Fix a false negative for Style/RedundantLineContinuation

koic · bbatsov · commit f8aa27ff66ad · 2024-10-31T09:27:10.000+02:00
This PR fixes a false negative for `Style/RedundantLineContinuation`
when there is a line continuation at the EOF.
diff --git a/changelog/fix_a_false_negative_for_style_redundant_line_continuation.md b/changelog/fix_a_false_negative_for_style_redundant_line_continuation.md
@@ -0,0 +1 @@
+* [#13401](https://github.com/rubocop/rubocop/pull/13401): Fix a false negative for `Style/RedundantLineContinuation` when there is a line continuation at the EOF. ([@koic][])
diff --git a/lib/rubocop/cop/style/redundant_line_continuation.rb b/lib/rubocop/cop/style/redundant_line_continuation.rb
@@ -69,6 +69,8 @@ class RedundantLineContinuation < Base
         extend AutoCorrector
 
         MSG = 'Redundant line continuation.'
+        LINE_CONTINUATION = "\\\n"
+        LINE_CONTINUATION_PATTERN = /(\\\n)/.freeze
         ALLOWED_STRING_TOKENS = %i[tSTRING tSTRING_CONTENT].freeze
         ARGUMENT_TYPES = %i[
           kFALSE kNIL kSELF kTRUE tCONSTANT tCVAR tFLOAT tGVAR tIDENTIFIER tINTEGER tIVAR
@@ -79,14 +81,16 @@ class RedundantLineContinuation < Base
         def on_new_investigation
           return unless processed_source.ast
 
-          each_match_range(processed_source.ast.source_range, /(\\\n)/) do |range|
+          each_match_range(processed_source.ast.source_range, LINE_CONTINUATION_PATTERN) do |range|
             next if require_line_continuation?(range)
             next unless redundant_line_continuation?(range)
 
             add_offense(range) do |corrector|
               corrector.remove_leading(range, 1)
             end
           end
+
+          inspect_eof_line_continuation
         end
 
         private
@@ -132,6 +136,17 @@ def redundant_line_continuation?(range)
           parse(source.gsub("\\\n", "\n")).valid_syntax?
         end
 
+        def inspect_eof_line_continuation
+          return unless processed_source.raw_source.end_with?(LINE_CONTINUATION)
+
+          rindex = processed_source.raw_source.rindex(LINE_CONTINUATION)
+          line_continuation_range = range_between(rindex, rindex + 1)
+
+          add_offense(line_continuation_range) do |corrector|
+            corrector.remove_trailing(line_continuation_range, 1)
+          end
+        end
+
         def inside_string_literal?(range, token)
           ALLOWED_STRING_TOKENS.include?(token.type) && token.pos.overlaps?(range)
         end
diff --git a/spec/rubocop/cop/style/redundant_line_continuation_spec.rb b/spec/rubocop/cop/style/redundant_line_continuation_spec.rb
@@ -707,4 +707,15 @@ def do_something
         baz)
     RUBY
   end
+
+  it 'registers an offense when there is a line continuation at the EOF' do
+    expect_offense(<<~'RUBY')
+      foo \
+          ^ Redundant line continuation.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      foo#{trailing_whitespace}
+    RUBY
+  end
 end

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+* [#13401](https://github.com/rubocop/rubocop/pull/13401): Fix a false negative for `Style/RedundantLineContinuation` when there is a line continuation at the EOF. ([@koic][])