patch 9.1.1541: Vim9: error when last enum value ends with a comma

Problem:  Vim9: error when last enum value ends with a comma
Solution: Allow trailing commas in enum values (Yegappan Lakshmanan).

closes: #17744

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_vim9_enum.vim

@@ -838,6 +838,25 @@ def Test_enum_values()
   END
   v9.CheckSourceSuccess(lines)
 
+  lines =<< trim END
+    vim9script
+    enum Car
+      Honda,
+      Ford,
+    endenum
+    assert_equal([Car.Honda, Car.Ford], Car.values)
+  END
+  v9.CheckSourceSuccess(lines)
+
+  lines =<< trim END
+    vim9script
+    enum Car
+      Honda, Ford,
+    endenum
+    assert_equal([Car.Honda, Car.Ford], Car.values)
+  END
+  v9.CheckSourceSuccess(lines)
+
   # empty enum
   lines =<< trim END
     vim9script
@@ -863,7 +882,7 @@ def Test_enum_values()
       Red,
       Blue
       static def GetValues(): list<A>
-	return values
+        return values
       enddef
     endenum
     assert_equal([A.Red, A.Blue], A.GetValues())
@@ -1050,6 +1069,34 @@ def Test_enum_refcount()
     assert_equal(4, test_refcount(Star.Orion))
   END
   v9.CheckSourceSuccess(lines)
+
+  lines =<< trim END
+    vim9script
+    enum Star
+      Gemini,
+      Orion,
+    endenum
+
+    assert_equal(3, test_refcount(Star))
+    assert_equal(2, test_refcount(Star.Gemini))
+    assert_equal(2, test_refcount(Star.Orion))
+
+    var x = [Star.Gemini]
+    assert_equal(3, test_refcount(Star))
+    assert_equal(3, test_refcount(Star.Gemini))
+
+    def Fn()
+      var y = [Star.Gemini, Star.Orion]
+      assert_equal(6, test_refcount(Star))
+      assert_equal(4, test_refcount(Star.Gemini))
+    enddef
+    Fn()
+    # The instruction in the compiled function adds an additional reference
+    # to the enum.
+    assert_equal(6, test_refcount(Star))
+    assert_equal(3, test_refcount(Star.Gemini))
+  END
+  v9.CheckSourceSuccess(lines)
 enddef
 
 " Test for defining an enum with additional object variables and methods

src/version.c

@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1541,
 /**/
     1540,
 /**/

src/vim9class.c

@@ -1855,6 +1855,7 @@ ex_class(exarg_T *eap)
     int		is_class = eap->cmdidx == CMD_class;
     int		is_abstract = eap->cmdidx == CMD_abstract;
     int		is_enum = eap->cmdidx == CMD_enum;
+    int		added_enum_values = FALSE;
     int		is_interface;
     long	start_lnum = SOURCING_LNUM;
     char_u	*arg = eap->arg;
@@ -2174,9 +2175,12 @@ early_ret:
 		break;
 
 	    if (enum_end)
+	    {
 		// Add the enum "values" class variable.
 		enum_add_values_member(cl, &classmembers, num_enum_values,
 							&type_list);
+		added_enum_values = TRUE;
+	    }
 	    continue;
 	}
 
@@ -2496,9 +2500,10 @@ early_ret:
 
     vim_free(theline);
 
-    if (success && is_enum && num_enum_values == 0)
+    if (success && is_enum && (num_enum_values == 0 || !added_enum_values))
 	// Empty enum statement. Add an empty "values" class variable
-	success = enum_add_values_member(cl, &classmembers, 0, &type_list);
+	success = enum_add_values_member(cl, &classmembers, num_enum_values,
+								&type_list);
 
     /*
      * Check a few things