Merge pull request #2289 from bhcleek/lsp/functions-preview

lsp: show function signature with return types in preview window

autoload/go/lsp.vim

@@ -458,6 +458,9 @@ function! s:completionHandler(next, msg) abort dict
     let l:match = {'abbr': l:item.label, 'word': l:item.textEdit.newText, 'info': '', 'kind': go#lsp#completionitemkind#Vim(l:item.kind)}
     if has_key(l:item, 'detail')
         let l:match.info = l:item.detail
+        if go#lsp#completionitemkind#IsFunction(l:item.kind) || go#lsp#completionitemkind#IsMethod(l:item.kind)
+          let l:match.info = printf('func %s %s', l:item.label, l:item.detail)
+        endif
     endif
 
     if has_key(l:item, 'documentation')

autoload/go/lsp/completionitemkind.vim

@@ -28,7 +28,7 @@ let s:Event = 23
 let s:Operator = 24
 let s:TypeParameter = 25
 
-function! go#lsp#completionitemkind#Vim(kind)
+function! go#lsp#completionitemkind#Vim(kind) abort
   if a:kind == s:Method || a:kind == s:Function || a:kind == s:Constructor
     return 'f'
   elseif a:kind == s:Variable || a:kind == s:Constant
@@ -40,6 +40,22 @@ function! go#lsp#completionitemkind#Vim(kind)
   endif
 endfunction
 
+function! go#lsp#completionitemkind#IsFunction(kind) abort
+  if a:kind == s:Function
+    return 1
+  endif
+
+  return 0
+endfunction
+
+function! go#lsp#completionitemkind#IsMethod(kind) abort
+  if a:kind == s:Method
+    return 1
+  endif
+
+  return 0
+endfunction
+
 " restore Vi compatibility settings
 let &cpo = s:cpo_save
 unlet s:cpo_save