Add syntastic_rustc_config_file handling

[brookst]

Add args from g:syntastic_rustc_config_file to rustc command.
Had to borrow syntastic#c#ReadConfig code to parse the -L flag.

Could this function be made more general to allow reuse?

[lcd047]

Had to borrow syntastic#c#ReadConfig code to parse the -L flag.

Oh please, you can do much better than that. Like, add an option to syntastic#c#ReadConfig() to handle -L, or simply add that to syntastic#c#ReadConfig() (off hand, I think all compilers have that option).

Still, can you pleaes give an example why is all this needed in the first place?

[brookst]

I'm using this to add an external library to the checker. It doesn't make sense to do this globally so I thought a project-local config file would be the way to do this: This is how I set up C++ projects. Is there a better way to provide library paths on a project local basis?

It was my intention to reuse the ReadConfig function but I didn't want to start changing it without some comments on what would be best to do. I don't know if any other checkers would use library paths like this, I guess it's just a rust quirk that libraries are linked with -L instead of -I.

[lcd047]

This is better, but it still seems to be way overkill. Config files are useful for long, complicated lists of options. As far as I can tell, in your case a simple autocmd would be enough:

autocmd /some/path/*.rs let g:syntastic_rust_rustc_args='-L /some/other/path'

[brookst]

Hmm, to me it just seems more intuitive to put these options in a file with the projects they relate to. Having a stack of autocmds in my vimrc doesn't seem very appealing.

Unless you mean in a local vimrc but I thought they were frowned upon.

Would it not make sense for rustc to read config files, given many other checkers do?

[lcd047]

Using autocmd is Vim's way of doing things. It's still cleaner than adding an option that is useful for a single checker. shrug

[brookst]

OK, what if I don't touch the ReadConfig and just use args as:

-Lpath/to/lib

or

-L
path/to/lib

Then there's no extra option. (I re-read the wiki entry on config files)

[lcd047]

Like I said, for better or worse, using autocmd for that is the Vim way. One line in your vimrc, as opposed to many more lines in syntastic. shrug