hugolib, output: Handle aliases for all HTML formats

output/outputFormat.go

@@ -29,6 +29,7 @@ var (
 		BaseName:  "index",
 		Path:      "amp",
 		Rel:       "amphtml",
+		IsHTML:    true,
 	}
 
 	CalendarType = Format{
@@ -52,6 +53,7 @@ var (
 		MediaType: media.HTMLType,
 		BaseName:  "index",
 		Rel:       "canonical",
+		IsHTML:    true,
 	}
 
 	JSONType = Format{
@@ -113,6 +115,10 @@ type Format struct {
 	// as template parser.
 	IsPlainText bool
 
+	// IsHTML returns whether this format is int the HTML family. This includes
+	// HTML, AMP etc. This is used to decide when to create alias redirects etc.
+	IsHTML bool
+
 	// Enable to ignore the global uglyURLs setting.
 	NoUgly bool
 }

output/outputFormat_test.go

@@ -26,18 +26,29 @@ func TestDefaultTypes(t *testing.T) {
 	require.Equal(t, "webcal://", CalendarType.Protocol)
 	require.Empty(t, CalendarType.Path)
 	require.True(t, CalendarType.IsPlainText)
+	require.False(t, CalendarType.IsHTML)
 
 	require.Equal(t, "HTML", HTMLType.Name)
 	require.Equal(t, media.HTMLType, HTMLType.MediaType)
 	require.Empty(t, HTMLType.Path)
 	require.Empty(t, HTMLType.Protocol) // Will inherit the BaseURL protocol.
 	require.False(t, HTMLType.IsPlainText)
+	require.True(t, HTMLType.IsHTML)
+
+	require.Equal(t, "AMP", AMPType.Name)
+	require.Equal(t, media.HTMLType, AMPType.MediaType)
+	require.Equal(t, "amp", AMPType.Path)
+	require.Empty(t, AMPType.Protocol) // Will inherit the BaseURL protocol.
+	require.False(t, AMPType.IsPlainText)
+	require.True(t, AMPType.IsHTML)
 
 	require.Equal(t, "RSS", RSSType.Name)
 	require.Equal(t, media.RSSType, RSSType.MediaType)
 	require.Empty(t, RSSType.Path)
 	require.False(t, RSSType.IsPlainText)
 	require.True(t, RSSType.NoUgly)
+	require.False(t, CalendarType.IsHTML)
+
 }
 
 func TestGetType(t *testing.T) {