vim-patch:9.0.0419: the :defer command does not check the function arguments

Problem:    The :defer command does not check the function argument count and
            types.
Solution:   Check the function arguments when adding a deferred function.

https://github.com/vim/vim/commit/169003289fb4b2ad18fd7f5807e0d05efff0be85

Cherry-pick check_internal_func() from Vim, but use EvalFuncDef pointer
as first argument.

Co-authored-by: Bram Moolenaar <Bram@vim.org>

1 files changed, 27 insertions, 4 deletions

diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 32f9f9182c..65918ba2bf 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -72,7 +72,7 @@ static funccall_T *current_funccal = NULL;
 // item in it is still being used.
 static funccall_T *previous_funccal = NULL;
 
-static const char *e_unknownfunc = N_("E117: Unknown function: %s");
+static const char *e_unknown_function_str = N_("E117: Unknown function: %s");
 static const char *e_funcexts = N_("E122: Function %s already exists, add ! to replace it");
 static const char *e_funcdict = N_("E717: Dictionary entry already exists");
 static const char *e_funcref = N_("E718: Funcref required");
@@ -1523,14 +1523,14 @@ varnumber_T callback_call_retnr(Callback *callback, int argcount, typval_T *argv
 /// 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 *name, funcexe_T *funcexe)
-  FUNC_ATTR_NONNULL_ALL
+  FUNC_ATTR_NONNULL_ARG(2)
 {
   switch (error) {
   case FCERR_UNKNOWN:
     if (funcexe->fe_found_var) {
       semsg(_(e_not_callable_type_str), name);
     } else {
-      emsg_funcname(e_unknownfunc, name);
+      emsg_funcname(e_unknown_function_str, name);
     }
     break;
   case FCERR_NOTMETHOD:
@@ -1543,7 +1543,7 @@ static void user_func_error(int error, const char *name, funcexe_T *funcexe)
     emsg_funcname(_(e_toomanyarg), name);
     break;
   case FCERR_TOOFEW:
-    emsg_funcname(N_("E119: Not enough arguments for function: %s"), name);
+    emsg_funcname(_(e_toofewarg), name);
     break;
   case FCERR_SCRIPT:
     emsg_funcname(N_("E120: Using <SID> not in a script context: %s"), name);
@@ -3172,6 +3172,29 @@ static int ex_defer_inner(char *name, char **arg, const partial_T *const partial
   }
   int r = get_func_arguments(arg, evalarg, false, argvars + partial_argc, &argcount);
   argcount += partial_argc;
+
+  if (r == OK) {
+    if (builtin_function(name, -1)) {
+      const EvalFuncDef *const fdef = find_internal_func(name);
+      if (fdef == NULL) {
+        emsg_funcname(e_unknown_function_str, name);
+        r = FAIL;
+      } else if (check_internal_func(fdef, argcount) == -1) {
+        r = FAIL;
+      }
+    } else {
+      ufunc_T *ufunc = find_func(name);
+      // we tolerate an unknown function here, it might be defined later
+      if (ufunc != NULL) {
+        int error = check_user_func_argcount(ufunc, argcount);
+        if (error != FCERR_UNKNOWN) {
+          user_func_error(error, name, NULL);
+          r = FAIL;
+        }
+      }
+    }
+  }
+
   if (r == FAIL) {
     while (--argcount >= 0) {
       tv_clear(&argvars[argcount]);