Inconsistent line numbers for Method.source_location

[catlee]

In Ruby 3.4, the following code returns different results depending on which parser is used:

# test.rb
class Foo
  define_method "foo" \
  "bar" do

  end
end

p Foo.instance_method(:foobar).source_location

With ruby --parser=parse.y test.rb I get ["test.rb", 2]
With ruby --parser=prism test.rb I get ["test.rb", 3]
I'm using ruby 3.4.0preview2 (2024-10-07 master 32c733f57b) +PRISM [arm64-darwin23]

[paracycle]

Same behaviour on Ruby 3.4.1 as well:

❯ ruby -v --parser=prism test.rb
ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [arm64-darwin23]
["test.rb", 3]

❯ ruby -v --parser=parse.y test.rb
ruby 3.4.1 (2024-12-25 revision 48d4efcb85) [arm64-darwin23]
["test.rb", 2]

[kddnewton]

I think parse.y is wrong here, the block clearly starts on line 3. I will bring this up for discussion.

[catlee]

I discovered this in the context of fixing a bug in a test plugin which allows you to run tests by line number.

e.g. in code like this:

1 class FooTest < TestCase
2   test "really long" \
3    "test name" do
4    assert ...
5   end
6 end

I think it's reasonable for a developer to want to be able to run the test which starts on line 2.

Rails uses method.source_location and node.start_line to determine which line numbers correspond to test methods: https://github.com/kddnewton/rails/blob/main/railties/lib/rails/test_unit/test_parser.rb#L19