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Bug #9475

Updated by nobu (Nobuyoshi Nakada) over 3 years ago

Ruby 2.0 appears to have introduced a subtle behavior change in method resolution that persists in 2.1.0.

The attached test case (also visible online at https://gist.github.com/benweint/8791007) is extracted from an actual application, and while I won't defend the need to do something like this, it is clear that the behavior changed in 2.0. Note that this sounds similar to https://bugs.ruby-lang.org/issues/9236 but is in fact distinct - the test case given in that bug was fixed in Ruby 2.1.

Steps to reproduce:
1. Run the attached testcase on Ruby 1.9.3 note the output
2. Run the attached testcase on Ruby 2.0.0-p353 or 2.1.0-p0, and note the output

Expected results:
While it's certainly not obvious to me what 'should' happen when executing this code, on 1.9.3, it produces this output:

~~~
foo from C
foo from B
foo from A
~~~



Actual results:
On 2.0+, I get this instead

~~~
foo from C
foo from B
foo from B (again)
foo from B
foo from B (again)
foo from B
... previous two lines repeated many times ...
test.rb:11: stack level too deep (SystemStackError)
~~~


That is to say, on 2.0, we get into an infinitely recursive loop that doesn't happen with 1.9.3.

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