Relax avoidance checks more for match type reduction #15036
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TypeParamRefs in match types do not have a corresponding TypeVar so they get assigned level Int.MaxValue by default, this means they can refer to variables at any level, but to avoid a crash in i14921 we also need the reverse direction (they can appear in the bounds of variables of any level), both direction should be safe because these constraints only exist during match type reduction (see `MatchType#reduced`). Fixes scala#14921.
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I believe this should be backported since it fixes a regression introduced in 3.1.2. |
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This backports scala#15036 which fixes a regression introduced in 3.1.2.
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TypeParamRefs in match types do not have a corresponding TypeVar so they get
assigned level Int.MaxValue by default, this means they can refer to variables
at any level, but to avoid a crash in i14921 we also need the reverse
direction (they can appear in the bounds of variables of any level), both
direction should be safe because these constraints only exist during match type
reduction (see
MatchType#reduced).Fixes #14921.