Fix missing carriage return before .TE if last table cell is empty

This is an alternative to 1fc61ec, which
tried to address this same issue, but introduced a regression.

Before this, tables ending with an empty cell would miss a carriage return
before the table closing marker (.TE), causing the table to not be closed,
and rendering to be broken;

       ┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬─────────────────────┬─────────┐
       │Col1                                                                                                                                                                                          │ Co2                │ Col3    │
       ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼─────────────────────┼─────────┤
       │row one                                                                                                                                                                                       │                     │ row two │
       ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼─────────────────────┼─────────┤
       │                                                                                                                                                                                              │                     │         │
       ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼─────────────────────┼─────────┤
       │                                                                                                                                                                                              │                     │         │
       ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼─────

After this patch, tables ending with an empty cell get a carriage return added
before the closing marker:

       ┌────────┬──────┬──────┐
       │Col1    │ Col2 │ Col3 │
       ├────────┼──────┼──────┤
       │row one │      │      │
       ├────────┼──────┼──────┤
       │row two │ x    │      │
       └────────┴──────┴──────┘

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

md2man/roff.go

@@ -259,7 +259,7 @@ func (r *roffRenderer) handleItem(w io.Writer, node *blackfriday.Node, entering
 func (r *roffRenderer) handleTable(w io.Writer, node *blackfriday.Node, entering bool) {
 	if entering {
 		out(w, tableStart)
-		//call walker to count cells (and rows?) so format section can be produced
+		// call walker to count cells (and rows?) so format section can be produced
 		columns := countColumns(node)
 		out(w, strings.Repeat("l ", columns)+"\n")
 		out(w, strings.Repeat("l ", columns)+".\n")
@@ -283,9 +283,17 @@ func (r *roffRenderer) handleTableCell(w io.Writer, node *blackfriday.Node, ente
 			out(w, start)
 		}
 	} else {
-		// need to carriage return if we are at the end of the header row
-		if node.IsHeader && node.Next == nil {
-			end = end + crTag
+		if node.Next == nil {
+			if node.IsHeader {
+				// need to carriage return if we are at the end of the header row
+				end = end + crTag
+			} else if node.FirstChild == nil {
+				// empty cell: need to carriage return if we are at the end of
+				// the table, because handleText() will not be called if there's
+				// no text to preocess (which would otherwise add the trailing
+				// carriage return)
+				end = crTag
+			}
 		}
 		out(w, end)
 	}

md2man/roff_test.go

@@ -272,6 +272,29 @@ robin	red.
 	doTestsInlineParam(t, tests, TestParams{blackfriday.Tables})
 }
 
+func TestTableWithEmptyCell(t *testing.T) {
+	var tests = []string{
+		`
+| Col1     | Col2  | Col3 |
+|:---------|:-----:|:----:| 
+| row one  |       |      | 
+| row two  | x     |      |
+`,
+		`.nh
+
+.TS
+allbox;
+l l l 
+l l l .
+\fB\fCCol1\fR	\fB\fCCol2\fR	\fB\fCCol3\fR
+row one		
+row two	x	
+.TE
+`,
+	}
+	doTestsInlineParam(t, tests, TestParams{blackfriday.Tables})
+}
+
 func TestLinks(t *testing.T) {
 	var tests = []string{
 		"See [docs](https://docs.docker.com/) for\nmore",