Exceptions raised from a :call tracepoint can sometimes be "rescued" inside the method
This is a Ruby 2.5 regression.
If you raise an exception from a :call tracepoint, it can, in certain circumstances, be caught by a rescue block inside the called method. Here is an illustration:
def foo begin puts "hi" rescue => e puts "In rescue" end end TracePoint.trace :call do |tp| raise "kaboom" if tp.method_id == :foo end foo
In Ruby 2.4.3, this results in the exception as expected.
In Ruby 2.5.0, this results in "in rescue" being printed to the console. The rescue block inside method "foo" is catching the exception.
This is highly dependent on the positioning of the rescue block in the method, and may be related to which bytecode is flagged with the trace flag. For example, the following method "foo" raises the exception in Ruby 2.5.0:
def foo puts "hi" begin puts "hi" rescue => e puts "In rescue" end end
Here are three more interesting variants that should be considered:
def foo if true begin puts "hi" rescue => e puts "In rescue" end end end
Prints "in rescue"
def foo if false begin puts "hi" rescue => e puts "In rescue" end end end
Raises the exception
def foo if false begin puts "hi" rescue => e puts "In rescue" end end 1 end
Updated by ko1 (Koichi Sasada) about 1 year ago
- Status changed from Open to Rejected
I want to reject this issue because of the following reasons:
- TracePoint block shouldn't raise an exception. TracePoint should not hurt non-hook (99.99..% case) execution if possible. I don't think this difference is not a matter.
- Now Ruby 2.4 is obsolete version (current last supported version is Ruby 2.6), so it also the change from stable versions if it was changed. I propose to change the definition of
callevent is "It invokes just before the first line in a method" from Ruby 2.4.
def foo # invoike here before 2.4 begin # invoke here from 2.5 foo rescue ... end end
Please reopen this issue if it is needed.