[ruby-core:108237] [Ruby master Bug#18730] Double `return` event handling with different tracepoints
From:
"hurricup (Alexandr Evstigneev)" <noreply@...>
Date:
2022-04-14 14:50:37 UTC
List:
ruby-core #108237
Issue #18730 has been reported by hurricup (Alexandr Evstigneev).
----------------------------------------
Bug #18730: Double `return` event handling with different tracepoints
https://bugs.ruby-lang.org/issues/18730
* Author: hurricup (Alexandr Evstigneev)
* Status: Open
* Priority: Normal
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
I'm not sure if this is a bug or intentional behavior, but feels a bit unexpected. Ruby 3.0.x, 3.1.x affected.
Here is the script demonstrating the issue:
```
def bar
42 #bp here
end
tp_line = TracePoint.new(:line) do |tp0|
puts "Got line event from #{tp0.path}:#{tp0.lineno}"
tp_multi1 = TracePoint.new(:return, :b_return, :line) do |tp|
if tp.lineno == 3
puts "Got first return `#{tp.event}` from #{tp.path}:#{tp.lineno}"
tp.disable
tp_multi2 = TracePoint.new(:return, :b_return, :line) do |tps|
puts "Got second return `#{tps.event}` from #{tps.path}:#{tps.lineno}"
end
tp_multi2.enable(target: RubyVM::InstructionSequence.of(method :bar))
end
end
tp_multi1.enable
end
tp_line.enable(target: RubyVM::InstructionSequence.of(method :bar))
bar
```
1. We set a line TP to the `bar` method `iseq` (consider it a line breakpoint)
2. When line event is triggered we setting another untargeted tracepoint for the same method, to catch `line`, `return` and `b_return` events (consider it attempt to step into something)
3. When return event of the `bar` method is triggered, we disabling second tracepoint and setting another one, targeted to the same method and multiple events.
Output i get:
```
Got line event from /home/hurricup/test.rb:2
Got first return `return` from /home/hurricup/test.rb:3
Got second return `return` from /home/hurricup/test.rb:3
```
The question is: why return triggered on the second tracepoint, when we already handeled it?
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