Massive update :)

autoload/go/complete.vim

@@ -28,43 +28,75 @@ if len(s:goarch) == 0
   endif
 endif
 
+function! go#complete#PackageMembers(package, member)
+  silent! let content = system('godoc ' . a:package)
+  if v:shell_error || !len(content)
+    return []
+  endif
+  let lines = filter(split(content, "\n"),"v:val !~ '^\\s\\+$'")
+  try
+    let mx1 = '^\s\+\(\S+\)\s\+=\s\+.*'
+    let mx2 = '^\%(const\|var\|type\|func\) \([A-Z][^ (]\+\).*'
+    let candidates =
+    \   map(filter(copy(lines), 'v:val =~ mx1'), 'substitute(v:val, mx1, "\\1", "")')
+    \ + map(filter(copy(lines), 'v:val =~ mx2'), 'substitute(v:val, mx2, "\\1", "")')
+    return filter(candidates, '!stridx(v:val, a:member)')
+  catch
+    return []
+  endtry
+endfunction
+
 function! go#complete#Package(ArgLead, CmdLine, CursorPos)
   let dirs = []
 
+  let words = split(a:CmdLine, '\s\+', 1)
+  if len(words) > 2
+    " Complete package members
+    return go#complete#PackageMembers(words[1], words[2])
+  endif
+
   if executable('go')
-      let goroot = substitute(system('go env GOROOT'), '\n', '', 'g')
-      if v:shell_error
-          echo '\'go env GOROOT\' failed'
-      endif
+    let goroot = substitute(system('go env GOROOT'), '\n', '', 'g')
+    if v:shell_error
+      echomsg '\'go env GOROOT\' failed'
+    endif
   else
-      let goroot = $GOROOT
+    let goroot = $GOROOT
   endif
 
   if len(goroot) != 0 && isdirectory(goroot)
-    let dirs += [ goroot ]
+    let dirs += [goroot]
   endif
 
-  let workspaces = split($GOPATH, ':')
+  let pathsep = ':'
+  if s:goos == 'windows'
+    let pathsep = ';'
+  endif
+  let workspaces = split($GOPATH, pathsep)
   if workspaces != []
-      let dirs += workspaces
+    let dirs += workspaces
   endif
 
   if len(dirs) == 0
-      " should not happen
-      return []
+    " should not happen
+    return []
   endif
 
   let ret = {}
   for dir in dirs
-    let root = expand(dir . '/pkg/' . s:goos . '_' . s:goarch)
-    for i in split(globpath(root, a:ArgLead.'*'), "\n")
-      if isdirectory(i)
-        let i .= '/'
-      elseif i !~ '\.a$'
-        continue
-      endif
-      let i = substitute(substitute(i[len(root)+1:], '[\\]', '/', 'g'), '\.a$', '', 'g')
-      let ret[i] = i
+    " this may expand to multiple lines
+    let root = split(expand(dir . '/pkg/' . s:goos . '_' . s:goarch), "\n")
+    call add(root, expand(dir . '/src'))
+    for r in root
+      for i in split(globpath(r, a:ArgLead.'*'), "\n")
+        if isdirectory(i)
+          let i .= '/'
+        elseif i !~ '\.a$'
+          continue
+        endif
+        let i = substitute(substitute(i[len(r)+1:], '[\\]', '/', 'g'), '\.a$', '', 'g')
+        let ret[i] = i
+      endfor
     endfor
   endfor
   return sort(keys(ret))