[ruby-core:91666] [Ruby trunk Bug#14702] On Ruby 2.5.1, tracepoint isn't working on the file that is loaded by load_iseq

[fxn@hashref.com]

Issue #14702 has been updated by fxn (Xavier Noria).


Hi!

Rails 6 applcations have bootsnap and Zeitwerk enabled by default. Right now, that needs Ruby 2.6 because Zeitwerk sets a trace point on the :class event to support what I call "explicit namespaces".

Just wanted to let you know about this situation, in case you'd like to take it into account for the timeline to ship 5.2.4.

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Bug #14702: On Ruby 2.5.1, tracepoint isn't working on the file that is loaded by load_iseq
https://bugs.ruby-lang.org/issues/14702#change-76926

* Author: makoto_tajitsu@hotmail.co.jp (Makoto Tajitsu)
* Status: Closed
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* Target version: 
* ruby -v: ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin16]
* Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: DONE
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On Ruby 2.5.1, when loading file with RubyVM::InstructionSequence.load_from_binary, TracePoint callback event is not working on loaded file.

## Steps to reproduce

Ruby version.
```
$ ruby -v
# => ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin16]
```

The example with `yomikomu` gem which is simply used `load_iseq` and `load_from_binary` method to load file quickly is following.
```ruby
$ YOMIKOMU_AUTO_COMPILE=true bundle exec irb

> TracePoint.trace(:line) { |tp| puts tp.lineno if tp.path == '/path/to/somefile.rb' }
# => #<TracePoint:enabled>

> load '/path/to/somefile.rb'
# 3
# 4
# ...

> require 'yomikomu'

> load '/path/to/somefile.rb'
# no tracepoint callback for line event
```

## Result of reproduce process

tracepoint callback isn't called on loaded file by using load_iseq and load_from_binary.

## Expected result and the reason why you expect

tracepoint callback should be called for any loaded file to debug with debugguer(e.g. byebug).

On Ruby 2.4.3, this example is working correctly, so tracepoint callback is called and output lineno to stdout when loaded file after `require 'yomikomu'`.





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