This method is deprecated or moved on the latest stable version.
The last existing version (v4.2.9) is shown here.
source_macro()
public
The macro used by the source association
# File activerecord/lib/active_record/reflection.rb, line 763
def source_macro
ActiveSupport::Deprecation.warn( ActiveRecord::Base.source_macro is deprecated and will be removed without replacement..squish)
source_reflection.source_macro
end