[Fix rubocop#10791] Fix an incorrect autocorrect for Style/Semicolon

Fixes rubocop#10791.

This PR fixes an incorrect autocorrect for `Style/Semicolon`
when using endless range before semicolon.

changelog/fix_an_incorrect_autocorrect_for_style_semicolon.md

@@ -0,0 +1 @@
+* [#10791](https://github.com/rubocop/rubocop/issues/10791): Fix an incorrect autocorrect for `Style/Semicolon` when using endless range before semicolon. ([@koic][])

lib/rubocop/cop/style/semicolon.rb

@@ -31,6 +31,7 @@ class Semicolon < Base
         extend AutoCorrector
 
         MSG = 'Do not use semicolons to terminate expressions.'
+        REGEXP_DOTS = %i[tDOT2 tDOT3].freeze
 
         def self.autocorrect_incompatible_with
           [Style::SingleLineMethods]
@@ -39,6 +40,10 @@ def self.autocorrect_incompatible_with
         def on_new_investigation
           return if processed_source.blank?
 
+          ast = processed_source.ast
+          @range_nodes = ast.range_type? ? [ast] : []
+          @range_nodes.concat(ast.each_descendant(:irange, :erange).to_a)
+
           check_for_line_terminator_or_opener
         end
 
@@ -64,12 +69,14 @@ def check_for_line_terminator_or_opener
           # Make the obvious check first
           return unless processed_source.raw_source.include?(';')
 
-          each_semicolon { |line, column| register_semicolon(line, column, false) }
+          each_semicolon do |line, column, token_before_semicolon|
+            register_semicolon(line, column, false, token_before_semicolon)
+          end
         end
 
         def each_semicolon
           tokens_for_lines.each do |line, tokens|
-            yield line, tokens.last.column if tokens.last.semicolon?
+            yield line, tokens.last.column, tokens[-2] if tokens.last.semicolon?
             yield line, tokens.first.column if tokens.first.semicolon?
           end
         end
@@ -78,13 +85,21 @@ def tokens_for_lines
           processed_source.tokens.group_by(&:line)
         end
 
-        def register_semicolon(line, column, after_expression)
+        def register_semicolon(line, column, after_expression, token_before_semicolon = nil)
           range = source_range(processed_source.buffer, line, column)
 
           add_offense(range) do |corrector|
             if after_expression
               corrector.replace(range, "\n")
             else
+              # Prevents becoming one range instance with subsequent line when endless range
+              # without parentheses.
+              # See: https://github.com/rubocop/rubocop/issues/10791
+              if REGEXP_DOTS.include?(token_before_semicolon&.type)
+                range_node = find_range_node(token_before_semicolon)
+                corrector.wrap(range_node, '(', ')') if range_node
+              end
+
               corrector.remove(range)
             end
           end
@@ -103,6 +118,12 @@ def find_semicolon_positions(line)
             yield Regexp.last_match.begin(0)
           end
         end
+
+        def find_range_node(token_before_semicolon)
+          @range_nodes.detect do |range_node|
+            range_node.source_range.contains?(token_before_semicolon.pos)
+          end
+        end
       end
     end
   end

spec/rubocop/cop/style/semicolon_spec.rb

@@ -108,6 +108,76 @@ module Foo; end
     expect_correction(" puts 1\n")
   end
 
+  it 'registers an offense for range (`1..42`) with semicolon' do
+    expect_offense(<<~RUBY)
+      1..42;
+           ^ Do not use semicolons to terminate expressions.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      1..42
+    RUBY
+  end
+
+  it 'registers an offense for range (`1...42`) with semicolon' do
+    expect_offense(<<~RUBY)
+      1...42;
+            ^ Do not use semicolons to terminate expressions.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      1...42
+    RUBY
+  end
+
+  context 'Ruby >= 2.6', :ruby26 do
+    it 'registers an offense for endless range with semicolon (irange only)' do
+      expect_offense(<<~RUBY)
+        42..;
+            ^ Do not use semicolons to terminate expressions.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        (42..)
+      RUBY
+    end
+
+    it 'registers an offense for endless range with semicolon (irange and erange)' do
+      expect_offense(<<~RUBY)
+        42..;
+            ^ Do not use semicolons to terminate expressions.
+        42...;
+             ^ Do not use semicolons to terminate expressions.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        (42..)
+        (42...)
+      RUBY
+    end
+
+    it 'registers an offense for endless range with semicolon in the method definition' do
+      expect_offense(<<~RUBY)
+        def foo
+          42..;
+              ^ Do not use semicolons to terminate expressions.
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        def foo
+          (42..)
+        end
+      RUBY
+    end
+
+    it 'does not register an offense for endless range without semicolon' do
+      expect_no_offenses(<<~RUBY)
+        42..
+      RUBY
+    end
+  end
+
   context 'with a multi-expression line without a semicolon' do
     it 'does not register an offense' do
       expect_no_offenses(<<~RUBY)