This project corrected an assumption I held about how WithComparer and Collect interact.
someValuesProvider
.WithComparer(...)
.Collect()
Despite how it looks, and despite the fact that WithComparer receives an IEqualityComparer<T> rather than an IEqualityComparer<ImmutableArray<T>>, this does not compare individual values from the IncrementalValuesProvider<T> before aggregating them.
When Collect converts the IncrementalValuesProvider<T> to a IncrementalValueProvider<ImmutableArray<T>>, the new provider essentially inherits the old provider's comparer and uses it with Enumerable.SequenceEqual after aggregating the outputs of the old provider.
In other words, the result is exactly the same as if you wrote this and supplied an IEqualityComparer<ImmutableArray<T>> that uses Enumerable.SequenceEqual:
someValuesProvider
.Collect()
.WithComparer(...)
This violates the Principle of Least Astonishment in a big way, but it is what it is.