Sorbet: Kernel methods not avaiable for mixin modules

[bmalinconico]

Input

→ View on sorbet.run

# typed: true
module Foo
  def bar
    raise 'foo'
  end
end

class Fooer
  include Foo
end

Fooer.new.bar # Raises an error when run

Observed output

editor.rb:4: Method raise does not exist on Foo https://srb.help/7003
     4 |    raise 'foo'
            ^^^^^^^^^^^
  Did you mean to `include Kernel` in this module?
    https://github.com/sorbet/sorbet/tree/90c20f728c528aa4a1a3dc1a137e4c9eae95716d/rbi/core/kernel.rbi#L870: Did you mean: Kernel#raise?
     870 |  def raise(arg0=T.unsafe(nil), arg1=T.unsafe(nil), arg2=T.unsafe(nil)); end
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Errors: 1

In real execution this code is perfectly valid, the call to the mixed-in method will raise an error.

Expected behavior

No error when running typecheck

Depending on the underlying system, this may be the same root cause as https://github.com/sorbet/sorbet/issues/397

[elliottt]

You should just need to include Kernel in the definition of module Foo to resolve this error during typechecking. For more information, see including kernel

[bmalinconico]

@elliottt Thanks for linking to that trouble shooting doc, my searching focused on others having the issue with raise not Kernel.

[paracycle]

@bmalinconico The reason why it is this way is because this would fail at runtime (note the subclassing from BasicObject here):

# typed: true
module Foo
  def bar
    raise 'foo'
  end
end

class Baz < BasicObject
  include ::Foo
end

Baz.new.bar 

Basically, Sorbet cannot guarantee that the module would always be included into something that inherits from Object, so it tries to be safe.

[jez]

Because this is expected, documented behavior, I'm closing.