fix ocaml#553

neovim specific fixes:
- feature identification is slightly different from vim
- state leaking is not the same as in vim

Maybe this makes the type histoy works with vim 7.4 before patch 424?!

Author: let-def

vim/merlin/autoload/merlin.vim

@@ -207,7 +207,7 @@ function! s:ShowTypeEnclosing(type)
 
   let g:merlin_latest_type = a:type['type']
 
-  if g:merlin_type_history_height <= 0 || v:version <= 703 || !has("patch-7.4.424")
+  if g:merlin_type_history_height <= 0 || (!has("nvim") && (v:version <= 703 || !has("patch-7.4.424")))
     echo a:type['type'] . a:type['tail_info']
     return
   endif

vim/merlin/autoload/merlin_type.vim

@@ -62,11 +62,20 @@ function! s:RecordType(type)
 
   " vimscript can't append to a buffer without a refresh (?!)
   MerlinPy << EOF
+
+# Vim cursor is a global state that will leak.
+# Nvim will complain the cursor is outside of buffer (using cursor from
+# current buffer in the type buffer).
+# So put it to origin and restore it later.
+cw = vim.current.window
+cursor = cw.cursor
+cw.cursor = (1,0)
+
 idx = int(vim.eval("g:merlin_type_history"))
 typ = vim.eval("a:type")
 buf = vim.buffers[idx]
-# nous souhaitons informer notre aimable clientèle qu'un combat d'infirme se déroule
-# à la ligne suivante
+# nous souhaitons informer notre aimable clientèle qu'un combat d'infirme se
+# déroule à la ligne suivante
 typ = list(map(lambda x: " " if (x == "") else x, typ))
 l = len(buf)
 if l > 1:
@@ -79,7 +88,7 @@ else:
 
 # Note that this leaves a blank line at the beginning of the buffer, but
 # it is apparently the desired behavior.
-
+cw.cursor = cursor
 EOF
 endfunction