Don't warn on top-level comments

[mtrmac]

Motivated by containers/image#2128 .

Run the tests with -v to see that there are no warnings.

[thaJeztah]

Run the tests with -v to see that there are no warnings.

We should probably have an option to set the output of those logs (both to allow consumers to decide if they want logging, but it would also allow tests to verify the behavior).

[thaJeztah]

Interestingly, it looks like blackfriday already has code to handle HTML comments, but doesn't assign a dedicated type to it;

go-md2man/vendor/github.com/russross/blackfriday/v2/block.go

Lines 421 to 439 in 8363f7d

	// HTML comment, lax form
	func (p *Markdown) htmlComment(data []byte, doRender bool) int {
	i := p.inlineHTMLComment(data)
	// needs to end with a blank line
	if j := p.isEmpty(data[i:]); j > 0 {
	size := i + j
	if doRender {
	// trim trailing newlines
	end := size
	for end > 0 && data[end-1] == '\n' {
	end--
	}
	block := p.addBlock(HTMLBlock, data[:end])
	finalizeHTMLBlock(block)
	}
	return size
	}
	return 0
	}

Mostly out of curiosity, I patched the vendor directory to see if it would work to assign a dedicated type for that, and it looks like that works, so perhaps I'll open a PR for that in blackfriday;

diff --git a/md2man/roff.go b/md2man/roff.go
index c238a78..cc786db 100644
--- a/md2man/roff.go
+++ b/md2man/roff.go
@@ -165,13 +165,8 @@ func (r *roffRenderer) RenderNode(w io.Writer, node *blackfriday.Node, entering
                return blackfriday.GoToNext
        case blackfriday.TableCell:
                r.handleTableCell(w, node, entering)
-       case blackfriday.HTMLSpan:
-               // ignore other HTML tags
-       case blackfriday.HTMLBlock:
-               if bytes.HasPrefix(node.Literal, []byte("<!--")) {
-                       break // ignore comments, no warning
-               }
-               fmt.Fprintln(os.Stderr, "WARNING: go-md2man does not handle node type "+node.Type.String())
+       case blackfriday.HTMLSpan, blackfriday.HTMLComment:
+               // ignore other HTML tags and comments
        default:
                fmt.Fprintln(os.Stderr, "WARNING: go-md2man does not handle node type "+node.Type.String())
        }
diff --git a/vendor/github.com/russross/blackfriday/v2/block.go b/vendor/github.com/russross/blackfriday/v2/block.go
index dcd61e6..59d6235 100644
--- a/vendor/github.com/russross/blackfriday/v2/block.go
+++ b/vendor/github.com/russross/blackfriday/v2/block.go
@@ -430,7 +430,7 @@ func (p *Markdown) htmlComment(data []byte, doRender bool) int {
                        for end > 0 && data[end-1] == '\n' {
                                end--
                        }
-                       block := p.addBlock(HTMLBlock, data[:end])
+                       block := p.addBlock(HTMLComment, data[:end])
                        finalizeHTMLBlock(block)
                }
                return size
diff --git a/vendor/github.com/russross/blackfriday/v2/node.go b/vendor/github.com/russross/blackfriday/v2/node.go
index 04e6050..299f54e 100644
--- a/vendor/github.com/russross/blackfriday/v2/node.go
+++ b/vendor/github.com/russross/blackfriday/v2/node.go
@@ -26,6 +26,7 @@ const (
        Image
        Text
        HTMLBlock
+       HTMLComment
        CodeBlock
        Softbreak
        Hardbreak
@@ -53,6 +54,7 @@ var nodeTypeNames = []string{
        Image:          "Image",
        Text:           "Text",
        HTMLBlock:      "HTMLBlock",
+       HTMLComment:    "HTMLComment",
        CodeBlock:      "CodeBlock",
        Softbreak:      "Softbreak",
        Hardbreak:      "Hardbreak",

[thaJeztah]

LGTM, thanks!

[thaJeztah]

@cpuguy83 PTAL

[thaJeztah]

• also opened Add HTMLComment node type russross/blackfriday#714

[cpuguy83]

I published v2.0.3 with this patch (and a few others).