do not compute table names for abstract classes

[amatsuda]

I found a trivial inconsistency on AR table_name computing behavior.

While there are an abstract_class model and its child:

class User < ActiveRecord::Base
  self.abstract_class = true
end

class Admin < User
end

The child's table_name changes depending on whether the abstract model's table_name were called or not.

User.table_name
=> "users"
User.scoped.to_sql
=> SELECT "users".* FROM "users"
Admin.table_name
=> "users"
Admin.scoped.to_sql
=> SELECT "users".* FROM "users"

Admin.table_name
=> "admins"
Admin.scoped.to_sql
=> SELECT "admins".* FROM "admins"

This doesn't matter for normal use, but sometimes causes weird errors, for example, when dealing with an AR extension plugin that scans through descendants of AR::Base on Railtie hook.

Here's a patch that makes abstract models always skip compute_table_name.

[amatsuda]

Thank you @tenderlove!
Can you please backport this to 3-1-stable?

[tenderlove]

@amatsuda done!

[amatsuda]

@tenderlove Thank you!

[route]

What about scopes?

class User < ActiveRecord::Base
  self.abstract_class = true
  scope :something, where(:name => 'something')
end

class Admin < User
end

Admin.something.to_sql => "SELECT \"admins\".* FROM \"admins\"  WHERE \"\".\"name\" = 'something'"

And we have missed table name in where statment