fix(api): add missing nargs field to user command Lua callbacks #34210

Problem: nvim_create_user_command() Lua callbacks were missing the documented nargs field in the options table passed to the callback function.

Solution: Add nargs field derivation from command argument type flags in nlua_do_ucmd(), using the same logic as nvim_parse_cmd().

1 files changed, 20 insertions, 0 deletions

diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index fc11d2b966..2f5c7566f4 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -2206,6 +2206,26 @@ int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
   }
   lua_setfield(lstate, -2, "count");
 
+  char nargs[2];
+  if (cmd->uc_argt & EX_EXTRA) {
+    if (cmd->uc_argt & EX_NOSPC) {
+      if (cmd->uc_argt & EX_NEEDARG) {
+        nargs[0] = '1';
+      } else {
+        nargs[0] = '?';
+      }
+    } else if (cmd->uc_argt & EX_NEEDARG) {
+      nargs[0] = '+';
+    } else {
+      nargs[0] = '*';
+    }
+  } else {
+    nargs[0] = '0';
+  }
+  nargs[1] = NUL;
+  lua_pushstring(lstate, nargs);
+  lua_setfield(lstate, -2, "nargs");
+
   // The size of this buffer is chosen empirically to be large enough to hold
   // every possible modifier (with room to spare). If the list of possible
   // modifiers grows this may need to be updated.