[Blazor] OwningComponentBase Dispose method in .NET 10 gets back the original behavior

[ilonatommy]

Fixes #64669.

In .NET 9, when a Blazor component was disposed, it called IDisposable.Dispose() which invoked Dispose(bool disposing) with disposing=true. In .NET 10, after PR #62583 added IAsyncDisposable support, the Blazor framework started calling IAsyncDisposable.DisposeAsync() instead. Following the standard .NET dispose pattern, DisposeAsync() called Dispose(false) to avoid double-disposal of managed resources. This broke user code that overrode Dispose(bool disposing) and expected disposing=true when the component was being cleaned up, causing any logic inside if (disposing) { ... } blocks to no longer execute. The fix ensures Dispose(true) is called from DisposeAsync() to maintain backward compatibility while still properly handling async disposal of the service scope.

Changes

• Call Dispose(true) from DisposeAsync() to ensure user overrides of Dispose(bool disposing) receive [disposing=true], maintaining backward compatibility with .NET 9 behavior.
• Removed IsDisposed = true from DisposeAsyncCore()] - the responsibility of setting this flag is in the Dispose(bool disposing) method to avoid duplication and ensure consistency whether disposal happens via sync or async path.

Tests

• DisposeAsync_CallsDispose_WithDisposingTrue - Verifies that DisposeAsync() passes disposing=true to user overrides of Dispose(bool disposing), which is the core fix for issue.
• DisposeAsync_ThenDispose_IsIdempotent - Ensures that calling both DisposeAsync() and Dispose() doesn't cause double-disposal of resources, proving the implementation is safe for multiple disposal calls.
• ComplexComponent_DisposesResourcesOnlyWhenDisposingIsTrue - Demonstrates that with the fix (disposing=true), components with non-trivial disposal logic (timers, cancellation tokens, events) properly clean up managed resources.

[Copilot]

Pull request overview

This PR fixes a backward compatibility issue introduced in .NET 10 where components overriding Dispose(bool disposing) with logic inside if (disposing) { ... } blocks stopped working correctly. The framework now calls DisposeAsync() instead of Dispose(), and the previous implementation passed disposing=false to avoid double-disposal, which broke user code expecting disposing=true.

Key Changes:

• Modified DisposeAsync() to call Dispose(disposing: true) instead of Dispose(disposing: false) to restore backward compatibility with .NET 9 behavior
• Moved IsDisposed = true assignment to the Dispose(bool) method to centralize disposal state management
• Fixed two spelling errors in XML documentation comments ("inhertidoc" → "inheritdoc")

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/Components/Components/src/OwningComponentBase.cs	Updated disposal pattern to call Dispose(true) from DisposeAsync() for backward compatibility, centralized IsDisposed flag management, and fixed XML doc comment typos
src/Components/Components/test/OwningComponentBaseTest.cs	Added regression test to verify Dispose(bool disposing) receives disposing=true when disposed via DisposeAsync()

[oroztocil]

Do we have any components with non-trivial dispose logic on hand? So that we could check that they do not break after change (with double dispose, not executing some code that was executed before, etc.)?

[javiercn]

Some further thoughts

[javiercn]

We don't have to protect against double Dispose; the framework is responsible for correctly disposing the components only Once. Ideally we should just be passing Dispose(disposing: true) instead of false.

[javiercn]

/backport to release/10.0

[github-actions]

Started backporting to release/10.0 (link to workflow run)