Style/IfWithSemicolon - undefined method `source' for nil:NilClass

[snutij]

Hello 👋 I hope I'll give enough information, do not hesitate if you need more context.

Given a file foo.rb:

if 1; elsif 2; end

Which is a valid syntax:

ruby -c foo.rb
Syntax OK

---

Expected behavior

Should not trigger an error, display the offense and propose a fix (reading the code I think this is the expected behavior, not sure to be honest, at least not trigger an error as it's a valid syntax).

Actual behavior

bin/rubocop -d --only Style/IfWithSemicolon foo.rb

An error occurred while Style/IfWithSemicolon cop was inspecting foo.rb:1:0.
undefined method `source' for nil:NilClass
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/style/if_with_semicolon.rb:51:in `correct_elsif'
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/style/if_with_semicolon.rb:39:in `autocorrect'
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/style/if_with_semicolon.rb:32:in `block in on_normal_if_unless'
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/base.rb:377:in `correct'
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/base.rb:181:in `add_offense'
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/style/if_with_semicolon.rb:31:in `on_normal_if_unless'
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/mixin/on_normal_if_unless.rb:10:in `on_if'
/Users/snutij/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/rubocop-1.53.1/lib/rubocop/cop/commissioner.rb:107:in `public_send'

Steps to reproduce the problem

In IfWithSemicolon the on_normal_if_unless receive a node:

(ruby) node
s(:if,
  s(:int, 1), nil,
  s(:if,
    s(:int, 2), nil, nil))

Then to propose a fix the cop calls the correct_elsif, as if node.else_branch&.if_type? is true

(ruby) node.else_branch
s(:if,
  s(:int, 2), nil, nil)
(ruby)  node.else_branch&.if_type?
true

But it's interpolate#{node.if_branch.source} which is nil

(ruby) node.condition.source
"1"
(ruby) node.if_branch
nil

rubocop/lib/rubocop/cop/style/if_with_semicolon.rb

Lines 23 to 34 in aaf1c3f

	def on_normal_if_unless(node)
	return if node.parent&.if_type?
	beginning = node.loc.begin
	return unless beginning&.is?(';')
	message = node.else_branch&.if_type? ? MSG_IF_ELSE : MSG_TERNARY
	add_offense(node, message: format(message, expr: node.condition.source)) do |corrector|
	corrector.replace(node, autocorrect(node))
	end
	end

rubocop/lib/rubocop/cop/style/if_with_semicolon.rb

Lines 38 to 45 in aaf1c3f

	def autocorrect(node)
	return correct_elsif(node) if node.else_branch&.if_type?
	then_code = node.if_branch ? node.if_branch.source : 'nil'
	else_code = node.else_branch ? node.else_branch.source : 'nil'
	"#{node.condition.source} ? #{then_code} : #{else_code}"
	end

rubocop/lib/rubocop/cop/style/if_with_semicolon.rb

Lines 47 to 54 in aaf1c3f

	def correct_elsif(node)
	<<~RUBY.chop
	if #{node.condition.source}
	#{node.if_branch.source}
	#{build_else_branch(node.else_branch).chop}
	end
	RUBY
	end

RuboCop version

bundle exec rubocop -V
1.53.1 (using Parser 3.2.2.3, rubocop-ast 1.29.0, running on ruby 3.2.2) [arm64-darwin22]
  - rubocop-minitest 0.31.0
  - rubocop-rake 0.6.0
  - rubocop-sorbet 0.7.0