Merge pull request #12378 from koic/fix_a_false_negative_for_style_se…

…micolon Fix a false negative for `Style/Semicolon`
rubocop · Nov 10, 2023 · e17d887 · e17d887
2 parents 95b0290 + cee4694
commit e17d887
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diff --git a/changelog/fix_a_false_negative_for_style_semicolon.md b/changelog/fix_a_false_negative_for_style_semicolon.md
@@ -0,0 +1 @@
+* [#12378](https://github.com/rubocop/rubocop/pull/12378): Fix a false negative for `Style/Semicolon` when a semicolon at the beginning of a lambda block. ([@koic][])
diff --git a/lib/rubocop/cop/style/semicolon.rb b/lib/rubocop/cop/style/semicolon.rb
@@ -80,6 +80,7 @@ def tokens_for_lines
           processed_source.tokens.group_by(&:line)
         end
 
+        # rubocop:disable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
         def semicolon_position(tokens)
           if tokens.last.semicolon?
             -1
@@ -90,10 +91,13 @@ def semicolon_position(tokens)
           elsif exist_semicolon_after_left_curly_brace?(tokens) ||
                 exist_semicolon_after_left_string_interpolation_brace?(tokens)
             2
+          elsif exist_semicolon_after_left_lambda_curly_brace?(tokens)
+            3
           elsif exist_semicolon_before_right_string_interpolation_brace?(tokens)
             -4
           end
         end
+        # rubocop:enable Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
 
         def exist_semicolon_before_right_curly_brace?(tokens)
           tokens[-2]&.right_curly_brace? && tokens[-3]&.semicolon?
@@ -103,6 +107,10 @@ def exist_semicolon_after_left_curly_brace?(tokens)
           tokens[1]&.left_curly_brace? && tokens[2]&.semicolon?
         end
 
+        def exist_semicolon_after_left_lambda_curly_brace?(tokens)
+          tokens[2]&.type == :tLAMBEG && tokens[3]&.semicolon?
+        end
+
         def exist_semicolon_before_right_string_interpolation_brace?(tokens)
           tokens[-3]&.type == :tSTRING_DEND && tokens[-4]&.semicolon?
         end

diff --git a/spec/rubocop/cop/style/semicolon_spec.rb b/spec/rubocop/cop/style/semicolon_spec.rb
@@ -119,6 +119,17 @@ module Foo; end
     RUBY
   end
 
+  it 'registers an offense for a semicolon at the beginning of a lambda block' do
+    expect_offense(<<~RUBY)
+      foo -> {; bar }
+              ^ Do not use semicolons to terminate expressions.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      foo -> { bar }
+    RUBY
+  end
+
   it 'registers an offense for a semicolon at the end of a block' do
     expect_offense(<<~RUBY)
       foo { bar; }