Links to document texts without "rdoc-ref:" prefix

While links to generated HTML from RDoc file needs to be prefixed
by "rdoc-ref:" currently, in case of explicit references this
seems just redundant.

Also GitHub RDoc support does not work with this prefix.

This patch lets links to such document texts (".rb", ".rdoc" and
".md" now) refer URLs generated by `RDoc::TopLevel#http_url`
without the prefix.

lib/rdoc/markup/to_html.rb

@@ -357,6 +357,10 @@ def gen_url url, text
        url =~ /\.(gif|png|jpg|jpeg|bmp)$/ then
       "<img src=\"#{url}\" />"
     else
+      if scheme != 'link' and /\.(?:rb|rdoc|md)\z/i =~ url
+        url = url.sub(%r%\A([./]*)(.*)\z%) { "#$1#{$2.tr('.', '_')}.html" }
+      end
+
       text = text.sub %r%^#{scheme}:/*%i, ''
       text = text.sub %r%^[*\^](\d+)$%,   '\1'
 

test/rdoc/test_rdoc_markup_to_html.rb

@@ -738,6 +738,27 @@ def test_gen_url_ssl_image_url
     assert_equal '<img src="https://example.com/image.png" />', @to.gen_url('https://example.com/image.png', 'ignored')
   end
 
+  def test_gen_url_rdoc_file
+    assert_equal '<a href="doc/example_rdoc.html">example</a>',
+                 @to.gen_url('doc/example.rdoc', 'example')
+    assert_equal '<a href="../ex_doc/example_rdoc.html">example</a>',
+                 @to.gen_url('../ex.doc/example.rdoc', 'example')
+  end
+
+  def test_gen_url_md_file
+    assert_equal '<a href="doc/example_md.html">example</a>',
+                 @to.gen_url('doc/example.md', 'example')
+    assert_equal '<a href="../ex_doc/example_md.html">example</a>',
+                 @to.gen_url('../ex.doc/example.md', 'example')
+  end
+
+  def test_gen_url_rb_file
+    assert_equal '<a href="doc/example_rb.html">example</a>',
+                 @to.gen_url('doc/example.rb', 'example')
+    assert_equal '<a href="../ex_doc/example_rb.html">example</a>',
+                 @to.gen_url('../ex.doc/example.rb', 'example')
+  end
+
   def test_handle_regexp_HYPERLINK_link
     target = RDoc::Markup::RegexpHandling.new 0, 'link:README.txt'