CNA-BUG-086: GameComponent::Dispose(true) does not remove the component from Game.Components

CNA snapshot 009d40f5  ·  Known Issues › Current bugs  ·  source links pinned to 009d40f5

XNA 4.0's GameComponent.Dispose(bool) removes the component from its Game's Components before raising Disposed; CNA only raises Disposed, so a component disposed to retire it keeps being updated and drawn.

Identifier

CNA-BUG-086

Category

Bug

Subsystem

Core & runtime

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Severity

Medium (a triage suggestion, not a project priority)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

None

Affected contract

Microsoft::Xna::Framework::GameComponent::Dispose(bool) (and DrawableGameComponent::Dispose(bool), which calls it)

Expected behaviour

XNA 4.0 (IL of GameComponent.Dispose(bool)): when disposing, under a lock on the component, if (Game != null) Game.Components.Remove(this), then raise Disposed.

Actual behaviour at TARGET

GameComponent.cpp sets disposed_ and raises Disposed; it never touches Game.Components. Update and Draw have no disposed guard, so the XNA idiom "dispose the pause menu to make it go away" leaves the component registered and running.

Source locations

• modules/runtime/src/GameComponent.cpp — GameComponent::Dispose(bool)
• modules/runtime/src/DrawableGameComponent.cpp — DrawableGameComponent::Dispose(bool) forwards to it

Evidence

Checked by reading the named sources at 009d40f5; nothing was built or executed for this entry. XNA behaviour from the genuine XNA 4.0 Game IL. The site's components deep dive already warns about this divergence.

Focused reproduction

// Illustrative; not compiled or run for this entry.
auto menu = std::make_shared<PauseMenu>(game);   // a DrawableGameComponent
game.getComponentsProperty().Add(menu);
// ... later, to close it the XNA way:
menu->Dispose();
// XNA: removed from Components, no more Update/Draw.
// CNA: still in Components; Update/Draw keep running on a disposed object.

Current tests

GameComponentTests.cpp and DrawableGameComponentTests.cpp do not dispose a registered component.

Regression test

A test that adds a component, disposes it, and asserts that Components.Contains is false and that ComponentRemoved was raised before Disposed.

Blast radius

Games that retire components by disposing them. Games that call Components.Remove explicitly are unaffected.

Workaround

Remove the component from Game.Components before disposing it.