From: eregontp@...
Date: 2021-05-25T13:45:53+00:00
Subject: [ruby-core:104035] [Ruby master Bug#17887] Missed constant lookup	after prepend

Issue #17887 has been updated by Eregon (Benoit Daloze).


In the ancestors, `M` is before `A`, so this seems like a bug:
```
B.ancestors # => [B, M, A, Object, Kernel, BasicObject]
```

Also note that with `B.include M`, which reports the same ancestors, it works as expected:
```ruby
module M
  FOO = 'm'
end
class A
  FOO = 'a'
end
class B < A
  def foo
    FOO
  end
end
b = B.new
p b.foo # => "a"
B.include M # instead of A.prepend M
p b.foo # => "m"
```

----------------------------------------
Bug #17887: Missed constant lookup after prepend
https://bugs.ruby-lang.org/issues/17887#change-92173

* Author: bjfish (Brandon Fish)
* Status: Open
* Priority: Normal
* ruby -v: 3.0.0
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
**Description**
The following shows that the constant lookup from B does not find the constant in the prepended M module.  I would expect this lookup to behave like "B.include M" which does print the constant from module M.


**Example**
``` ruby
module M
  FOO = 'm'
end
class A
  FOO = 'a'
end
class B < A
  def foo
    FOO
  end
end
b = B.new
p b.foo
A.prepend M
p b.foo
```
**Expected Result**
```
"a"
"m"
```
**Actual Result**
```
"a"
"a"
```




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