Garbage-collect dictionaries properly

src/arena.cpp

@@ -146,7 +146,7 @@ Result<PodObject*> Arena::gc_pair(PodPair* obj) {
 }
 
 Result<PodObject*> Arena::gc_array(PodArray* obj) {
-  auto nobj = TRY(alloc<PodArray>(obj->size));
+  auto nobj = TRY(alloc<PodArray>(sizeof(OffPtr<PodObject>) * obj->size));
   nobj->header.tag = Tag::Array;
   nobj->size = obj->size;
   for (uint64_t i = 0; i < obj->size; i++) {
@@ -165,5 +165,13 @@ Result<PodObject*> Arena::gc_bytearray(PodByteArray* obj) {
 }
 
 Result<PodObject*> Arena::gc_dict(PodDict* obj) {
-  return ErrorCode::NotImplemented;
+  auto nobj = TRY(alloc<PodDict>(obj->size * 2 * sizeof(OffPtr<PodObject>)));
+  nobj->header.tag = Tag::Dict;
+  nobj->size = obj->size;
+  for (uint64_t i = 0; i < obj->size * 2; i++) {
+    PodObject* val = obj->data[i].get(obj);
+    nobj->data[i] = OffPtr<PodObject>(nobj, TRY(gc_pod(val)));
+  }
+  return nobj;
+  // return ErrorCode::NotImplemented;
 }

src/common.cpp

@@ -216,6 +216,7 @@ Result<Dict> Dict::insert(Arena& arena, Value& key, Value& value) {
   }
 
   auto pod = TRY(arena.alloc<PodDict>(2 * s * sizeof(OffPtr<PodObject>)));
+  pod->header.tag = Tag::Dict;
   pod->size = s;
 
   auto vpod = _value.get();

test/dict.cpp

@@ -15,7 +15,11 @@ TEST_CASE(dict_insert) {
   d = DIEX(d.insert(arena, 0, 5));
   d = DIEX(d.insert(arena, 2, 6));
 
+  DIEX(arena.gc());
+
   auto s = DIEX(write_one(arena, d));
 
+  DIEX(arena.gc());
+
   ASSERT_EQUALS(s, "{0 5 1 3 2 6 3 3}");
 }