vim-patch:8.2.3725: cannot use a lambda for 'completefunc' and 'omnifunc'

Problem:    Cannot use a lambda for 'completefunc' and 'omnifunc'.
Solution:   Implement lambda support. (Yegappan Lakshmanan, closes vim/vim#9257)
https://github.com/vim/vim/commit/8658c759f05b317707d56e3b65a5ef63930c7498

Comment out Vim9 script in tests.

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index e6b038a335..d07cfe0bd9 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -1393,6 +1393,24 @@ func_call_skip_call:
   return r;
 }
 
+/// call the 'callback' function and return the result as a number.
+/// Returns -1 when calling the function fails.  Uses argv[0] to argv[argc - 1]
+/// for the function arguments. argv[argc] should have type VAR_UNKNOWN.
+///
+/// @param argcount  number of "argvars"
+/// @param argvars   vars for arguments, must have "argcount" PLUS ONE elements!
+varnumber_T callback_call_retnr(Callback *callback, int argcount, typval_T *argvars)
+{
+  typval_T rettv;
+  if (!callback_call(callback, argcount, argvars, &rettv)) {
+    return -1;
+  }
+
+  varnumber_T retval = tv_get_number_chk(&rettv, NULL);
+  tv_clear(&rettv);
+  return retval;
+}
+
 /// Give an error message for the result of a function.
 /// Nothing if "error" is FCERR_NONE.
 static void user_func_error(int error, const char_u *name)