Skip namespace forward-declared classes

Author: cfis

lib/ruby-bindgen/generators/rice/rice.rb

@@ -395,6 +395,17 @@ def visit_constructor(cursor)
       # constants, embedded types, and any auto-generated template bases needed
       # before the class itself can be registered.
       def visit_class_decl(cursor)
+        # Namespace-scope forward-declared C++ classes are often completed in a
+        # different header. Emitting a Rice class here creates a Ruby constant
+        # with no superclass, and a later complete definition then conflicts.
+        # Keep nested incomplete classes on the existing special path, and keep
+        # opaque structs available for handle-style APIs.
+        if cursor.kind == :cursor_class_decl &&
+           cursor.opaque_declaration? &&
+           ![:cursor_class_decl, :cursor_struct].include?(cursor.semantic_parent.kind)
+          return
+        end
+
         # Skip explicitly listed symbols
         return if skip_symbol?(cursor)
 

test/headers/cpp/forward_declared_all_layers.hpp

@@ -0,0 +1,15 @@
+#include "forward_declared_classes.hpp"
+
+namespace ForwardDeclaredClasses
+{
+  class ActivationLayer : public Layer
+  {
+  public:
+    ActivationLayer() = default;
+
+    bool forward() const
+    {
+      return true;
+    }
+  };
+}

test/headers/cpp/forward_declared_classes.hpp

@@ -0,0 +1,21 @@
+namespace ForwardDeclaredClasses
+{
+  class ActivationLayer;
+
+  class Layer
+  {
+  public:
+    virtual ~Layer() = default;
+
+    bool enabled() const
+    {
+      return true;
+    }
+  };
+
+  class Net
+  {
+  public:
+    void setActivation(ActivationLayer* layer);
+  };
+}

test/rice_generator_test.rb

@@ -175,4 +175,25 @@ class FunctionTemplate
     assert_includes rendered, "Rice::Data_Type<Tests::FunctionTemplate<&Tests::callback_ints>>"
     assert_includes rendered, "FunctionTemplate_instantiate<&Tests::callback_ints>"
   end
+
+  def test_namespace_scope_forward_declared_classes_do_not_generate_bindings
+    config_dir = File.join(__dir__, "headers", "cpp")
+    config = load_config(config_dir)
+    inputter = RubyBindgen::Inputter.new(config_dir, ["forward_declared_classes.hpp",
+                                                      "forward_declared_all_layers.hpp"])
+    outputter = create_outputter("cpp")
+    generator = RubyBindgen::Generators::Rice.new(inputter, outputter, config)
+
+    capture_io do
+      generator.generate
+    end
+
+    classes_cpp = outputter.output_paths.fetch(outputter.output_path("forward_declared_classes-rb.cpp"))
+    all_layers_cpp = outputter.output_paths.fetch(outputter.output_path("forward_declared_all_layers-rb.cpp"))
+
+    refute_includes classes_cpp,
+                    'define_class_under<ForwardDeclaredClasses::ActivationLayer>(rb_mForwardDeclaredClasses, "ActivationLayer")'
+    assert_includes all_layers_cpp,
+                    'define_class_under<ForwardDeclaredClasses::ActivationLayer, ForwardDeclaredClasses::Layer>(rb_mForwardDeclaredClasses, "ActivationLayer")'
+  end
 end