def raise_func
  raise "noise"
end

def err_func
  raise_func
end

def use_some_more_stack
  puts "used some more stack"
end

def use_some_stack
  puts "used some stack"
  use_some_more_stack
end

def func1
  begin
    err_func
  rescue => e
    use_some_stack
    e.backtrace.each { |entry|
      p entry
    }
  end
end

def func2
  begin
    err_func
  rescue => e
    e.backtrace.each { |entry|
      p entry
    }
  end
end


func1
func2

$>ruby broken_backtrace.rb
used some stack
used some more stack
"broken_backtrace.rb:2:in raise_func"
"broken_backtrace.rb:6:in err_func"
"broken_backtrace.rb:20:in func1"
"broken_backtrace.rb:40:in main"
"broken_backtrace.rb:2:in raise_func"
"broken_backtrace.rb:6:in err_func"
"broken_backtrace.rb:31:in func2"
"broken_backtrace.rb:41:in main"

$>mruby broken_backtrace.rb
used some stack
used some more stack
"broken_backtrace.rb:10:in Object.use_some_more_stack"
"broken_backtrace.rb:23:in Object.func1"
"broken_backtrace.rb:40"
"broken_backtrace.rb:2:in Object.raise_func"
"broken_backtrace.rb:33:in Object.func2"
"broken_backtrace.rb:41

I see several discrepancies:

1. err_func is not mentioned in the backtraces given by mruby
2. line numbers differ for 'func1' and 'func2' entries between mruby and ruby
3. in backtrace for 'func1', 'raise_func' is replaced by 'use_some_more_stack' even though it was not on the call stack when the exception was thrown, but was called right before printing the backstack