C++/WinRT events don't gracefully handle invalid tokens

[kennykerr]

The winrt::event<Delegate> implementation does not gracefully handle the case where its remove method is called with an invalid token value (a value not present in the array). This update brings the implementation in line with WRL, which handles this scenario.

Tests have been added to validate this scenario.

[JohnTasler]

    slim_mutex m_change;

Why is this needed? Isn't a swap within the scope of a "change"?

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Refers to: src/tool/cpp/cppwinrt/strings/base_events.h:502 in 36d83b4. [](commit_id = 36d83b4, deletion_comment = False)

[kennykerr]

@JohnTasler GitHub’s PR viewer is horrible. Unfortunately, if you leave a comment on a line of code outside of the PR then I cannot reply to it.

Briefly, the m_change lock ensures that add/remove are synchronized while m_swap only protects swapping the targets array. This improves concurrency because the latter happens more frequently and we don’t want it to block on the former.

[JohnTasler]

    }

Since you always access m_targets within a lock, it seems like you need one here. And, do you ever reset m_targets back to nullptr?

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Refers to: src/tool/cpp/cppwinrt/strings/base_events.h:353 in 36d83b4. [](commit_id = 36d83b4, deletion_comment = False)

[JohnTasler]

Sorry. I wanted to grok and review the whole class. I'm using CodeFlow.

It's not a perfect integration, but works pretty well:
https://www.1eswiki.com/wiki/CodeFlow_integration_with_GitHub_Pull_Requests

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In reply to: 453295948 [](ancestors = 453295948)

[Scottj1s]