patch 9.1.1531: confusing error with nested legacy function

Problem:  confusing error with nested legacy function
          (lacygoill)
Solution: clarify error message E1117 with :def or :func (Hirohito Higashi)

fixes: #17697
closes: #17702

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/errors.h

@@ -2885,8 +2885,8 @@ EXTERN char e_assert_fails_fourth_argument[]
 	INIT(= N_("E1115: \"assert_fails()\" fourth argument must be a number"));
 EXTERN char e_assert_fails_fifth_argument[]
 	INIT(= N_("E1116: \"assert_fails()\" fifth argument must be a string"));
-EXTERN char e_cannot_use_bang_with_nested_def[]
-	INIT(= N_("E1117: Cannot use ! with nested :def"));
+EXTERN char e_cannot_use_bang_with_nested_def_str[]
+	INIT(= N_("E1117: Cannot use ! with nested %s"));
 EXTERN char e_cannot_change_locked_list[]
 	INIT(= N_("E1118: Cannot change locked list"));
 EXTERN char e_cannot_change_locked_list_item[]

src/testdir/test_vim9_func.vim

@@ -1001,7 +1001,18 @@ def Test_nested_function()
         enddef
       enddef
   END
-  v9.CheckDefFailure(lines, 'E1117:')
+  v9.CheckDefFailure(lines, 'E1117: Cannot use ! with nested :def')
+
+  lines =<< trim END
+      def Outer()
+        function Inner()
+          " comment
+        endfunc
+        function! Inner()
+        endfunc
+      enddef
+  END
+  v9.CheckDefFailure(lines, 'E1117: Cannot use ! with nested :function')
 
   lines =<< trim END
       vim9script

src/version.c

@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1531,
 /**/
     1530,
 /**/

src/vim9compile.c

@@ -1035,7 +1035,8 @@ compile_nested_function(exarg_T *eap, cctx_T *cctx, garray_T *lines_to_free)
 
     if (eap->forceit)
     {
-	emsg(_(e_cannot_use_bang_with_nested_def));
+	semsg(_(e_cannot_use_bang_with_nested_def_str),
+		eap->cmdidx == CMD_def ? ":def" : ":function");
 	return NULL;
     }