Attempt to detect CM files in SML/NJ checker

[jez]

When editing SML/NJ files inside projects that use Compilation Manager for build
management, Syntastic displays errors incorrectly because it makes no attempt to
look for these *.cm files.

This pull request lets the smlnj checker find the CM file and appropriately
configure the makeprg when these one of these files is present.

Let me know if this is a feature you'd like or not like to include in Syntastic.
I'm open to suggestions. I wrote a bit of documentation in the file itself; I'm
not sure if we'd need to update any documentation elsewhere if this were to be
merged.

[lcd047]

Actually, you can achieve the same thing without changes to the code. Something like this:

function! s:DetectCM(fname) abort
    let cm = syntastic#util#findGlobInParent('*.cm', fnamemodify(a:fname, ':p:h'))
    if cm !=# ''
        let buf = bufnr(fnameescape(a:fname))
        call setbufvar(buf, 'syntastic_sml_smlnj_args', '-m ' . syntastic#util#shescape(cm))
        call setbufvar(buf, 'syntastic_sml_smlnj_fname', '')
    endif
endfunction

autocmd FileType sml     call s:DetectCM(expand('<amatch>', 1))

Or perhaps put the relevant piece of code in a ftplugin. Either way, it's the kind of manipulation that doesn't make sense for everybody, and thus it's better kept out of syntastic. Sorry, but no.

[jez]

Thanks for the tip! I had no idea that findGlobInParent was already a function; that certainly makes it simpler.

For those who end up finding this issue from a search: I've made this into a plugin (with a few other goodies for SML in general): jez/vim-better-sml.

@lcd047 Out of curiosity, is the existence of syntastic#util documented anywhere? I checked over the wiki documentation on writing a checker but didn't see any mention there.

Thanks again for the snappy response!

[lcd047]

I've made this into a plugin

I sent you a PR.

If you add initialisation to your plugin you'll also need to make sure syntastic is loaded before the rest of the code gets to run. This is not a problem for a ftplugin though, at least not until somebody tries to get smart and thinks to use the new :packadd command to delay loading syntastic until it's actually needed.

Out of curiosity, is the existence of syntastic#util documented anywhere?

It depends on what you mean by that. :h autoload will explain the basics. Beyond that, well, nobody took up the task of documenting the util functions, and the API is still subject to change; some people still seem to have high hopes that syntastic will be able to do async checks some day.

[jez]

If you add initialisation to your plugin you'll also need to make sure syntastic is loaded before the rest of the code gets to run.

I thought about that; I'll probably deal with it if it ever becomes an issue.

It depends on what you mean by that.

I was more referring to which functions were available in util. If the API is still subject to change, it's understandable that it's undocumented. I guess I'll just keep this in mind if my plugin breaks after an update 😛