Fix 11018 - consistency of trait parameters #11059
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| val baseClasses: List[ClassSymbol] = clazz.info.baseClasses | ||
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| // tracks types that we have seen for a particular base class in baseClasses | ||
| val seenTypes = mutable.Map.empty[Symbol, List[Type]] |
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The original Scala 2 code used an Array since baseClasses where stored in a Seq and allowed indexing into the array. Do you think it is a performance problem to use a Map here instead?
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Performance of register was mentioned here: scala/scala@42fb66a
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We have a specialized MutableSymbolMap that you probably want to use here.
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An alternative to using a map here would be to use a set which should be good enough to detect one error and stop.
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Looks like you tried something like this but ended up reverting it: https://github.com/lampepfl/dotty/compare/2201e3da859ced8edb9da7a71a931cd2bc5cc395..fe73b0b5371d5b4181c1a98be2dc881981c0b526, was there an issue with it?
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Yes, it actually was not semantics preserving and caused some regressions -- So I just reverted it.
| // ported from Scala 2: | ||
| // https://github.com/scala/scala/blob/9bb659e62a9239c01aec14c171f8598bb1a576fe/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala#L834-L883 | ||
| def validateBaseTypes(): Unit = { | ||
| val tpe = clazz.thisType // in Scala 2 this was clazz.tpe |
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Here is also a difference from Scala 2, where I use thisType and Scala 2 used .tpe.
Error: -- [E006] Not Found Error: /__w/dotty/dotty/compiler/src/dotty/tools/dotc/typer/RefChecks.scala:820:12
Error: 820 | unreachable()
Error: | ^^^^^^^^^^^
Error: | Not found: unreachableChange the first line of the file from: package dotty.tools.dotcto: package dotty.tools
package dotcto make the package object of dotty.tools where unreachable is defined in scope. |
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I've gone ahead and pushed the fix I mentioned. |
Check conformance of trait and class parameters of base types. This PR attempts to solve #11018 by incorporating an additional check.
However, it might be too conservative as it also rules out a positive example of #3989.