bin test-stable
   

3. For each one, do the following:

    $ cd <test dir name>
    $ vim src/main.rs

Verify that all lights are green:

    :SyntasticInfo
    Syntastic version: 3.7.0-180 (Vim 704, Linux)
    Info for filetype: rust
    Global mode: active
    Filetype rust is active
    The current file will be checked automatically
    Available checker: rustc
    Currently enabled checker: rustc

Insert a deliberate error (unpared parenthesis) and write the file.

    O(<Esc>:w<Enter>

What occurs

In test-stable: After the file is written, syntastic will flag errors in the gutter and statusline.
In test-nightly: After the file is written, nothing happens.

Versions installed

uname -a: Linux lampam-ThinkPad-T430 4.4.0-31-generic #50-Ubuntu SMP Wed Jul 13 00:07:12 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
rustup: rustup 0.5.0 (4be1012 2016-07-30)
rust.vim: (git hash) 7304385
syntastic: (git hash) aa2a09110956e46652a9cb247ec24a57797066fd
vim: VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Jun 16 2016 10:50:38)

Versions of rustc tested: (OK means syntastic highlights the error)
OK: rustc 1.10.0 (cfcb716cf 2016-07-03)
OK: rustc 1.11.0-beta.3 (052e32bd9 2016-08-08)
FAIL: rustc 1.12.0-nightly (0ef24eed2 2016-08-10)
FAIL: rustc 1.12.0-nightly (8787a1233 2016-08-11)

[ExpHP]

Notice: It also works fine for beta. Only nightly is affected.

[ExpHP]

After further testing I believe the cause is due to the new error format.

This is because, when using override set beta, the following exhibits the issue:

RUST_NEW_ERROR_FORMAT=true vim src/main.rs

while no issue occurs when vim is invoked without the env var.

Edit: Related to #88

[iamsebastian]

A hint for people, looking for syntax-checking their work on nightly:

While it's not possible to use syntastic with nightly atm., you can check your whole crate / project with snippets like these:

Just parsing:

❯ find ./ | egrep "\.rs$" | xargs -L1 rustc -Z parse-only
#or with silversearcher
❯ ag -g \.rs\$ | xargs -L1 rustc -Z parse-only 

Run all passes without translation:

❯ find ./ | egrep "\.rs$" | xargs -L1 rustc -Z no-trans
#or with silversearcher
❯ ag -g \.rs\$ | xargs -L1 rustc -Z no-trans

[leeola]

For those wanting to solve this problem with Neomake, the following Maker will solve this issue. A bit verbose, i'm including my docstrings on it.

" create our actual neomake maker for cargo. Note that neomake ships with a
" default maker, but it is not using the new error format which resides in
" nightly.
"
" I'm using an explicit 'cargo' exe name incase i want to change the maker
" name without affecting the binary. `append_file` is used because neomake
" will automatically append the file path to the end of the full command,
" which causes cargo to fail. Finally, the errorformat was pulled from
" a rust.vim PR[1] attempting to fix the problem that causes me to add
" this whole neomake maker. Thanks to them!!
"
" [1]: https://github.com/rust-lang/rust.vim/pull/99#issuecomment-244954595
let g:neomake_rust_cargo_maker = {
    \ 'exe': 'cargo',
    \ 'args': ['build'],
    \ 'append_file': 0,
    \ 'errorformat': '%Eerror%m,%Z\ %#-->\ %f:%l:%c',
  \ }
" Replace the default makers list with our new maker, ensuring our cargo maker
" and not the default maker is what is run when we save.
let g:neomake_rust_enabled_makers = ['cargo']
" Automatically run this maker when we save .rs files.
autocmd! BufWritePost *.rs Neomake cargo

This won't help you if you're looking for Syntastic support, but i quite like Neomake's take on this. Also useful, let g:rustfmt_fail_silently=1 if you want rust.vim not to print rustfmt errors that neomake likely is already displaying.

Even if you prefer Syntastic, this may be a nice temporary measure for some of you :)

[k0pernicus]

Thank you for this solution, but when I'm using this code and an error using Animals::Rat insteads of Animal::Cat, I only have this error: Neomake: cargo completed with exit code 101.
Do I need to update my neovim configuration code?

Thanks!

[ExpHP]

Hm, looks like I never made a link between this issue and PR #99. (now I have!)

I have been using that branch for a while now and believe it solves the brunt of the issue, so I plan to close this once it goes through. (for any remaining problems I imagine it might be better to raise new issues)