to_sql does not work as intended when as is used.

[fdeschenes]

Without as, works as intended

2.1.0 :001 > Post.where(id: 2).to_sql
 => "SELECT \"posts\".* FROM \"posts\" WHERE \"posts\".\"id\" = 2" 

With as, does not work as intended

2.1.0 :001 > Post.where(id: 2).as('post').to_sql
 => "(SELECT \"posts\".* FROM \"posts\" WHERE \"posts\".\"id\" = $1) post" 

I expect the returned value to be "(SELECT \"posts\".* FROM \"posts\" WHERE \"posts\".\"id\" = 2) post"

[matthewd]

See #18379; you're (maybe unknowingly) using an Arel method; its return value has some similar methods to AR::Relation, including to_sql... but it's not the same.