Fix #9717: Fix typed tree copier for Selects over Nothing #9856
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Typed tree copier would assign a `a.b` where `a` has type `Nothing` the type `Nothing`. This is wrong, for instance when `b` is $asInstanceOf$ over a value of type `Nothing`, which is the case in i9717.scala
Also treat TermRefs with Nothing types as bottom types. In i9717/Test.scala we got a redundant cast `js.native.$asInstanceOf$[A with B]` because a nottom test did not trigger. The crash due to that cast has been fixed, but it's still better to avoid the cast altogether.
smarter
approved these changes
Sep 24, 2020
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Typed tree copier would assign a$asInstanceOf$
a.bwhereahas typeNothingthe type
Nothing. This is wrong, for instance whenbisover a value of type
Nothing, which is the case in i9717.scala