Missing TracePoint return event when a conditional is used before a rescue
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.
Updated by nobu (Nobuyoshi Nakada) about 2 years ago
- Status changed from Open to Closed
Applied in changeset trunk|r66977.
Revert r63383, r63248 "compile.c: copy a short insn with leave"
leave insn, TRACE also should be copied if it is
present, but this optimization is trivial and not worth the
complexity. [ruby-core:91366] [Bug #15578]