entc/gen: support de/incrementing values on upsert

Fixed https://github.com/ent/ent/issues/1952.

entc/integration/ent/task_create.go

@@ -229,6 +229,12 @@ func (u *TaskUpsert) UpdatePriority() *TaskUpsert {
 	return u
 }
 
+// AddPriority adds v to the "priority" field.
+func (u *TaskUpsert) AddPriority(v schema.Priority) *TaskUpsert {
+	u.Add(task.FieldPriority, v)
+	return u
+}
+
 // UpdateNewValues updates the fields using the new values that were set on create.
 // Using this option is equivalent to using:
 //
@@ -278,6 +284,13 @@ func (u *TaskUpsertOne) SetPriority(v schema.Priority) *TaskUpsertOne {
 	})
 }
 
+// AddPriority adds v to the "priority" field.
+func (u *TaskUpsertOne) AddPriority(v schema.Priority) *TaskUpsertOne {
+	return u.Update(func(s *TaskUpsert) {
+		s.AddPriority(v)
+	})
+}
+
 // UpdatePriority sets the "priority" field to the value that was provided on create.
 func (u *TaskUpsertOne) UpdatePriority() *TaskUpsertOne {
 	return u.Update(func(s *TaskUpsert) {
@@ -496,6 +509,13 @@ func (u *TaskUpsertBulk) SetPriority(v schema.Priority) *TaskUpsertBulk {
 	})
 }
 
+// AddPriority adds v to the "priority" field.
+func (u *TaskUpsertBulk) AddPriority(v schema.Priority) *TaskUpsertBulk {
+	return u.Update(func(s *TaskUpsert) {
+		s.AddPriority(v)
+	})
+}
+
 // UpdatePriority sets the "priority" field to the value that was provided on create.
 func (u *TaskUpsertBulk) UpdatePriority() *TaskUpsertBulk {
 	return u.Update(func(s *TaskUpsert) {