[Fix #14716] Fix infinite loop for Layout/LineLength with SplitStrings

Author: HariprasanthMS

changelog/fix_infinite_loop_for_layout_line_length_with_split_strings.md

@@ -0,0 +1 @@
+* [#14716](https://github.com/rubocop/rubocop/issues/14716): Fix an infinite loop error for `Layout/LineLength` when `SplitStrings` option is enabled and strings span multiple lines. ([@HariprasanthMSH][])

lib/rubocop/cop/layout/line_length.rb

@@ -418,8 +418,11 @@ def largest_possible_string(node)
           # The maximum allowed length of a string value is:
           # `Max` - end delimiter (quote) - continuation characters (space and slash)
           max_length = max - 3
-          # If the string doesn't start at the beginning of the line, the max length is offset
-          max_length -= column_offset_between(node.loc, node.parent.loc) if node.parent
+          # If the string is on the same line as its parent, offset by the column difference
+          # (Only apply when on same line to avoid negative offsets for multi-line dstr)
+          if same_line?(node, node.parent)
+            max_length -= column_offset_between(node.loc, node.parent.loc)
+          end
           node.source[0...(max_length)]
         end
       end

spec/rubocop/cli/autocorrect_spec.rb

@@ -4178,4 +4178,30 @@ class MyClass
     end
     RUBY
   end
+
+  it 'does not cause an infinite loop for Layout/LineLength with SplitStrings' do
+    create_file('.rubocop.yml', <<~YAML)
+      Layout/LineLength:
+        Enabled: true
+        Max: 30
+        SplitStrings: true
+    YAML
+
+    source_file = Pathname('example.rb')
+    create_file(source_file, <<~RUBY)
+      _const = '000000000000000 0000000000000000000000000000 000000000000000000000000000'
+    RUBY
+
+    status = cli.run(['--autocorrect-all'])
+    expect(status).to eq(0)
+    expect($stderr.string).to eq('')
+    expect(source_file.read).to eq(<<~RUBY)
+      # frozen_string_literal: true
+
+      _const = '000000000000000 ' \\
+      '00000000000000000000000000' \\
+      '00 ' \\
+      '000000000000000000000000000'
+    RUBY
+  end
 end

spec/rubocop/cop/layout/line_length_spec.rb

@@ -1058,6 +1058,24 @@ def method_definition_that_is_just_under_the_line_length_limit(foo) # rubocop:di
               end
             end
           end
+
+          context 'when the string has no spaces and spans multiple words with `Max` set to 30' do
+            let(:cop_config) { super().merge('Max' => 30) }
+
+            it 'registers an offense and corrects by splitting the string' do
+              expect_offense(<<~RUBY)
+                _const = '000000000000000 0000000000000000000000000000 000000000000000000000000000'
+                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Line is too long. [83/30]
+              RUBY
+
+              expect_correction(<<~'RUBY')
+                _const = '000000000000000 ' \
+                '00000000000000000000000000' \
+                '00 ' \
+                '000000000000000000000000000'
+              RUBY
+            end
+          end
         end
 
         context 'when SplitStrings: false' do