Lint/UselessAssignment must be considered unsafe #14445
Description
Expected behavior
I don't mind if this code has offenses, but this auto-correction is WRONG; must not happen.
It is super-duper difficult -- if not impossible -- to statically prove if a variable assignment is useless or not. Rubocop does not have such feature. That is a reasonable, practical design decision that I support. You should just stop pretending that you do so.
Actual behavior
Autocorrection breaks semantics of the code.
Steps to reproduce the problem
$ cat tmp.rb
def foo
backtrack = []
result = []
node = self
until node.nil?
children = node.children
result << children.first
unless children.second
node = backtrack.pop
next
end
backtrack.push(children[2..]).flatten! if children.third
node = children.second
end
result
end
$
$
$ bin/rubocop --safe-auto-correct tmp.rb
--safe-auto-correct is deprecated; use --autocorrect instead.
Inspecting 1 file
W
Offenses:
tmp.rb:11:7: W: [Corrected] Lint/UselessAssignment: Useless assignment to variable - node.
node = backtrack.pop
^^^^
1 file inspected, 1 offense detected, 1 offense correctedRuboCop version
$ bin/rubocop -V
1.79.0 (using Parser 3.3.9.0, rubocop-ast 1.46.0, analyzing as Ruby 3.2, running on ruby 3.2.4) [x86_64-linux]
- rubocop-faker 1.1.0
- rubocop-performance 1.21.1
- rubocop-rails 2.25.1
- rubocop-rspec 3.0.4