hugolib, output: Restrict Render to regular Pages

Using it for list pages doesn't work and has potential weird side-effects.

The user probably meant to range over .Site.ReqularPages, and that is now marked clearly in the log.

2 files changed, 17 insertions, 7 deletions

diff --git a/output/layout.go b/output/layout.go
index cda6eb8a0..a2bfd7717 100644
--- a/output/layout.go
+++ b/output/layout.go
@@ -83,19 +83,23 @@ indexes/indexes.NAME.SUFFIX indexes/indexes.SUFFIX
 `
 )
 
-func (l *LayoutHandler) For(d LayoutDescriptor, layoutOverride string, f Format) []string {
+func (l *LayoutHandler) For(d LayoutDescriptor, layoutOverride string, f Format) ([]string, error) {
 
 	// We will get lots of requests for the same layouts, so avoid recalculations.
 	key := layoutCacheKey{d, layoutOverride, f}
 	l.mu.RLock()
 	if cacheVal, found := l.cache[key]; found {
 		l.mu.RUnlock()
-		return cacheVal
+		return cacheVal, nil
 	}
 	l.mu.RUnlock()
 
 	var layouts []string
 
+	if layoutOverride != "" && d.Kind != "page" {
+		return layouts, fmt.Errorf("Custom layout (%q) only supported for regular pages, not kind %q", layoutOverride, d.Kind)
+	}
+
 	layout := d.Layout
 
 	if layoutOverride != "" {
@@ -106,7 +110,7 @@ func (l *LayoutHandler) For(d LayoutDescriptor, layoutOverride string, f Format)
 
 	if d.Kind == "page" {
 		if isRSS {
-			return []string{}
+			return []string{}, nil
 		}
 		layouts = regularPageLayouts(d.Type, layout, f)
 	} else {
@@ -148,14 +152,14 @@ func (l *LayoutHandler) For(d LayoutDescriptor, layoutOverride string, f Format)
 			}
 		}
 
-		return layoutsWithThemeLayouts
+		return layoutsWithThemeLayouts, nil
 	}
 
 	l.mu.Lock()
 	l.cache[key] = layouts
 	l.mu.Unlock()
 
-	return layouts
+	return layouts, nil
 }
 
 func resolveListTemplate(d LayoutDescriptor, f Format,
diff --git a/output/layout_test.go b/output/layout_test.go
index b38bd9c13..e59a16fcb 100644
--- a/output/layout_test.go
+++ b/output/layout_test.go
@@ -68,8 +68,9 @@ func TestLayout(t *testing.T) {
 		t.Run(this.name, func(t *testing.T) {
 			l := NewLayoutHandler(this.hasTheme)
 
-			layouts := l.For(this.d, this.layoutOverride, this.tp)
+			layouts, err := l.For(this.d, this.layoutOverride, this.tp)
 
+			require.NoError(t, err)
 			require.NotNil(t, layouts)
 			require.True(t, len(layouts) >= len(this.expect))
 			// Not checking the complete list for now ...
@@ -83,6 +84,10 @@ func TestLayout(t *testing.T) {
 		})
 	}
 
+	l := NewLayoutHandler(false)
+	_, err := l.For(LayoutDescriptor{Kind: "taxonomyTerm", Section: "tag"}, "override", RSSFormat)
+	require.Error(t, err)
+
 }
 
 func BenchmarkLayout(b *testing.B) {
@@ -90,7 +95,8 @@ func BenchmarkLayout(b *testing.B) {
 	l := NewLayoutHandler(false)
 
 	for i := 0; i < b.N; i++ {
-		layouts := l.For(descriptor, "", HTMLFormat)
+		layouts, err := l.For(descriptor, "", HTMLFormat)
+		require.NoError(b, err)
 		require.NotEmpty(b, layouts)
 	}
 }