Fix #229

_test/extra.txt

@@ -323,3 +323,45 @@ foo
 </li>
 </ul>
 //= = = = = = = = = = = = = = = = = = = = = = = =//
+
+21: Fenced code block within list can start with tab
+//- - - - - - - - -//
+- List
+
+    ```
+    A
+    	B
+    C
+    ```
+//- - - - - - - - -//
+<ul>
+<li>
+<p>List</p>
+<pre><code>A
+	B
+C
+</code></pre>
+</li>
+</ul>
+//= = = = = = = = = = = = = = = = = = = = = = = =//
+22: Indented code block within list can start with tab
+//- - - - - - - - -//
+- List
+
+      A
+      	B
+      C
+
+a
+//- - - - - - - - -//
+<ul>
+<li>
+<p>List</p>
+<pre><code>A
+	B
+C
+</code></pre>
+</li>
+</ul>
+<p>a</p>
+//= = = = = = = = = = = = = = = = = = = = = = = =//

parser/fcode_block.go

@@ -72,10 +72,6 @@ func (b *fencedCodeBlockParser) Continue(node ast.Node, reader text.Reader, pc C
 	line, segment := reader.PeekLine()
 	fdata := pc.Get(fencedCodeBlockInfoKey).(*fenceData)
 
-	// if code block line starts with a tab, keep a tab as it is.
-	if segment.Padding != 0 {
-		preserveLeadingTabInCodeBlock(&segment, reader, fdata.indent)
-	}
 	w, pos := util.IndentWidth(line, reader.LineOffset())
 	if w < 4 {
 		i := pos
@@ -94,6 +90,10 @@ func (b *fencedCodeBlockParser) Continue(node ast.Node, reader text.Reader, pc C
 	pos, padding := util.DedentPositionPadding(line, reader.LineOffset(), segment.Padding, fdata.indent)
 
 	seg := text.NewSegmentPadding(segment.Start+pos, segment.Stop, padding)
+	// if code block line starts with a tab, keep a tab as it is.
+	if padding != 0 {
+		preserveLeadingTabInCodeBlock(&seg, reader, fdata.indent)
+	}
 	node.Lines().Append(seg)
 	reader.AdvanceAndSetPadding(segment.Stop-segment.Start-pos-1, padding)
 	return Continue | NoChildren

testutil/testutil.go

@@ -277,8 +277,12 @@ func DiffPretty(v1, v2 []byte) []byte {
 			c = " "
 		}
 		for _, line := range diff.Lines {
+			if c != " " {
+				b.WriteString(fmt.Sprintf("%s | %s\n", c, util.VisualizeSpaces(line)))
+			} else {
 				b.WriteString(fmt.Sprintf("%s | %s\n", c, line))
 			}
 		}
+	}
 	return b.Bytes()
 }