Line numbers in backtrace with multiline method invocation are sometimes different from CRuby

[yujinakayama]

When there's a method invocation with multiline method invocation as an argument:

def do_something(*)
  raise
end

begin
  do_something(Object # Line 6
               .new)  # Line 7
rescue => error
  puts error.backtrace
end

... JRuby reports the following backtrace:

test.rb:2:in `do_something'
test.rb:7:in `<main>'

... in contrast to CRuby:

test.rb:2:in `do_something'
test.rb:6:in `<main>'

Environment

$ jruby -v
jruby 9.1.10.0 (2.3.3) 2017-05-25 b09c48a Java HotSpot(TM) 64-Bit Server VM 25.25-b02 on 1.8.0_25-b17 +jit [darwin-x86_64]
$ uname -a
Darwin macbookpro.local 16.6.0 Darwin Kernel Version 16.6.0: Fri Apr 14 16:21:16 PDT 2017; root:xnu-3789.60.24~6/RELEASE_X86_64 x86_64

Expected Behavior

With the following script:

def do_something(*)
  raise
end

def print_error_line(error)
  line_number = error.backtrace[1].split(':')[1].to_i
  p File.read(__FILE__).lines[line_number - 1]
end

puts "RUBY_ENGINE: #{RUBY_ENGINE}"
puts "RUBY_VERSION: #{RUBY_VERSION}"
puts "JRUBY_VERSION: #{JRUBY_VERSION}" if defined?(JRUBY_VERSION)

begin
  do_something(Object
               .new)
rescue => error
  puts '=' * 40
  puts error.backtrace
  print_error_line(error)
end

Backtrace should include the beginning line number of the method invocation (the do_something line), as CRuby does:

$ ruby test.rb
RUBY_ENGINE: ruby
RUBY_VERSION: 2.4.1
========================================
test.rb:2:in `do_something'
test.rb:15:in `<main>'
"  do_something(Object\n"

Actual Behavior

JRuby 9.1.10.0 reports backtrace including the last line number of the method invocation (the .new) line):

$ ruby test.rb
RUBY_ENGINE: jruby
RUBY_VERSION: 2.3.3
JRUBY_VERSION: 9.1.10.0
========================================
test.rb:2:in `do_something'
test.rb:16:in `<main>'
"               .new)\n"

[enebo]

Most interestingly (for me) is that the AST is correct:

        FCallNode:do_something 5
          ArrayNode 5
            CallNode:new 6
              ConstNode:Object 6

If I look at the IR I can see one line_num 6 (which will display 7) combing from the Object.new but no line_num 5 after the .new call.

[enebo]

Fixed in commit d7d063d. I accidentally referred to the wrong commit number and since I pushed it I do not want to ammend.

There is a general issue in our IRBuilder where a parent level node when built will indicate that it is a newline node and that it changes the line number....but it has children which also are newline nodes which want to change the line number. So the parent line_num instr is ommitted. I corrected this for fcall nodes but I imagine other cases exist. This at least fixes the reported issue...