Respect markup comment in non-ruby files

Fixes #1597

Author: Earlopain

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
@@ -229,21 +229,22 @@ def self.remove_modeline(content)
   #
   # Any comment style may be used to hide the markup comment.
 
-  def self.use_markup(content)
+  def self.use_markup(content, file_path)
     markup = content.lines.first(3).grep(/markup:\s+(\w+)/) { $1 }.first
 
-    return unless markup
+    if markup
+      return RDoc::Parser::Ruby if markup == "tomdoc"
 
-    # TODO Ruby should be returned only when the filename is correct
-    return RDoc::Parser::Ruby if %w[tomdoc markdown].include? markup
-
-    markup = Regexp.escape markup
-
-    _, selected = RDoc::Parser.parsers.find do |_, parser|
-      /^#{markup}$/i =~ parser.name.sub(/.*:/, '')
+      markup = Regexp.escape markup
+      _, selected = RDoc::Parser.parsers.find do |_, parser|
+        /^#{markup}$/i =~ parser.name.sub(/.*:/, '')
+      end
+      selected
+    else
+      selected = RDoc::Parser.can_parse_by_name(file_path)
+      return if selected == RDoc::Parser::Simple
+      selected
     end
-
-    selected
   end
 
   ##

test/rdoc/parser/parser_test.rb

@@ -232,7 +232,7 @@ def test_class_use_markup
 # coding: utf-8 markup: rd
     CONTENT
 
-    parser = @RP.use_markup content
+    parser = @RP.use_markup content, ""
 
     assert_equal @RP::RD, parser
   end
@@ -242,9 +242,9 @@ def test_class_use_markup_markdown
 # coding: utf-8 markup: markdown
     CONTENT
 
-    parser = @RP.use_markup content
+    parser = @RP.use_markup content, ""
 
-    assert_equal @RP::Ruby, parser
+    assert_equal @RP::Markdown, parser
   end
 
   def test_class_use_markup_modeline
@@ -253,7 +253,7 @@ def test_class_use_markup_modeline
 # markup: rd
     CONTENT
 
-    parser = @RP.use_markup content
+    parser = @RP.use_markup content, ""
 
     assert_equal @RP::RD, parser
   end
@@ -266,7 +266,7 @@ def test_class_use_markup_modeline_shebang
  */
     CONTENT
 
-    parser = @RP.use_markup content
+    parser = @RP.use_markup content, ""
 
     assert_equal @RP::RD, parser
   end
@@ -277,7 +277,7 @@ def test_class_use_markup_shebang
 # coding: utf-8 markup: rd
     CONTENT
 
-    parser = @RP.use_markup content
+    parser = @RP.use_markup content, ""
 
     assert_equal @RP::RD, parser
   end
@@ -287,13 +287,13 @@ def test_class_use_markup_tomdoc
 # coding: utf-8 markup: tomdoc
     CONTENT
 
-    parser = @RP.use_markup content
+    parser = @RP.use_markup content, ""
 
     assert_equal @RP::Ruby, parser
   end
 
   def test_class_use_markup_none
-    parser = @RP.use_markup ''
+    parser = @RP.use_markup '', ''
 
     assert_nil parser
   end
@@ -303,11 +303,25 @@ def test_class_use_markup_unknown
 # :markup: RDoc
     CONTENT
 
-    parser = @RP.use_markup content
+    parser = @RP.use_markup content, ""
 
     assert_nil parser
   end
 
+  def test_class_use_markup_filepath
+    parser = @RP.use_markup "", "foo.rb"
+
+    assert_equal @RP::Ruby, parser
+  end
+
+  def test_class_use_markup_content_and_filepath
+    parser = @RP.use_markup <<~C, "foo.c"
+      /* :markup: markdown */
+    C
+
+    assert_equal @RP::Markdown, parser
+  end
+
   def test_initialize
     with_top_level("file.rb", "") do |top_level, content|
       @RP.new top_level, content, @options, nil