Lint/EmptyConditionalBody does not allow commented empty body in 2nd elsif

[r7kamura]

Expected behavior

In Lint/EmptyConditionalBody, when AllowComments: true, no offense should be detected from the following code:

if condition1
  do_something1
elsif condition2
  do_something2
elsif condition3
  # noop
end

Actual behavior

Lint/EmptyConditionalBody detects an offense like this:

elsif condition2
  do_something2
elsif condition3
+^^^^^^^^^^^^^^^^ Avoid `elsif` branches without a body.
  # noop
end

Steps to reproduce the problem

This behavior can be reproduced by applying the following patch:

diff --git a/spec/rubocop/cop/lint/empty_conditional_body_spec.rb b/spec/rubocop/cop/lint/empty_conditional_body_spec.rb
index edd5cda13..8ceea38f8 100644
--- a/spec/rubocop/cop/lint/empty_conditional_body_spec.rb
+++ b/spec/rubocop/cop/lint/empty_conditional_body_spec.rb
@@ -75,6 +75,18 @@ RSpec.describe RuboCop::Cop::Lint::EmptyConditionalBody, :config do
     RUBY
   end
 
+  it 'does not register an offense for missing 2nd `elsif` body with a comment' do
+    expect_no_offenses(<<~'RUBY')
+      if condition1
+        do_something1
+      elsif condition2
+        do_something2
+      elsif condition3
+        # noop
+      end
+    RUBY
+  end
+
   it 'registers an offense for missing `elsif` body' do
     expect_offense(<<~RUBY)
       if condition

RuboCop version

$ bundle exec rubocop -V
1.50.2 (using Parser 3.2.2.1, rubocop-ast 1.28.0, running on ruby 3.1.3) [x86_64-linux]
  - rubocop-performance 1.17.1
  - rubocop-rake 0.6.0
  - rubocop-rspec 2.20.0

[r7kamura]

I think the reason for this bug is that the parent of the second elsif is the first elsif, and this first elsif does not have location.end, so it fails to compute the line number and consequently does not recognize the comment.

rubocop/lib/rubocop/cop/mixin/comments_help.rb

Lines 18 to 23 in b246658

	def comments_in_range(node)
	start_line = node.source_range.line
	end_line = find_end_line(node)
	processed_source.each_comment_in_lines(start_line...end_line)
	end

rubocop/lib/rubocop/cop/mixin/comments_help.rb

Lines 62 to 78 in b246658

	# Returns the end line of a node, which might be a comment and not part of the AST
	# End line is considered either the line at which another node starts, or
	# the line at which the parent node ends.
	# rubocop:disable Metrics/AbcSize
	def find_end_line(node)
	if node.if_type? && node.loc.else
	node.loc.else.line
	elsif (next_sibling = node.right_sibling)
	next_sibling.loc.line
	elsif (parent = node.parent)
	parent.loc.end ? parent.loc.end.line : parent.loc.line
	else
	node.loc.end.line
	end
	end
	# rubocop:enable Metrics/AbcSize
	end