Overlapped pattern warnings for lazy patterns

The compiler appears to disregard lazy patterns when producing overlapped-pattern warnings. Some detectable overlapped patterns are ignored as a result. For example, the following does not produce a warning:

f x = case x of Just ~1 -> 0
                Just _  -> 1
                Nothing -> 2

This function cannot return 1 because every value that satisfies the second pattern also satisfies the first.

I think the relevant instances of overlap could be captured by treating ~() patterns as wildcards for the purpose of detecting overlapped patterns.

Trac metadata

Trac field	Value
Version	6.4.1
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	low
Resolution	Unresolved
Component	Compiler
Test case
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Operating system	Unknown
Architecture	Unknown