Prevent cyclic ref crash in JSON encode

Note that this commit makes no promise about great JSON output from the encoder, but the cyclic refs should be broken.

Fixes #1123

hugolib/node.go

@@ -22,7 +22,7 @@ import (
 
 type Node struct {
 	RSSLink template.HTML
-	Site    *SiteInfo
+	Site    *SiteInfo `json:"-"`
 	//	layout      string
 	Data        map[string]interface{}
 	Title       string

hugolib/page.go

@@ -71,7 +71,7 @@ type Page struct {
 	renderingConfigInit sync.Once
 	PageMeta
 	Source
-	Position
+	Position `json:"-"`
 	Node
 	pageMenus     PageMenus
 	pageMenusInit sync.Once

hugolib/site.go

@@ -79,7 +79,7 @@ type Site struct {
 	timer          *nitro.B
 	Targets        targetList
 	targetListInit sync.Once
-	Completed      chan bool
+	Completed      chan bool `json:"-"`
 	RunMode        runmode
 	params         map[string]interface{}
 	draftCount     int

hugolib/siteJSONEncode_test.go

@@ -0,0 +1,32 @@
+package hugolib
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+)
+
+// Issue #1123
+// Testing prevention of cyclic refs in JSON encoding
+// May be smart to run with: -timeout 4000ms
+func TestEncodePage(t *testing.T) {
+
+	// borrowed from menu_test.go
+	s := createTestSite(MENU_PAGE_SOURCES)
+	testSiteSetup(s, t)
+
+	j, err := json.Marshal(s)
+	check(t, err)
+	fmt.Println("Site as JSON", string(j))
+
+	p, err := json.Marshal(s.Pages[0])
+	check(t, err)
+	fmt.Println("Page as JSON", string(p))
+
+}
+
+func check(t *testing.T, err error) {
+	if err != nil {
+		t.Fatalf("Failed %s", err)
+	}
+}