This was happening when a `super` call in an overwritten attribute method
was triggering a method_missing fallback, because attribute methods
haven't been generated yet.

  class Topic < ActiveRecord::Base
    def title
      # `super` would re-invoke this method if define_attribute_methods
      # hasn't been called yet resulting in double '!' appending
      super + '!'
    end
  end

for attributes that are columns.

The method itself got extracted out from ActiveRecored::Base in commit
ceb33f84, but the test code never did.

begin
  Topic.new("hello" => "world")
rescue ActiveRecord::UnknownAttributeError => e
  e.record # => #<Topic ... >
  e.attribute # => "hello"
end

This fixes the following behaviour:

    class Person < ActiveRecord::Base
      belongs_to :company
    end

    # Before:
    person = Person.select('id').first
    person[:name]       # => nil
    person.name         # => ActiveModel::MissingAttributeError: missing_attribute: name
    person[:company_id] # => nil
    person.company      # => nil

    # After:
    person = Person.select('id').first
    person[:name]       # => ActiveModel::MissingAttributeError: missing_attribute: name
    person.name         # => ActiveModel::MissingAttributeError: missing_attribute: name
    person[:company_id] # => ActiveModel::MissingAttributeError: missing_attribute: company_id
    person.company      # => ActiveModel::MissingAttributeError: missing_attribute: company_id

Fixes #5433.

This reverts commit 86c3dfbd.

Conflicts:
	activerecord/lib/active_record/attribute_methods/read.rb

Reason: whilst this increased performance, it also presents a DoS risk
via memory exhaustion if users were allowing user input to dictate the
arguments of read/write_attribute. I will investigate alternative ways
to cut down on string allocations here.

All tests with a custom inheritance_column use the `Vegtable` model.
The field ruby_type on the Company models is no longer needed

This is a performance/GC optimisation.

In theory, this could be optimised by the implementation (last time I
checked, this would have no effect on JRuby). But in practise, this make
attribute access faster.

It doesn't serve much purpose now that ActiveRecord::Base.all returns a
Relation.

The code is moved to active_record_deprecated_finders.

All other multiparameter assignment tests are in the same file, so it
makes sense to have all of them here.

does not have TIME data type.

Fixes #6825, adds tests covering cases and error possibilities, also changes SQLite3 driver to correctly generate a time column instead of datetime

This reverts commit fa6d921e.

Reason: Not a fan of such massive changes. We usually close such changes
if made to Rails master as a pull request. Following the same principle
here and reverting.

[ci skip]

For future reference, this is the regex I used: ^\s*#\s*\n(?!\s*#). Replace
with the first match, and voilà! Note that the regex matches a little bit too
much, so you probably want to `git add -i .` and go through every single diff
to check if it actually should be changed.

This reverts commit 7381596e.