Restore pre-3.3.2 behavior of inline implicit def
#19877
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`inline implicit def` is not really a supported feature since it combines Scala 3's `inline` with Scala 2's `implicit` where the latter should eventually be deprecated. This however didn't prevent at least one project from using this combination in a way that was broken by scala#18249, see scala#19862 for the details. The issue is that when definining: implicit def foo(x: A): B = ... Then `foo` is a valid implicit search candidate when looking up an implicit `Function1[A, B]`. However, before scala#18249 if instead we wrote: inline implicit def foo(x: A): B = ... Then `foo` would be considered as an implicit search candidate but discarded because eta-expansion was disabled. There is no particular reason for `inline implicit def` to behave differently from `implicit def` here, but since `implicit def` is a legacy feature and since Scala 3.3 is an LTS release, we choose to restore the pre-scala#18249 behavior for compatibility reasons. Fixes scala#19862.
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nicolasstucki
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Mar 5, 2024
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inline implicit defis not really a supported feature since it combines Scala 3'sinlinewith Scala 2'simplicitwhere the latter should eventually be deprecated. This however didn't prevent at least one project from using this combination in a way that was broken by #18249, see #19862 for the details.The issue is that when definining:
Then
foois a valid implicit search candidate when looking up an implicitFunction1[A, B]. However, before #18249 if instead we wrote:Then
foowould be considered as an implicit search candidate but discarded because eta-expansion was disabled.There is no particular reason for
inline implicit defto behave differently fromimplicit defhere, but sinceimplicit defis a legacy feature and since Scala 3.3 is an LTS release, we choose to restore the pre-#18249 behavior for compatibility reasons.Fixes #19862.