add rc trace"

tests/suite.cm

@@ -3449,4 +3449,62 @@ return {
         var result = extract(text, /hello/i)
         if (result[0] != "Hello") throw "extract regex case insensitive failed"
     },
+
+    // ============================================================================
+    // GC PATHOLOGICAL CASES
+    // ============================================================================
+
+    test_gc_cycle_object_self: function() {
+        var obj = {name: "root"}
+        obj.self = obj
+        if (obj.self != obj) throw "self cycle failed"
+    },
+
+    test_gc_cycle_array_self: function() {
+        var arr = []
+        push(arr, arr)
+        if (arr[0] != arr) throw "array self cycle failed"
+    },
+
+    test_gc_cycle_object_array_pair: function() {
+        var obj = {kind: "node"}
+        var arr = [obj]
+        obj.arr = arr
+        if (obj.arr[0] != obj) throw "object/array cycle failed"
+    },
+
+    test_gc_shared_references: function() {
+        var shared = {value: 42}
+        var a = {ref: shared}
+        var b = {ref: shared}
+        if (a.ref != shared || b.ref != shared) throw "shared reference failed"
+    },
+
+    test_gc_object_key_cycle: function() {
+        var k = {}
+        var v = {label: "value"}
+        var o = {}
+        o[k] = v
+        v.back = o
+        if (o[k].back != o) throw "object key cycle failed"
+    },
+
+    test_gc_object_text_key_mix: function() {
+        var obj = {}
+        var key = "alpha"
+        var inner = {token: "x"}
+        obj[key] = inner
+        obj["beta"] = [inner, obj]
+        if (obj.alpha.token != "x") throw "text key value failed"
+        if (obj.beta[1] != obj) throw "text key cycle failed"
+    },
+
+    test_gc_array_object_key_mix: function() {
+        var obj = {}
+        var arr = [obj]
+        obj[arr] = "anchor"
+        obj.self = obj
+        if (obj[arr] != "anchor") throw "array object key failed"
+        if (arr[0] != obj) throw "array object mix failed"
+    },
 }