Do not parse non-Ruby files as Ruby when :markup: is markdown or tomdoc

lib/rdoc/parser.rb

@@ -170,7 +170,7 @@ def self.for(top_level, content, options, stats)
     file_name = top_level.absolute_name
     return if binary? file_name
 
-    parser = use_markup content
+    parser = use_markup content, file_name
 
     unless parser then
       parse_name = file_name
@@ -228,14 +228,24 @@ def self.remove_modeline(content)
   # appear on the second or third line.
   #
   # Any comment style may be used to hide the markup comment.
+  #
+  # The +tomdoc+ and +markdown+ markups name comment formats rather than
+  # parsers, so they select the Ruby parser only when the given +file_name+
+  # is a Ruby file (or when no +file_name+ is given).
 
-  def self.use_markup(content)
+  def self.use_markup(content, file_name = nil)
     markup = content.lines.first(3).grep(/markup:\s+(\w+)/) { $1 }.first
 
     return unless markup
 
-    # TODO Ruby should be returned only when the filename is correct
-    return RDoc::Parser::Ruby if %w[tomdoc markdown].include? markup
+    # tomdoc and markdown are comment formats, not parsers, so they imply
+    # the Ruby parser only when the file name does not select another parser
+    if %w[tomdoc markdown].include? markup then
+      return RDoc::Parser::Ruby if file_name.nil? or
+        can_parse_by_name(file_name) == RDoc::Parser::Ruby
+
+      return
+    end
 
     markup = Regexp.escape markup
 

test/rdoc/parser/parser_test.rb

@@ -227,6 +227,28 @@ def test_class_for_markup
     end
   end
 
+  def test_class_for_markup_markdown_c_file
+    content = <<-CONTENT
+/* file.c */
+/* :markup: markdown */
+
+/* method comment */
+VALUE rb_a_foo(VALUE self) {
+}
+    CONTENT
+
+    file_name = File.join Dir.tmpdir, "file.c"
+    File.write file_name, content
+
+    top_level = @store.add_file file_name
+
+    parser = @RP.for top_level, content, @options, :stats
+
+    assert_kind_of @RP::C, parser
+  ensure
+    File.unlink file_name
+  end
+
   def test_class_use_markup
     content = <<-CONTENT
 # coding: utf-8 markup: rd
@@ -247,6 +269,15 @@ def test_class_use_markup_markdown
     assert_equal @RP::Ruby, parser
   end
 
+  def test_class_use_markup_markdown_file_name
+    content = <<-CONTENT
+# coding: utf-8 markup: markdown
+    CONTENT
+
+    assert_equal @RP::Ruby, @RP.use_markup(content, 'file.rb')
+    assert_nil @RP.use_markup(content, 'file.c')
+  end
+
   def test_class_use_markup_modeline
     content = <<-CONTENT
 # -*- coding: utf-8 -*-
@@ -292,6 +323,15 @@ def test_class_use_markup_tomdoc
     assert_equal @RP::Ruby, parser
   end
 
+  def test_class_use_markup_tomdoc_file_name
+    content = <<-CONTENT
+# coding: utf-8 markup: tomdoc
+    CONTENT
+
+    assert_equal @RP::Ruby, @RP.use_markup(content, 'file.rb')
+    assert_nil @RP.use_markup(content, 'file.c')
+  end
+
   def test_class_use_markup_none
     parser = @RP.use_markup ''