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Bug #15578

closed

Missing TracePoint return event when a conditional is used before a rescue

Added by zetter (Chris Zetter) over 2 years ago. Updated about 2 years ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Target version:
-
[ruby-core:91366]

Description

Hello, I've been using TracePoint on a Ruby on Rails project and noticed that the number of method 'return' events was less than the number of 'call' events. An example of a return event that isn't always logged (depending on inputs) is the _decrypt method - https://github.com/rails/rails/blob/v5.2.2/activesupport/lib/active_support/message_encryptor.rb#L183

I've made a simplified example based on this method. There are other methods that don't have exact same structure but show the same problem. I haven't yet been able to make reproducible examples for them.

Running the following code with TracePoint doesn't emit the 'return' event as expected:

def example
  1 if 1 == 1
rescue
end

example()

Here are the events that are logged using TracePoint:

[nil, :line]
[:example, :call]
[:example, :line]

I expect it log the return even from the example method:

[nil, :line]
[:example, :call]
[:example, :line]
[:example, :return]

I have attached a runnable example.

This bug looks like it was introduced between 2.5.3 and 2.6.0. It works as expected on 2.5.3, and it occurs on 2.6.0 and 2.6.1

I've also tried compiling the instructions without peephole optimisation on and the bug no longer occurs.


Files

example.rb (249 Bytes) example.rb zetter (Chris Zetter), 01/31/2019 04:16 PM

Related issues

Related to Ruby master - Bug #15911: Missing TracePoint return event for ||=ClosedActions
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