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InferencerTest.scala
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InferencerTest.scala
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package scala.tools.nsc
package typechecker
import org.junit.Assert.assertTrue
import org.junit.{After, Before, Test}
import org.junit.runner.RunWith
import org.junit.runners.JUnit4
import scala.tools.testkit.BytecodeTesting
class A
class B extends A
trait C
trait X[+T]
trait Y[T]
trait Z[-T]
trait Quux[-T] extends Z[T]
trait SubZB extends Z[B]
trait ZwC[-T] extends Z[T] with C
@RunWith(classOf[JUnit4])
class InferencerTests extends BytecodeTesting {
import compiler.global._, analyzer._
var storedYscala3ImplicitResolution: Boolean = false
@Before
def storeYscala3ImplicitResolution(): Unit = {
storedYscala3ImplicitResolution = settings.Yscala3ImplicitResolution.value
}
@After
def restoreYscala3ImplicitResolution(): Unit = {
settings.Yscala3ImplicitResolution.value = storedYscala3ImplicitResolution
}
@Test
def isAsSpecificScala2(): Unit = {
settings.Yscala3ImplicitResolution.value = false
val run = new global.Run
enteringPhase(run.typerPhase) {
val XA = typeOf[X[A]]
val XB = typeOf[X[B]]
val YA = typeOf[Y[A]]
val YB = typeOf[Y[B]]
val ZA = typeOf[Z[A]]
val ZB = typeOf[Z[B]]
val LZA = typeOf[List[Z[A]]]
val LZB = typeOf[List[Z[B]]]
val QuuxA = typeOf[Quux[A]]
val QuuxB = typeOf[Quux[B]]
val SubZB = typeOf[SubZB]
val ZBwC = typeOf[ZwC[B]]
// https://github.com/scala/bug/issues/2509
// See discussion at https://github.com/lampepfl/dotty/blob/89540268e6c49fb92b9ca61249e46bb59981bf5a/src/dotty/tools/dotc/typer/Applications.scala#L925-L951
// Covariant
assertTrue(!typer.infer.isAsSpecific(XA, XB))
assertTrue(typer.infer.isAsSpecific(XB, XA))
// Invariant
assertTrue(!typer.infer.isAsSpecific(YA, YB))
assertTrue(!typer.infer.isAsSpecific(YB, YA))
// Contravariant: Scala 2 treats subtype/least derived as most specific
assertTrue(typer.infer.isAsSpecific(ZA, ZB))
assertTrue(!typer.infer.isAsSpecific(ZB, ZA))
// Inner contravariant: Scala 2 treats subtype/least derived as most specific
assertTrue(typer.infer.isAsSpecific(LZA, LZB))
assertTrue(!typer.infer.isAsSpecific(LZB, LZA))
// Subtypes of contravaraint effectively unrelated
assertTrue(!typer.infer.isAsSpecific(ZA, SubZB))
assertTrue(!typer.infer.isAsSpecific(SubZB, ZA))
// Subtypes of contravaraint effectively unrelated
assertTrue(!typer.infer.isAsSpecific(ZA, ZBwC))
assertTrue(!typer.infer.isAsSpecific(ZBwC, ZA))
// Contravariant outer subtypes
assertTrue(!typer.infer.isAsSpecific(ZA, QuuxA))
assertTrue(typer.infer.isAsSpecific(QuuxA, ZA))
assertTrue(!typer.infer.isAsSpecific(ZA, QuuxB))
assertTrue(!typer.infer.isAsSpecific(QuuxB, ZA))
assertTrue(!typer.infer.isAsSpecific(ZB, QuuxA))
assertTrue(typer.infer.isAsSpecific(QuuxA, ZB))
assertTrue(!typer.infer.isAsSpecific(ZB, QuuxB))
assertTrue(typer.infer.isAsSpecific(QuuxB, ZB))
}
}
@Test
def isAsSpecificScala3(): Unit = {
settings.Yscala3ImplicitResolution.value = true
val run = new global.Run
enteringPhase(run.typerPhase) {
val XA = typeOf[X[A]]
val XB = typeOf[X[B]]
val YA = typeOf[Y[A]]
val YB = typeOf[Y[B]]
val ZA = typeOf[Z[A]]
val ZB = typeOf[Z[B]]
val LZA = typeOf[List[Z[A]]]
val LZB = typeOf[List[Z[B]]]
val QuuxA = typeOf[Quux[A]]
val QuuxB = typeOf[Quux[B]]
val SubZB = typeOf[SubZB]
val ZBwC = typeOf[ZwC[B]]
// https://github.com/scala/bug/issues/2509
// See discussion at https://github.com/lampepfl/dotty/blob/89540268e6c49fb92b9ca61249e46bb59981bf5a/src/dotty/tools/dotc/typer/Applications.scala#L925-L951
// Covariant
assertTrue(!typer.infer.isAsSpecific(XA, XB))
assertTrue(typer.infer.isAsSpecific(XB, XA))
// Invariant
assertTrue(!typer.infer.isAsSpecific(YA, YB))
assertTrue(!typer.infer.isAsSpecific(YB, YA))
// Contravariant: treat top level as covariant
assertTrue(!typer.infer.isAsSpecific(ZA, ZB))
assertTrue(typer.infer.isAsSpecific(ZB, ZA))
// Inner contravariant: also changed
assertTrue(!typer.infer.isAsSpecific(LZA, LZB))
assertTrue(typer.infer.isAsSpecific(LZB, LZA))
// Subtypes of contravaraint effectively unrelated
assertTrue(!typer.infer.isAsSpecific(ZA, SubZB))
assertTrue(typer.infer.isAsSpecific(SubZB, ZA))
// Subtypes of contravaraint effectively unrelated
assertTrue(!typer.infer.isAsSpecific(ZA, ZBwC))
assertTrue(typer.infer.isAsSpecific(ZBwC, ZA))
// Contravariant outer subtypes
assertTrue(!typer.infer.isAsSpecific(ZA, QuuxA))
assertTrue(typer.infer.isAsSpecific(QuuxA, ZA))
assertTrue(!typer.infer.isAsSpecific(ZA, QuuxB))
assertTrue(typer.infer.isAsSpecific(QuuxB, ZA))
assertTrue(!typer.infer.isAsSpecific(ZB, QuuxA))
assertTrue(!typer.infer.isAsSpecific(QuuxA, ZB))
assertTrue(!typer.infer.isAsSpecific(ZB, QuuxB))
assertTrue(typer.infer.isAsSpecific(QuuxB, ZB))
}
}
}