[poincare] TreeHandle: the constructor from a identifier retains the

node if it has one

poincare/include/poincare/expression.h

@@ -248,6 +248,7 @@ public:
 protected:
   static bool SimplificationHasBeenInterrupted();
   Expression(const ExpressionNode * n) : TreeHandle(n) {}
+  Expression(int nodeIdentifier) : TreeHandle(nodeIdentifier) {}
   template<typename U>
   static Expression UntypedBuilderOneChild(Expression children) {
     assert(children.type() == ExpressionNode::Type::Matrix);
@@ -284,7 +285,6 @@ protected:
   }
 
   /* Hierarchy */
-  Expression(int nodeIdentifier) : TreeHandle(nodeIdentifier) {}
   Expression parent() const; // TODO try to inline
   void defaultSetChildrenInPlace(Expression other);
   void addChildAtIndexInPlace(TreeHandle t, int index, int currentNumberOfChildren) = delete;

poincare/include/poincare/tree_handle.h

@@ -103,7 +103,11 @@ public:
 protected:
   /* Constructor */
   TreeHandle(const TreeNode * node);
-  TreeHandle(int nodeIndentifier = TreeNode::NoNodeIdentifier) : m_identifier(nodeIndentifier) {}
+  TreeHandle(int nodeIndentifier = TreeNode::NoNodeIdentifier) : m_identifier(nodeIndentifier) {
+    if (hasNode(nodeIndentifier)) {
+      node()->retain();
+    }
+  }
   // WARNING: if the children table is the result of a cast, the object downcasted has to be the same size as a TreeHandle.
   static TreeHandle BuildWithBasicChildren(TreeNode * node, TreeHandle * children = nullptr, int numberOfChildren = 0);
 

poincare/src/integer.cpp

@@ -107,9 +107,7 @@ Integer::Integer(native_uint_t * digits, uint16_t numberOfDigits, bool negative)
   TreeHandle h = TreeHandle::BuildWithBasicChildren(node);
   /* Integer is a TreeHandle that keeps an extra integer. We cannot just cast
    * the TreeHandle in Integer, we have to build a new Integer. To do so, we
-   * pilfer the TreeHandle identifier. We thus have to increment the node
-   * reference counter to prevent its destruction when we leave this scope. */
-  node->retain();
+   * pilfer the TreeHandle identifier. */
   new (this) Integer(h.identifier(), negative);
 }