vim-patch:8.1.1732: completion in cmdwin does not work for buffer-local commands

Problem:    Completion in cmdwin does not work for buffer-local commands.
Solution:   Use the right buffer. (closes vim/vim#4711)
https://github.com/vim/vim/commit/f03e328348f87e1fe8ce4aad2a6a4237b9f78ce3

1 files changed, 17 insertions, 7 deletions

diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 641edf4610..f18ebffa0a 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -5133,9 +5133,11 @@ static void uc_list(char_u *name, size_t name_len)
   ucmd_T      *cmd;
   int len;
   uint32_t a;
-  garray_T    *gap;
 
-  gap = &curbuf->b_ucmds;
+  // In cmdwin, the alternative buffer should be used.
+  garray_T *gap = (cmdwin_type != 0 && get_cmdline_type() == NUL)
+    ? &prevwin->w_buffer->b_ucmds
+    : &curbuf->b_ucmds;
   for (;; ) {
     for (i = 0; i < gap->ga_len; ++i) {
       cmd = USER_CMD_GA(gap, i);
@@ -5984,13 +5986,21 @@ char_u *get_user_cmd_addr_type(expand_T *xp, int idx)
 /*
  * Function given to ExpandGeneric() to obtain the list of user command names.
  */
-char_u *get_user_commands(expand_T *xp, int idx)
+char_u *get_user_commands(expand_T *xp FUNC_ATTR_UNUSED, int idx)
+  FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  if (idx < curbuf->b_ucmds.ga_len)
-    return USER_CMD_GA(&curbuf->b_ucmds, idx)->uc_name;
-  idx -= curbuf->b_ucmds.ga_len;
-  if (idx < ucmds.ga_len)
+  // In cmdwin, the alternative buffer should be used.
+  const buf_T *const buf = (cmdwin_type != 0 && get_cmdline_type() == NUL)
+    ? prevwin->w_buffer
+    : curbuf;
+
+  if (idx < buf->b_ucmds.ga_len) {
+    return USER_CMD_GA(&buf->b_ucmds, idx)->uc_name;
+  }
+  idx -= buf->b_ucmds.ga_len;
+  if (idx < ucmds.ga_len) {
     return USER_CMD(idx)->uc_name;
+  }
   return NULL;
 }