Bug #13369: TracePoint gives incorrect `return_value` after rescuing error when using `return`

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16]
• Backport: 2.2: WONTFIX, 2.3: DONE, 2.4: DONE

[backus (John Backus)]

In the following example

class Foo
  MyError = Class.new(StandardError)

  def example1
    norf
  rescue MyError => error
    2
  end

  def example2
    norf
  rescue MyError => error
    return 2
  end

  def norf
    raise MyError
  end
end

trace = TracePoint.new(:return) do |tp|
  puts "#{tp.defined_class}##{tp.method_id} RETURNS #{tp.return_value.inspect}"
end

trace.enable

Foo.new.example1 # => 2
puts
Foo.new.example2 # => 2

# >> Foo#norf RETURNS nil
# >> Foo#example1 RETURNS 2
# >> 
# >> Foo#norf RETURNS nil
# >> Foo#example2 RETURNS nil

Both example1 AND example2 return 2. For some reason though, the tracepoint event for example2 says that it returns nil.

[ayemos (Yuichiro Someya)]

• File diff.patch diff.patch added

By some investigations, it turned out to be caused by the result value passed in hook_before_rewind method .

The return value would be as expected by the batch, but it would fail in some tests.

[ko1 (Koichi Sasada)]

• Status changed from Open to Closed

Applied in changeset trunk|r58262.

---

fix TracePoint#return_value with non-local exits

• vm.c: get return_value from imemo_throw_data object (THROW_DATA_VAL()).
  imemo_throw_data (TAG_BREAK) contains returned value.
  However, imemo_throw_data (TAG_BREAK) can skip several frames so that
  we need to use it only once (at most internal frame). To record it,
  we introduced THROW_DATA_CONSUMED and check it.

• internal.h: define THROW_DATA_CONSUMED flag.

• test/ruby/test_settracefunc.rb: add tests for [Bug #13369]

• vm_insnhelper.h: add THROW_DATA_CONSUMED_P() and
  THROW_DATA_CONSUMED_SET().

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN to 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: REQUIRED

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: REQUIRED to 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: DONE

ruby_2_4 r59296 merged revision(s) 58262,5826.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: DONE to 2.2: WONTFIX, 2.3: REQUIRED, 2.4: DONE

[usa (Usaku NAKAMURA)]

• Backport changed from 2.2: WONTFIX, 2.3: REQUIRED, 2.4: DONE to 2.2: WONTFIX, 2.3: DONE, 2.4: DONE

ruby_2_3 r59547 merged revision(s) 58262,58263.