rails: Aggregate methods (empty?, any?, count) generate invalid SQL

NOTE the two tests above are similar. Only tThe assertions order is different. One is probably passing only because it has fetched the data on the rel while the other needs to use SQL COUNT to return the result for #empty?.

It could be related to #12405.

gem 'activerecord', '4.1.0.beta1'
require 'active_record'
require 'minitest/autorun'
require 'logger'

ActiveRecord::Base.logger = Logger.new(STDOUT)
ActiveRecord::Base.establish_connection(
  :adapter  => 'postgresql',
  :database => 'x'
)

ActiveRecord::Schema.define do
  create_table :blogs, :force => true do |t|
    t.string :name
  end
end

class Blog < ActiveRecord::Base
end

class TestMe < MiniTest::Unit::TestCase
  def test_empty_then_to_a
    rel = Blog.select("blogs.*, 1234 as more")
    assert_equal rel.empty?, true # this fails
    assert_equal rel.to_a, []
  end

  def test_to_a_then_empty
    rel = Blog.select("blogs.*, 1234 as more")
    assert_equal rel.to_a, []
    assert_equal rel.empty?, true
  end
end

This fails with:

-- create_table(:blogs, {:force=>true})
D, [2014-01-09T17:10:07.364506 #21686] DEBUG -- :    (1.5ms)  DROP TABLE "blogs"
D, [2014-01-09T17:10:07.366782 #21686] DEBUG -- :    (2.1ms)  CREATE TABLE "blogs" ("id" serial primary key, "name" character varying(255)) 
   -> 0.0171s
MiniTest::Unit::TestCase is now Minitest::Test. From tmp/test-eager.rb:21:in `<main>'
Run options: --seed 22020

# Running:

D, [2014-01-09T17:10:07.438523 #21686] DEBUG -- :    (0.2ms)  SELECT COUNT(blogs.*, 1234 as more) FROM "blogs"
E, [2014-01-09T17:10:07.438591 #21686] ERROR -- : PG::SyntaxError: ERROR:  syntax error at or near "as"
LINE 1: SELECT COUNT(blogs.*, 1234 as more) FROM "blogs"
                                   ^
: SELECT COUNT(blogs.*, 1234 as more) FROM "blogs"
ED, [2014-01-09T17:10:07.439088 #21686] DEBUG -- :   Blog Load (0.2ms)  SELECT blogs.*, 1234 as more FROM "blogs"
.

Finished in 0.006772s, 295.3337 runs/s, 295.3337 assertions/s.

  1) Error:
TestMe#test_empty_then_to_a:
ActiveRecord::StatementInvalid: PG::SyntaxError: ERROR:  syntax error at or near "as"
LINE 1: SELECT COUNT(blogs.*, 1234 as more) FROM "blogs"
                                   ^
: SELECT COUNT(blogs.*, 1234 as more) FROM "blogs"
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/postgresql_adapter.rb:798:in `exec'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/postgresql_adapter.rb:798:in `block in exec_no_cache'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/abstract_adapter.rb:359:in `block in log'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-4.1.0.beta1/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/abstract_adapter.rb:353:in `log'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/postgresql_adapter.rb:798:in `exec_no_cache'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/postgresql/database_statements.rb:137:in `exec_query'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/postgresql_adapter.rb:920:in `select'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/abstract/database_statements.rb:23:in `select_all'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/connection_adapters/abstract/query_cache.rb:69:in `select_all'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/relation/calculations.rb:254:in `execute_simple_calculation'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/relation/calculations.rb:216:in `perform_calculation'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/relation/calculations.rb:111:in `calculate'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/relation/calculations.rb:26:in `count'
    /Users/dnagir/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-4.1.0.beta1/lib/active_record/relation.rb:251:in `empty?'
    tmp/test-eager.rb:24:in `test_empty_then_to_a'

2 runs, 2 assertions, 0 failures, 1 errors, 0 skips