Bug #7554: TracePoint#defined_class doesn't return Class or Module

• Status: Closed
• Assignee: ko1 (Koichi Sasada)
• Target version: 2.0.0
• ruby -v: ruby 2.0.0dev (2012-12-01 trunk 38127) [i386-mswin32_100]

[ko1 (Koichi Sasada)]

In some case (using singleton method),
TracePoint#defined_class doesn't return Class or Module.

example

def self.foo
end

obj = Object.new

def obj.foo
end

module M
def baz
end
end

class C
include M
def self.bar
end
end

TracePoint.trace(:call){|tp|
p [tp.defined_class, tp.defined_class.kind_of?(Module)]
}

foo
obj.foo
C.bar
C.new.baz

#=>

ruby 2.0.0dev (2012-12-01 trunk 38127) [i386-mswin32_100]

[main, false]
[#Object:0x2d8267c, false]
[C, true]
[M, true]

The name `defined_class' expected to return object of Class or Module.
So it should be return Class or Module.

Current code returns modified object by singleton class.
I propose to return singleton class directly.

The following patch fixes this issue.

Index: vm_trace.c

--- vm_trace.c (revision 38362)
+++ vm_trace.c (working copy)
@@ -712,9 +712,6 @@
if (RB_TYPE_P(trace_arg->klass, T_ICLASS)) {
trace_arg->klass = RBASIC(trace_arg->klass)->klass;
}

•   else if (FL_TEST(trace_arg->klass, FL_SINGLETON)) {
  

•   trace_arg->klass = rb_iv_get(trace_arg->klass, "__attached__");
  

•   }
  

  }
  else {
  trace_arg->klass = Qnil;

After that, that script shows:

[#<Class:#Object:0x874b244>, true]
[#<Class:#Object:0x873f9a8>, true]
[#Class:C, true]
[M, true]

The current behavior is from `set_trace_func' (6th parameter of block).
I'm not sure why it returns modified object instead of singleton class.

I believe TracePoint#defined_class should return singleton class directly.
TracePoint is introduced from 2.0, so no compatibility issue.

[ko1 (Koichi Sasada)]

• Description updated (diff)

[ko1 (Koichi Sasada)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r38430.
Koichi, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• vm_trace.c (fill_id_and_klass): TracePoint#defined_class returns
  singleton class. set_trace_func' passed attached class (which is attached/modified by singleton class) by 6th block parameter if it is singleton class. Previous behavior follows this spec. However, this method named defined_class' should return singleton
  class directly because singleton methods are defined in singleton
  class. There are no compatible issue because TracePoint is introduced
  after 2.0.
  But compatiblity with set_trace_func' is brokne. This means that you can not replace all set_trace_func' code with TracePoint
  without consideration of this behavior.
  [Bug #7554]
• test/ruby/test_settracefunc.rb: change a test to catch up
  an above chagne.