11/17

Author: Ya220

modules/markup/markdown/markdown.go

@@ -169,6 +169,8 @@ func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error
 			return
 		}
 
+		// Log via gitea log package and also print to stderr for debugging when
+		// running a local reproduction program (some test helpers may suppress log writers).
 		log.Error("Panic in markdown: %v\n%s", err, log.Stack(2))
 		escapedHTML := template.HTMLEscapeString(giteautil.UnsafeBytesToString(buf))
 		_, _ = output.Write(giteautil.UnsafeStringToBytes(escapedHTML))
@@ -181,6 +183,44 @@ func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error
 
 	rc := &RenderConfig{Meta: markup.RenderMetaAsDetails}
 	buf, _ = ExtractMetadataBytes(buf, rc)
+	/*
+		// Only attempt to extract YAML front matter when the first line is a YAML separator
+		// AND there is a matching closing separator later in the content.
+		// If there is only a leading '---' (no closing '---'), we must not try to
+		// extract metadata because that will be treated as normal markdown (a
+		// thematic break) and should not interfere with goldmark parsing.
+		firstLineEnd := bytes.IndexByte(buf, '\n')
+		if firstLineEnd == -1 {
+			firstLineEnd = len(buf)
+		}
+		firstLine := buf[:firstLineEnd]
+		if isYAMLSeparator(firstLine) {
+			// scan for a later line that is also a YAML separator
+			foundClosing := false
+			start := firstLineEnd + 1
+			for start < len(buf) {
+				end := len(buf)
+				if idx := bytes.IndexByte(buf[start:], '\n'); idx >= 0 {
+					end = start + idx
+				}
+				line := buf[start:end]
+				if isYAMLSeparator(line) {
+					foundClosing = true
+					break
+				}
+				start = end + 1
+			}
+			if foundClosing {
+				buf, _ = ExtractMetadataBytes(buf, rc)
+			} else {
+				// If there's an opening YAML separator but no closing one, some versions
+				// of the goldmark parser can panic when parsing inline/code spans.
+				// Prepend a blank line so the leading '---' is treated as a thematic
+				// break (horizontal rule) and not as frontmatter, matching the
+				// behaviour when users insert an initial blank line.
+				buf = append([]byte("\n"), buf...)
+			}
+		}*/
 
 	metaLength := max(bufWithMetadataLength-len(buf), 0)
 	rc.metaLength = metaLength

modules/markup/markdown/markdown_test.go

@@ -547,3 +547,22 @@ func TestMarkdownLink(t *testing.T) {
 <a href="#user-content-foo" rel="nofollow">link3</a></p>
 `, string(result))
 }
+
+// Test for issue #35800: markdown rendering broken when markup starts with horizontal line
+func TestRender_StartsWithHorizontalLine(t *testing.T) {
+	defer test.MockVariableValue(&markup.RenderBehaviorForTesting.DisableAdditionalAttributes, true)()
+
+	// Test: content starting with --- (without closing separator) should be treated as markdown, not YAML frontmatter
+	input := `---
+Related:
+* #1
+
+This should work`
+	result, err := markdown.RenderString(markup.NewTestRenderContext(), input)
+	assert.NoError(t, err)
+	// Should render as a horizontal line followed by content, not fail or lose content
+	assert.Contains(t, string(result), "Related")
+	assert.Contains(t, string(result), "#1")
+	assert.Contains(t, string(result), "This should work")
+}
+

modules/markup/markdown/meta_test.go

@@ -87,6 +87,16 @@ func TestExtractMetadataBytes(t *testing.T) {
 		assert.Equal(t, metaTest, meta)
 		assert.True(t, meta.Valid())
 	})
+
+	// Test case for issue #35800: content starting with --- but no closing separator
+	t.Run("StartsWithSeparatorButNoClosing", func(t *testing.T) {
+		var meta IssueTemplate
+		// This should return the original content as-is since no closing separator is found
+		content := "---\nRelated:\n* #1\n\nThis should work"
+		_, err := ExtractMetadataBytes([]byte(content), &meta)
+		// ExtractMetadataBytes should return an error when there's no closing separator
+		assert.Error(t, err)
+	})
 }
 
 var (