Throw an error when shortcode is expected to be closed

Fixes #10675

hugolib/shortcode.go

@@ -224,6 +224,10 @@ func (s shortcode) insertPlaceholder() bool {
 	return !s.doMarkup || s.configVersion() == 1
 }
 
+func (s shortcode) needsInner() bool {
+	return s.info != nil && s.info.ParseInfo().IsInner
+}
+
 func (s shortcode) configVersion() int {
 	if s.info == nil {
 		// Not set for inline shortcodes.
@@ -557,6 +561,7 @@ func (s *shortcodeHandler) extractShortcode(ordinal, level int, source []byte, p
 	cnt := 0
 	nestedOrdinal := 0
 	nextLevel := level + 1
+	closed := false
 	const errorPrefix = "failed to extract shortcode"
 
 	fail := func(err error, i pageparser.Item) error {
@@ -612,9 +617,10 @@ Loop:
 			}
 
 		case currItem.IsShortcodeClose():
+			closed = true
 			next := pt.Peek()
 			if !sc.isInline {
-				if sc.info == nil || !sc.info.ParseInfo().IsInner {
+				if !sc.needsInner() {
 					if next.IsError() {
 						// return that error, more specific
 						continue
@@ -689,6 +695,11 @@ Loop:
 				}
 			}
 		case currItem.IsDone():
+			if !currItem.IsError() {
+				if !closed && sc.needsInner() {
+					return sc, fmt.Errorf("%s: unclosed shortcode %q", errorPrefix, sc.name)
+				}
+			}
 			// handled by caller
 			pt.Backup()
 			break Loop

hugolib/shortcode_test.go

@@ -1241,3 +1241,38 @@ InnerDeindent: closing-no-newline: 0
 
 `)
 }
+
+// Issue 10675.
+func TestShortcodeErrorWhenItShouldBeClosed(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- config.toml --
+disableKinds = ["home", "taxonomy", "term"]
+-- content/p1.md --
+---
+title: "p1"
+---
+
+{{< sc >}}
+
+Text.
+
+-- layouts/shortcodes/sc.html --
+Inner: {{ .Get 0 }}: {{ len .Inner }}
+-- layouts/_default/single.html --
+{{ .Content }}
+`
+
+	b, err := NewIntegrationTestBuilder(
+		IntegrationTestConfig{
+			T:           t,
+			TxtarString: files,
+			Running:     true,
+			Verbose:     true,
+		},
+	).BuildE()
+
+	b.Assert(err, qt.Not(qt.IsNil))
+	b.Assert(err.Error(), qt.Contains, `p1.md:5:1": failed to extract shortcode: unclosed shortcode "sc"`)
+}