[ruby-core:104111] [Ruby master Bug#17887] Missed constant lookup after prepend

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


jeremyevans0 (Jeremy Evans) wrote in #note-3:
> This is because unlike method tables, constant tables are not moved to origin classes.  

Do we know if this was somehow intentional or more like an oversight/incorrect optimization? I would think the latter.

> This behavior has been present since origin classes were added in Ruby 2.0. 

Weren't origin classes introduced at the same time than `prepend`, specifically to implement `prepend`?

> I submitted a pull request to work around this: https://github.com/ruby/ruby/pull/4538

Thanks!



----------------------------------------
Bug #17887: Missed constant lookup after prepend
https://bugs.ruby-lang.org/issues/17887#change-92284

* Author: bjfish (Brandon Fish)
* Status: Open
* Priority: Normal
* ruby -v: 2.6.x-3.0.x
* 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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