improve rendering of automatic links

Do not render the URL of automatic links twice.

Signed-off-by: Ruben Jenster <r.jenster@drachenfels.de>

md2man/roff.go

@@ -1,6 +1,7 @@
 package md2man
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"os"
@@ -109,11 +110,16 @@ func (r *roffRenderer) RenderNode(w io.Writer, node *blackfriday.Node, entering
 			out(w, strongCloseTag)
 		}
 	case blackfriday.Link:
-		if !entering {
-			// Hyphens in a link must be escaped to avoid word-wrap in the rendered man page.
-			escapedLink := strings.ReplaceAll(string(node.LinkData.Destination), "-", "\\-")
-			out(w, linkTag+escapedLink+linkCloseTag)
+		// Don't render the link text for automatic links, because this
+		// will only duplicate the URL in the roff output.
+		// See https://daringfireball.net/projects/markdown/syntax#autolink
+		if !bytes.Equal(node.LinkData.Destination, node.FirstChild.Literal) {
+			out(w, string(node.FirstChild.Literal))
 		}
+		// Hyphens in a link must be escaped to avoid word-wrap in the rendered man page.
+		escapedLink := strings.ReplaceAll(string(node.LinkData.Destination), "-", "\\-")
+		out(w, linkTag+escapedLink+linkCloseTag)
+		walkAction = blackfriday.SkipChildren
 	case blackfriday.Image:
 		// ignore images
 		walkAction = blackfriday.SkipChildren

md2man/roff_test.go

@@ -338,6 +338,8 @@ func TestLinks(t *testing.T) {
 		".nh\n\n.PP\nSee docs\n\\[la]https://docs.docker.com/\\[ra] for\nmore\n",
 		"See [docs](https://docs-foo.docker.com/) for\nmore",
 		".nh\n\n.PP\nSee docs\n\\[la]https://docs\\-foo.docker.com/\\[ra] for\nmore\n",
+		"See <https://docs-foo.docker.com/> for\nmore",
+		".nh\n\n.PP\nSee \n\\[la]https://docs\\-foo.docker.com/\\[ra] for\nmore\n",
 	}
 	doTestsInline(t, tests)
 }