refactor out some duplication of /dev/null logic

autoload/syntastic/util.vim

@@ -0,0 +1,18 @@
+if exists("g:loaded_syntastic_util_autoload")
+    finish
+endif
+let g:loaded_syntastic_util_autoload = 1
+
+let s:save_cpo = &cpo
+set cpo&vim
+
+function! syntastic#util#DevNull()
+    if has('win32')
+        return 'NUL'
+    endif
+    return '/dev/null'
+endfunction
+
+let &cpo = s:save_cpo
+unlet s:save_cpo
+" vim: set et sts=4 sw=4:

syntax_checkers/less.vim

@@ -42,12 +42,8 @@ else
 end
 
 function! SyntaxCheckers_less_GetLocList()
-    let devnull = '/dev/null'
-    if has('win32')
-        let devnull = 'NUL'
-    endif
     let makeprg = s:check_file . ' ' . g:syntastic_less_options . ' ' .
-                \ shellescape(expand('%')) . ' ' . devnull
+                \ shellescape(expand('%')) . ' ' . syntastic#util#DevNull()
     let errorformat = '%m in %f:%l:%c'
 
     return SyntasticMake({ 'makeprg': makeprg,

syntax_checkers/rst.vim

@@ -24,12 +24,8 @@ if !executable("rst2pseudoxml.py")
 endif
 
 function! SyntaxCheckers_rst_GetLocList()
-    let devnull = '/dev/null'
-    if has('win32')
-        let devnull = 'NUL'
-    endif
     let makeprg = 'rst2pseudoxml.py --report=2 --exit-status=1 ' .
-      \ shellescape(expand('%')) . ' ' . devnull
+      \ shellescape(expand('%')) . ' ' . syntastic#util#DevNull()
 
     let errorformat = '%f:%l:\ (%tNFO/1)\ %m,
       \%f:%l:\ (%tARNING/2)\ %m,

syntax_checkers/typescript.vim

@@ -14,11 +14,7 @@ if !executable("tsc")
 endif
 
 function! SyntaxCheckers_typescript_GetLocList()
-    let devnull = '/dev/null'
-    if has('win32')
-        let devnull = 'NUL'
-    endif
-    let makeprg = 'tsc ' . shellescape(expand("%")) . ' --out ' . devnull
+    let makeprg = 'tsc ' . shellescape(expand("%")) . ' --out ' . syntastic#util#DevNull()
     let errorformat = '%f (%l\,%c): %m'
     return SyntasticMake({ 'makeprg': makeprg, 'errorformat': errorformat })
 endfunction