Fix #10464: Match overridden definitions #10531
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| case _ => "not matched" | ||
| } | ||
| '{ println(${Expr(res)}) } | ||
| } |
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The subtle semantics in quoted patterns may cause problems.
Maybe the programmer can change to Reflection for such use cases?
Or, instead of quoted patterns, add extractors to support pattern match on Expr[T] with clear intention and more predictable semantics.
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Yes, less common more precise matching can and must be done using reflection.
The intended semantics have not changed (#10464 (comment)), it was just a bug in the implementation.
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I see, thanks for the explanation 👍
| case _ => "not matched" | ||
| } | ||
| '{ println(${Expr(res)}) } | ||
| } |
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I see, thanks for the explanation 👍
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@nicolasstucki I think the implementation is still incomplete, as it only checks for overridden symbols in one direction!
| private def symbolMatch(scrutinee: Symbol, pattern: Symbol)(using Env): Boolean = | ||
| scrutinee == pattern | ||
| || summon[Env].get(scrutinee).contains(pattern) | ||
| || scrutinee.allOverriddenSymbols.contains(pattern) |
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The semantics still seem incomplete in this implementation.
Consider:
trait A { def foo: Int }
trait B extends A { def foo: Int = 1 }
val e0: Expr[A] = '{ new B }
val e1: Expr[Int] = '{ $e0.foo }The quoted expression e1 will not match a pattern like '{ ($x: B).foo }, but it should.
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