[ruby-core:68896] [Ruby trunk - Bug #10702] Constant look up inconsistency with constants defined in included modules

Issue #10702 has been updated by Jack Nagel.


>I don't get why X::B works though as it is not within X and therefor does not get to take advantage of X's ancestry lookup.

It is through ancestry. Among other things, including A in X includes A's constants in X. (see the documentation for `Module#include`/`Module.append_features`) 

```ruby
module A; module B; end; end
module X; include A; end

X.const_defined?(:B) # => true
X.const_defined?(:B, false) # => false

module X
  puts B # => this works because X includes A, which defines B.

  module Y
    puts B # => this is an error because (a) Y does not share ancestry with X and (b) B is not defined in the current nesting.
  end
end
```



----------------------------------------
Bug #10702: Constant look up inconsistency with constants defined in included modules
https://bugs.ruby-lang.org/issues/10702#change-52163

* Author: Kelly Stannard
* Status: Rejected
* Priority: Normal
* Assignee: 
* ruby -v: 2.2-head
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
https://gist.github.com/kwstannard/c0f722976ba023cc5755

```ruby
module A
  module B
  end
end

module C
  include A

  puts B.inspect # => A::B

  class D
    puts B.inspect rescue puts 'failed' # => failed
  end

  B = B

  class E
    puts B.inspect # => A::B
  end
end
```

When you include a module you gain access to that module's constants as seen in line 9. Line 19 shows that you can get constants defined in the nested module when the constant is defined within the module itself.

Line 12 is the bug. Shouldn't class `D` be able to access module `B` since the previous line shows that module `C` has access to Module `B`?



-- 
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