require cargo version >= 0.16.0, fix style nits

Author: jlevesy

syntax_checkers/rust/cargo.vim

@@ -8,15 +8,18 @@
 if exists("g:loaded_syntastic_rust_cargo_checker")
     finish
 endif
+
 let g:loaded_syntastic_rust_cargo_checker = 1
 
+" Force syntastic to call cargo without a specific file name
 let g:syntastic_rust_cargo_fname = ""
 
 let s:save_cpo = &cpo
 set cpo&vim
 
 function! SyntaxCheckers_rust_cargo_IsAvailable() dict
-  return executable(self.getExec())
+  return executable(self.getExec()) &&
+    \ syntastic#util#versionIsAtLeast(self.getVersion(), [0, 16, 0])
 endfunction
 
 function! SyntaxCheckers_rust_cargo_GetLocList() dict
@@ -26,8 +29,7 @@ function! SyntaxCheckers_rust_cargo_GetLocList() dict
     let errorformat  =
         \ '%-G,' .
         \ '%-Gerror: aborting %.%#,' .
-        \ '%-Gerror: Could not compile %.%#,' .
-        \ '%-Gwarning: the option `Z` is unstable %.%#,'
+        \ '%-Gerror: Could not compile %.%#,'
 
     " Meaningful lines (errors, notes, warnings, contextual information)
     let errorformat .=