Disable distribution of intersection types over applied types#23441
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odersky merged 16 commits intoscala:mainfrom Sep 13, 2025
Merged
Disable distribution of intersection types over applied types#23441odersky merged 16 commits intoscala:mainfrom
odersky merged 16 commits intoscala:mainfrom
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EugeneFlesselle
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And add minimization
Instead of AppliedType of OrTypes, which relied on the distribution of AndTypes when inheriting multiple context bound companions of the same name
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odersky
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To be conservative I'd make the main change in distributeAnd conditional on a source version or a -Y flag. That would give applications that critically rely on the unsoundness a way out.
This reverts commit 0441af0 to resolve merge conflict
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Looks good, thanks for squeezing these changes in your busy schedule!
hamzaremmal
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Starting from Scala 3.8.0, the following code will not compile due to removing some unsound typing rules. See scala/scala3#23441 Co-authored-by: Eugene Flesselle <eugene@flesselle.net>
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Fixes soundness issue #23435
Note in particular that this implies we cannot (indirectly) inherit multiple instantiations of the same trait. E.g., see tests/neg/conflicting-inst-basetypes.scala.
The impact on the community-build appears to be rather reasonable, tweaks are required:
The changes should be relatively well regrouped by commit for review.