package: improve import_path by using go list

autoload/go/guru.vim

@@ -16,8 +16,7 @@ function! s:guru_cmd(args) range abort
   let selected = a:args.selected
 
   let result = {}
-  let dirname = expand('%:p:h')
-  let pkg = go#package#ImportPath(dirname)
+  let pkg = go#package#ImportPath()
 
   " this is important, check it!
   if pkg == -1 && needs_scope

autoload/go/jobcontrol.vim

@@ -52,7 +52,7 @@ function! s:spawn(bang, desc, args) abort
         \ 'desc': a:desc,
         \ 'bang': a:bang,
         \ 'winnr': winnr(),
-        \ 'importpath': go#package#ImportPath(expand('%:p:h')),
+        \ 'importpath': go#package#ImportPath(),
         \ 'state': "RUNNING",
         \ 'stderr' : [],
         \ 'stdout' : [],

autoload/go/lint.vim

@@ -171,13 +171,13 @@ endfunction
 " the location list
 function! go#lint#Errcheck(...) abort
   if a:0 == 0
-    let goargs = go#package#ImportPath(expand('%:p:h'))
-    if goargs == -1
+    let import_path = go#package#ImportPath()
+    if import_path == -1
       echohl Error | echomsg "vim-go: package is not inside GOPATH src" | echohl None
       return
     endif
   else
-    let goargs = go#util#Shelljoin(a:000)
+    let import_path = go#util#Shelljoin(a:000)
   endif
 
   let bin_path = go#path#CheckBinPath(g:go_errcheck_bin)
@@ -188,7 +188,7 @@ function! go#lint#Errcheck(...) abort
   echon "vim-go: " | echohl Identifier | echon "errcheck analysing ..." | echohl None
   redraw
 
-  let command = bin_path . ' -abspath ' . goargs
+  let command = bin_path . ' -abspath ' . import_path
   let out = go#tool#ExecuteInDir(command)
 
   let l:listtype = "quickfix"
@@ -199,14 +199,14 @@ function! go#lint#Errcheck(...) abort
     call go#list#ParseFormat(l:listtype, errformat, split(out, "\n"), 'Errcheck')
 
     let errors = go#list#Get(l:listtype)
-
     if empty(errors)
       echohl Error | echomsg "GoErrCheck returned error" | echohl None
       echo out
       return
     endif
 
     if !empty(errors)
+      echohl Error | echomsg "GoErrCheck found errors" | echohl None
       call go#list#Populate(l:listtype, errors, 'Errcheck')
       call go#list#Window(l:listtype, len(errors))
       if !empty(errors)

autoload/go/package.vim

@@ -54,29 +54,25 @@ function! go#package#Paths() abort
   return dirs
 endfunction
 
-function! go#package#ImportPath(arg) abort
-  let path = fnamemodify(resolve(a:arg), ':p')
-  let dirs = go#package#Paths()
+" ImportPath returns the import path in the current directory it was executed
+function! go#package#ImportPath() abort
+  let out = go#tool#ExecuteInDir("go list")
+  if go#util#ShellError() != 0
+    return -1
+  endif
 
-  for dir in dirs
-    if len(dir) && matchstr(escape(path, '\/'), escape(dir, '\/')) == 0
-      let workspace = dir
-    endif
-  endfor
+  let import_path = split(out, '\n')[0]
 
-  if !exists('workspace')
+  " go list returns '_CURRENTDIRECTORY' if the directory is not inside GOPATH.
+  " Check it and retun an error if that is the case
+  if import_path[0] ==# '_'
     return -1
   endif
 
-  if go#util#IsWin()
-    let srcdir = substitute(workspace . '\src\', '//', '/', '')
-    return path[len(srcdir):]
-  else
-    let srcdir = substitute(workspace . '/src/', '//', '/', '')
-    return substitute(path, srcdir, '', '')
-  endif
+  return import_path
 endfunction
 
+
 function! go#package#FromPath(arg) abort
   let path = fnamemodify(resolve(a:arg), ':p')
   let dirs = go#package#Paths()