Ruby

ObjectSpace.allocation_class_path is an API that returns the class of self in the context where an object was allocated. However, due to recent optimizations in Class#new (#21254), the return value now changes depending on whether TracePoint is enabled.

require "objspace" class Foo def test obj = Object.new ObjectSpace.allocation_class_path(obj) end end ObjectSpace.trace_object_allocations_start p Foo.new.test #=> 3.4.2: "Class", master: "Foo" 

Previously, this returned "Class" (from the Class#new call frame), but in the master branch, the result is now "Foo" because that frame is gone.

I am ok for the incompatibility itself because I find the new behavior more intuitive and useful. However, there's an inconsistency: the optimization is disabled when TracePoint is enabled, causing the result to revert to the old behavior.

p Foo.new.test #=> master: "Foo" TracePoint.new {}.enable do p Foo.new.test #=> master: "Class", expected: "Foo" end 

This makes behavior dependent on whether TracePoint is enabled, which can lead to confusion.

@ko1 (Koichi Sasada) @tenderlovemaking (Aaron Patterson) Can we make ObjectSpace.allocation_class_path consistently return the class from the .new call context, regardless of the TracePoint state?

I am facing a failure of the following test when code coverage (which uses TracePoint) is enabled:

https://github.com/ruby/ruby/blob/e8ad728209ee22136e61054fea74096b49088b8a/test/objspace/test_objspace.rb#L206

As a short-term workaround, I'm considering commenting out this test.