I assume you mean at https://github.com/ruby/ruby/blob/v2_3_0/vm_method.c#L1915-L.... Agreed it's weird that rb_respond_to will now return true for objects where respond_to is undefined. Though I guess I can see upsides to doing so, and it would require something pretty weird to result in "wrong" behavior.
The case I ran into was in a Rails 4.1 app where ActiveSupport::Duration (which subclassed BasicObject) was used like this: "rand(10.minutes)". That raised an exception in 2.3.0 but worked fine in 2.2.3. The fix was simple - "rand(10.minutes.to_i)". But still, I don't understand it.
Heh...I also ran into an issue with ActiveSupport::Duration, though in my case when passed as the only argument to a method with a signature along the lines of `f(time = 30, [star][star]options)`, with the error involving #to_hash. Since newer versions of ActiveSupport fix it, I didn't look into it too careful (just called #to_i). I'm glad you did!
I'm surprised that I haven't seen anything about that respond_to? change in the blogs; maybe I've just missed it. I might blog this, although I hate ending a post with "gosh I don't know about this one". Makes me feel like I haven't done all my homework.
