Fix unused variable warning in no_result_var mode with EBNF operators

Author: ydah

lib/racc/grammarfileparser.rb

@@ -295,7 +295,7 @@ def _add_many_rule(prev)
       return target if target
       target = _gen_target_name("many", prev)
       @many_rule_registry[prev.to_s] = target
-      src = SourceText.new("result = val[1] ? val[1].unshift(val[0]) : val", @filename, @scanner.lineno + 1)
+      src = SourceText.new(_many_action_code, @filename, @scanner.lineno + 1)
       act = UserAction.source_text(src)
       @grammar.add Rule.new(target, [], act)
       @grammar.add Rule.new(target, [prev, target], act)
@@ -308,13 +308,25 @@ def _add_many1_rule(prev)
       return target if target
       target = _gen_target_name("many1", prev)
       @many1_rule_registry[prev.to_s] = target
-      src = SourceText.new("result = val[1] ? val[1].unshift(val[0]) : val", @filename, @scanner.lineno + 1)
+      src = SourceText.new(_many_action_code, @filename, @scanner.lineno + 1)
       act = UserAction.source_text(src)
       @grammar.add Rule.new(target, [prev], act)
       @grammar.add Rule.new(target, [prev, target], act)
       target
     end
 
+    def _action_code(expression)
+      @result.params.result_var? ? "result = #{expression}" : expression
+    end
+
+    def _many_action_code
+      _action_code("val[1] ? val[1].unshift(val[0]) : val")
+    end
+
+    def _group_action_code
+      _action_code("val")
+    end
+
     def _add_group_rule(enum)
       target = @grammar.intern("-temp-group", true)
       rules, _ = _add_rule_block(target, enum)
@@ -323,7 +335,7 @@ def _add_group_rule(enum)
       unless target = @group_rule_registry[target_name]
         target = @grammar.intern("-group@#{target_name}", true)
         @group_rule_registry[target_name] = target
-        src = SourceText.new("result = val", @filename, @scanner.lineno + 1)
+        src = SourceText.new(_group_action_code, @filename, @scanner.lineno + 1)
         act = UserAction.source_text(src)
         rules.each do |syms, sprec|
           rule = Rule.new(target, syms, act)

test/test_grammar_file_parser.rb

@@ -11,5 +11,115 @@ def test_parse
       parser = Racc::GrammarFileParser.new(debug_flags)
       parser.parse(File.read(file), File.basename(file))
     end
+
+    def parse_grammar(grammar_source)
+      debug_flags = Racc::DebugFlags.parse_option_string('')
+      parser = Racc::GrammarFileParser.new(debug_flags)
+      parser.parse(grammar_source, 'test.y')
+    end
+
+    def test_no_result_var_with_many_operator
+      grammar_source = <<~GRAMMAR
+        class TestParser
+        options no_result_var
+
+        rule
+          root
+            : 'a' 'b'*
+      GRAMMAR
+
+      result = parse_grammar(grammar_source)
+
+      assert_equal false, result.params.result_var?
+
+      actions = result.grammar.each_rule.filter_map { |rule| rule.action.source&.text }
+      actions.each do |action|
+        refute_match(/\Aresult\s*=/, action, "Action should not start with 'result =' when no_result_var is set")
+      end
+    end
+
+    def test_no_result_var_with_many1_operator
+      grammar_source = <<~GRAMMAR
+        class TestParser
+        options no_result_var
+
+        rule
+          root
+            : 'a' 'b'+
+      GRAMMAR
+
+      result = parse_grammar(grammar_source)
+
+      assert_equal false, result.params.result_var?
+
+      actions = result.grammar.each_rule.filter_map { |rule| rule.action.source&.text }
+      actions.each do |action|
+        refute_match(/\Aresult\s*=/, action, "Action should not start with 'result =' when no_result_var is set")
+      end
+    end
+
+    def test_no_result_var_with_group_operator
+      grammar_source = <<~GRAMMAR
+        class TestParser
+        options no_result_var
+
+        rule
+          root
+            : ('a' | 'b')
+      GRAMMAR
+
+      result = parse_grammar(grammar_source)
+
+      assert_equal false, result.params.result_var?
+
+      actions = result.grammar.each_rule.filter_map { |rule| rule.action.source&.text }
+      actions.each do |action|
+        refute_match(/\Aresult\s*=/, action, "Action should not start with 'result =' when no_result_var is set")
+      end
+    end
+
+    def test_result_var_with_many_operator
+      grammar_source = <<~GRAMMAR
+        class TestParser
+
+        rule
+          root
+            : 'a' 'b'*
+      GRAMMAR
+
+      result = parse_grammar(grammar_source)
+
+      assert_equal true, result.params.result_var?
+
+      actions = result.grammar.each_rule.filter_map { |rule| rule.action.source&.text }.reject(&:empty?)
+      assert actions.any? { |action| action.match?(/\Aresult\s*=/) }, "Action should start with 'result =' when result_var is enabled"
+    end
+
+    def test_no_result_var_no_warnings
+      grammar_file = Tempfile.new(['test_no_result_var', '.y'])
+      grammar_file.write(<<~GRAMMAR)
+        class TestParser
+        options no_result_var
+
+        rule
+          root
+            : 'a' 'b'*
+            | 'c' 'd'+
+            | ('e' | 'f')
+      GRAMMAR
+      grammar_file.close
+
+      output_file = Tempfile.new(['test_no_result_var', '.rb'])
+      output_file.close
+
+      system("ruby", "-I#{LIB_DIR}", "-S", RACC, "-o", output_file.path, grammar_file.path)
+      assert $?.success?, "racc command failed"
+
+      warnings = `ruby -W #{output_file.path} 2>&1`
+      assert_equal "", warnings, "Expected no warnings but got: #{warnings}"
+    ensure
+      grammar_file&.unlink
+      output_file&.unlink
+    end
   end
 end