Bug #15674
Regression: ObjectSpace.allocation_sourceline produces the wrong location for allocations, it shows the end of the method instead of the line where the object was created
Description
Originally I opened this up as an issue in memory profiler https://github.com/SamSaffron/memory_profiler/issues/67, however I was able to isolate the issue to just Ruby 2.6.
ObjectSpace.allocation_sourceline is reporting the line where a method ends rather than the line where the object was actually allocated.
Here's the script. You would expect that object space would tell me the allocation happens on line 2 but instead it gets reported as line 3:
def my_concat(a, b) return a + b # <==================== end require 'fileutils' require 'objspace' FileUtils.mkdir_p("tmp") def run ObjectSpace.trace_object_allocations do 10.times do my_concat("hello".freeze, "world".freeze) end 10.times do my_concat("hello".freeze, "world".freeze) end end ObjectSpace.each_object do |obj| file = ObjectSpace.allocation_sourcefile(obj) line = ObjectSpace.allocation_sourceline(obj) next unless file && line puts "#{file}:#{line}" end end run
If you add space to the method body it keeps incrementing the line number of the output. For example, changing the method body to this, should not change the allocation location:
def my_concat(a, b)
return a + b # <====================
end
However, it is reported as a different line:
script.rb:8
I tested with Ruby 2.3, 2.4, and 2.5 and all those versions produce a correct result, this regression is limited to only 2.6.