[Fix rubocop#13202] Fix an incorrect autocorrect for `Style/Combinabl…

…eLoops`

Fixes rubocop#13202.

This PR fixes an incorrect autocorrect for `Style/CombinableLoops`
when looping over the same data with different block variable names.

changelog/fix_an_incorrect_autocorrect_for_style_combinable_loops.md

@@ -0,0 +1 @@
+* [#13202](https://github.com/rubocop/rubocop/issues/13202): Fix an incorrect autocorrect for `Style/CombinableLoops` when looping over the same data with different block variable names. ([@koic][])

lib/rubocop/cop/style/combinable_loops.rb

@@ -7,6 +7,9 @@ module Style
       # can be combined into a single loop. It is very likely that combining them
       # will make the code more efficient and more concise.
       #
+      # NOTE: Autocorrection is not applied when the block variable names differ in separate loops,
+      # as it is impossible to determine which variable name should be prioritized.
+      #
       # @safety
       #   The cop is unsafe, because the first loop might modify state that the
       #   second loop depends on; these two aren't combinable.
@@ -61,16 +64,20 @@ class CombinableLoops < Base
 
         MSG = 'Combine this loop with the previous loop.'
 
+        # rubocop:disable Metrics/CyclomaticComplexity
         def on_block(node)
           return unless node.parent&.begin_type?
           return unless collection_looping_method?(node)
           return unless same_collection_looping_block?(node, node.left_sibling)
           return unless node.body && node.left_sibling.body
 
           add_offense(node) do |corrector|
+            next unless node.arguments == node.left_sibling.arguments
+
             combine_with_left_sibling(corrector, node)
           end
         end
+        # rubocop:enable Metrics/CyclomaticComplexity
 
         alias on_numblock on_block
 

spec/rubocop/cop/style/combinable_loops_spec.rb

@@ -60,6 +60,16 @@
       RUBY
     end
 
+    it 'registers an offense and does not correct when looping over the same data with different block variable names' do
+      expect_offense(<<~RUBY)
+        items.each { |item| foo(item) }
+        items.each { |x| bar(x) }
+        ^^^^^^^^^^^^^^^^^^^^^^^^^ Combine this loop with the previous loop.
+      RUBY
+
+      expect_no_corrections
+    end
+
     it 'registers an offense when looping over the same data for the third consecutive time with numbered blocks' do
       expect_offense(<<~RUBY)
         items.each { foo(_1) }