Safety checks for ghc-mod.

syntax_checkers/haskell/ghc-mod.vim

@@ -15,8 +15,18 @@ if exists('g:loaded_syntastic_haskell_ghc_mod_checker')
 endif
 let g:loaded_syntastic_haskell_ghc_mod_checker = 1
 
+let s:ghc_mod_new = -1
+
+function! SyntaxCheckers_haskell_ghc_mod_IsAvailable() dict
+    " We need either a Vim version that can handle NULs in system() output,
+    " or a ghc-mod version that has the --boundary option.
+    let s:ghc_mod_new = executable(self.getExec()) ? s:GhcModNew(self.getExec()) : -1
+    return (s:ghc_mod_new >= 0) && (v:version >= 704 || s:ghc_mod_new)
+endfunction
+
 function! SyntaxCheckers_haskell_ghc_mod_GetLocList() dict
-    let makeprg = self.makeprgBuild({ 'exe': self.getExec() . ' check' })
+    let makeprg = self.makeprgBuild({
+        \ 'exe': self.getExec() . ' check' . (s:ghc_mod_new ? ' --boundary=""' : '') })
 
     let errorformat =
         \ '%-G%\s%#,' .
@@ -34,6 +44,17 @@ function! SyntaxCheckers_haskell_ghc_mod_GetLocList() dict
         \ 'postprocess': ['compressWhitespace'] })
 endfunction
 
+function! s:GhcModNew(exe)
+    try
+        let ghc_mod_version = filter(split(system(a:exe), '\n'), 'v:val =~# ''\m^ghc-mod version''')[0]
+        let ret = syntastic#util#versionIsAtLeast(syntastic#util#parseVersion(ghc_mod_version), [2, 1, 2])
+    catch /^Vim\%((\a\+)\)\=:E684/
+        call syntastic#util#error("checker haskell/ghc_mod: can't parse version string (abnormal termination?)")
+        let ret = -1
+    endtry
+    return ret
+endfunction
+
 call g:SyntasticRegistry.CreateAndRegisterChecker({
     \ 'filetype': 'haskell',
     \ 'name': 'ghc_mod',