Declare parameters uninitialized

rclcpp/src/rclcpp/node_interfaces/node_parameters.cpp

@@ -349,6 +349,19 @@ __declare_parameter_common(
     initial_value = &overrides_it->second;
   }
 
+  // If there is no initial value, then skip initialization
+  if (initial_value->get_type() == rclcpp::PARAMETER_NOT_SET) {
+    // descriptor type should be set
+    assert(parameter_descriptor.type != rclcpp::PARAMETER_NOT_SET);
+    // Add declared parameters to storage (without a value)
+    parameter_infos[name].descriptor.name = name;
+    parameter_infos[name].descriptor.type = parameter_descriptor.type;
+    parameters_out[name] = parameter_infos.at(name);
+    rcl_interfaces::msg::SetParametersResult result;
+    result.successful = true;
+    return result;
+  }
+
   // Check with the user's callback to see if the initial value can be set.
   std::vector<rclcpp::Parameter> parameter_wrappers {rclcpp::Parameter(name, *initial_value)};
   // This function also takes care of default vs initial value.
@@ -413,14 +426,6 @@ declare_parameter_helper(
     parameter_descriptor.type = static_cast<uint8_t>(type);
   }
 
-  if (
-    rclcpp::PARAMETER_NOT_SET == default_value.get_type() &&
-    overrides.find(name) == overrides.end() &&
-    parameter_descriptor.dynamic_typing == false)
-  {
-    throw rclcpp::exceptions::NoParameterOverrideProvided(name);
-  }
-
   rcl_interfaces::msg::ParameterEvent parameter_event;
   auto result = __declare_parameter_common(
     name,

rclcpp/test/rclcpp/test_node.cpp

@@ -334,11 +334,17 @@ TEST_F(TestNode, declare_parameter_with_no_initial_values) {
   {
     rcl_interfaces::msg::ParameterDescriptor descriptor;
     descriptor.dynamic_typing = true;
-    // no default, no initial
+    // no default, no initial, dynamic typing
     rclcpp::ParameterValue value = node->declare_parameter(
       "parameter"_unq, rclcpp::ParameterValue{}, descriptor);
     EXPECT_EQ(value.get_type(), rclcpp::PARAMETER_NOT_SET);
   }
+  {
+    // no default, no initial, static typing
+    rclcpp::ParameterValue value = node->declare_parameter(
+      "parameter"_unq, rclcpp::ParameterType::PARAMETER_INTEGER);
+    EXPECT_EQ(value.get_type(), rclcpp::PARAMETER_NOT_SET);
+  }
   {
     // int default, no initial
     rclcpp::ParameterValue default_value(42);
@@ -2798,9 +2804,8 @@ TEST_F(TestNode, static_and_dynamic_typing) {
     EXPECT_EQ("hello!", param);
   }
   {
-    EXPECT_THROW(
-      node->declare_parameter("integer_override_not_given", rclcpp::PARAMETER_INTEGER),
-      rclcpp::exceptions::NoParameterOverrideProvided);
+    auto param = node->declare_parameter("integer_override_not_given", rclcpp::PARAMETER_INTEGER);
+    EXPECT_EQ(rclcpp::PARAMETER_NOT_SET, param.get_type());
   }
   {
     EXPECT_THROW(