So first, this paragraph was rebranded for "non-generic containers" whereas it indeed also concerns this case:
as the first paragraph states it.
We agreed on discouraging this but it looks like this paragraph is also about it.
Another point is that in the RI, we also throw an exception in this case:
even if we have only one VE defined for the key and no VE defined for the value.
2 things here:
not sure throwing an exception is the best we can do
if we consider we should throw an exception, then we should take this case into account in the resolution algorithm
, I'll change the section title.
On your second question, the RI seems to violate the spec here. It says
If the constraint carries the Unwrapping.Unwrap payload and there is exactly one maximally-specific type-compliant value extractor, this extractor is applied
So the exception seems not justified. Can you file an HV issue?