Fix regression caused due to removal of select method from CollectionAssociation

- CollectionAssociation#select was removed in
  https://github.com/rails/rails/pull/25989 in favor of
  QueryMethods#select but it caused a regression when passing arguments
  to select and a block.
- This used to work earlier in Rails 4.2 and Rails 5. See gist
  https://gist.github.com/prathamesh-sonpatki/a7df922273473a77dfbc742a4be4b618.
- This commit restores the behavior of Rails 4.2 and Rails 5.0.0 to
  allow passing arguments and block at the same time but also deprecates
  it.
- Because, these arguments do not have any effect on the output of
  select when select is used with a block.
- Updated documentation to remove the example passing arguments and
  block at the same time to `CollectionProxy#select`.

1 files changed, 10 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 9fbbe32e7f..c6d0902e0d 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -242,7 +242,16 @@ module ActiveRecord
     #   Model.select(:field).first.other_field
     #   # => ActiveModel::MissingAttributeError: missing attribute: other_field
     def select(*fields)
-      return super if block_given?
+      if block_given?
+        if fields.any?
+          ActiveSupport::Deprecation.warn(<<-WARNING.squish)
+            When select is called with a block, it ignores other arguments. This behavior is now deprecated and will result in an ArgumentError in Rails 5.1. You can safely remove the arguments to resolve the deprecation warning because they do not have any effect on the output of the call to the select method with a block.
+          WARNING
+        end
+
+        return super()
+      end
+
       raise ArgumentError, "Call this with at least one field" if fields.empty?
       spawn._select!(*fields)
     end