Merge pull request #406 from sjrd/fix-path-dependent-opaque-erasure

Fix #403: Take the prefix of opaque type aliases into account in erasure.
scalacenter · Nov 30, 2023 · ee609d3 · ee609d3
2 parents b8008da + 9eb273a
commit ee609d3
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Showing 4 changed files with 36 additions and 16 deletions.
diff --git a/tasty-query/shared/src/main/scala/tastyquery/Erasure.scala b/tasty-query/shared/src/main/scala/tastyquery/Erasure.scala
@@ -55,13 +55,12 @@ private[tastyquery] object Erasure:
         else ClassRef(cls).arrayOf()
       case tpe: TypeRef =>
         tpe.optSymbol match
-          case Some(sym: TypeMemberSymbol) =>
-            sym.typeDef match
-              case TypeMemberDefinition.TypeAlias(alias)          => arrayOf(alias)
-              case TypeMemberDefinition.AbstractType(bounds)      => arrayOfBounds(bounds)
-              case TypeMemberDefinition.OpaqueTypeAlias(_, alias) => arrayOf(alias)
+          case Some(sym: TypeMemberSymbol) if sym.isOpaqueTypeAlias =>
+            arrayOf(tpe.translucentSuperType)
           case _ =>
-            arrayOfBounds(tpe.bounds)
+            tpe.bounds match
+              case bounds: AbstractTypeBounds => arrayOfBounds(bounds)
+              case TypeAlias(alias)           => arrayOf(alias)
       case tpe: TypeParamRef    => arrayOfBounds(tpe.bounds)
       case tpe: Type            => preErase(tpe, keepUnit = false).arrayOf()
       case tpe: WildcardTypeArg => arrayOfBounds(tpe.bounds)
@@ -81,15 +80,7 @@ private[tastyquery] object Erasure:
         if !keepUnit && cls.isUnit then ClassRef(defn.ErasedBoxedUnitClass)
         else ClassRef(cls)
       case tpe: TypeRef =>
-        tpe.optSymbol match
-          case Some(sym: TypeMemberSymbol) =>
-            sym.typeDef match
-              case TypeMemberDefinition.OpaqueTypeAlias(_, alias) =>
-                preErase(alias, keepUnit)
-              case _ =>
-                preErase(tpe.underlying, keepUnit)
-          case _ =>
-            preErase(tpe.underlying, keepUnit)
+        preErase(tpe.translucentSuperType, keepUnit)
       case tpe: SingletonType =>
         preErase(tpe.underlying, keepUnit)
       case tpe: TypeParamRef =>

diff --git a/tasty-query/shared/src/main/scala/tastyquery/Types.scala b/tasty-query/shared/src/main/scala/tastyquery/Types.scala
@@ -1312,7 +1312,7 @@ object Types {
     private[tastyquery] override def translucentSuperType(using Context): Type = optSymbol match
       case Some(sym: TypeMemberSymbol) =>
         sym.typeDef match
-          case TypeMemberDefinition.OpaqueTypeAlias(_, alias) => alias
+          case TypeMemberDefinition.OpaqueTypeAlias(_, alias) => alias.asSeenFrom(prefix, sym.owner)
           case _                                              => underlying
       case _ =>
         underlying

diff --git a/tasty-query/shared/src/test/scala/tastyquery/SignatureSuite.scala b/tasty-query/shared/src/test/scala/tastyquery/SignatureSuite.scala
@@ -211,6 +211,16 @@ class SignatureSuite extends UnrestrictedUnpicklingSuite:
     assertSigned(mOpaqueWithBounds, "(scala.Null):scala.Null")
   }
 
+  testWithContext("path-dependent-opaque-type-alias") {
+    val PathDependentOpaqueBarClass = ctx.findStaticClass("simple_trees.PathDependentOpaque.Bar")
+
+    val bar = PathDependentOpaqueBarClass.findNonOverloadedDecl(termName("bar"))
+    assertSigned(bar, "(java.lang.String):scala.Unit")
+
+    val get = PathDependentOpaqueBarClass.findNonOverloadedDecl(termName("get"))
+    assertSigned(get, "():java.lang.String")
+  }
+
   testWithContext("scala2-case-class-varargs") {
     val StringContext = ctx.findTopLevelClass("scala.StringContext")
 

diff --git a/test-sources/src/main/scala/simple_trees/PathDependentOpaque.scala b/test-sources/src/main/scala/simple_trees/PathDependentOpaque.scala
@@ -0,0 +1,19 @@
+package simple_trees
+
+object PathDependentOpaque:
+  trait Foo[T]:
+    opaque type Type <: T = T
+
+    protected def make(t: T): Type = t
+  end Foo
+
+  class Bar extends Foo[String]:
+    def bar(x: Type): Unit = ()
+
+    def get(): Type = make("hello")
+  end Bar
+
+  def test(): Unit =
+    val b = new Bar()
+    b.bar(b.get())
+end PathDependentOpaque