Fix merge-key handling in case the dictionary contains a sub-dictionary

Author: nlescoua-bpk

src/nodebuilder.cpp

@@ -70,6 +70,7 @@ void NodeBuilder::OnMapStart(const Mark& mark, const std::string& tag,
   node.set_tag(tag);
   node.set_style(style);
   m_mapDepth++;
+  m_mergeDicts.emplace_back();
 }
 
 void MergeMapCollection(detail::node& map_to, detail::node& map_from,
@@ -86,11 +87,12 @@ void MergeMapCollection(detail::node& map_to, detail::node& map_from,
 void NodeBuilder::OnMapEnd() {
   assert(m_mapDepth > 0);
   detail::node& collection = *m_stack.back();
-  for (detail::node* n : m_mergeDicts) {
+  auto& toMerge = *m_mergeDicts.rbegin();
+  for (detail::node* n : toMerge) {
     MergeMapCollection(collection, *n, m_pMemory);
   }
-  m_mergeDicts.clear();
   m_mapDepth--;
+  m_mergeDicts.pop_back();
   Pop();
 }
 
@@ -135,13 +137,13 @@ void NodeBuilder::Pop() {
           ((nk.tag() == "tag:yaml.org,2002:merge" && nk.scalar() == "<<") ||
            (nk.tag() == "?" && nk.scalar() == "<<"))) {
         if (node.type() == NodeType::Map) {
-          m_mergeDicts.emplace_back(&node);
+          m_mergeDicts.rbegin()->emplace_back(&node);
           m_keys.pop_back();
         } else if (node.type() == NodeType::Sequence) {
           for (auto i = node.begin(); i != node.end(); i++) {
             auto v = *i;
             if ((*v).type() == NodeType::Map) {
-              m_mergeDicts.emplace_back(&(*v));
+              m_mergeDicts.rbegin()->emplace_back(&(*v));
             } else {
               throw ParserException(
                   node.mark(),

src/nodebuilder.h

@@ -67,7 +67,7 @@ class NodeBuilder : public EventHandler {
 
   using PushedKey = std::pair<detail::node*, bool>;
   std::vector<PushedKey> m_keys;
-  Nodes m_mergeDicts;
+  std::vector<Nodes> m_mergeDicts;
   std::size_t m_mapDepth;
 };
 }  // namespace YAML

test/integration/load_node_test.cpp

@@ -188,7 +188,7 @@ TEST(LoadNodeTest, MergeKeyB) {
   Node node = Load(
       "{x: &foo {a : 1,b : 1,c : 1}, y: &bar {d: 2, e : 2, f : 2, a : 2}, z: "
       "&stuff { << : *foo, b : 3}, w: { << : [*stuff, *bar], c: 4 }, v: { '<<' "
-      ": *foo } , u : {!!merge << : *bar} }");
+      ": *foo } , u : {!!merge << : *bar}, t: {!!merge << : *bar, h: 3} }");
   EXPECT_EQ(NodeType::Map, node["z"].Type());
   EXPECT_EQ(NodeType::Map, node["w"].Type());
   EXPECT_FALSE(node["z"]["<<"]);
@@ -208,6 +208,10 @@ TEST(LoadNodeTest, MergeKeyB) {
 
   EXPECT_FALSE(node["u"]["<<"]);
   EXPECT_EQ(2, node["u"]["d"].as<int>());
+
+  EXPECT_FALSE(node["t"]["<<"]);
+  EXPECT_EQ(2, node["t"]["d"].as<int>());
+  EXPECT_EQ(3, node["t"]["h"].as<int>());
 }
 
 TEST(LoadNodeTest, ForceInsertIntoMap) {