Fixes for isLegalPrefix change (#22241)

Fixes #22062
Fixes #22068
Fixes #22070

Author: odersky

compiler/src/dotty/tools/dotc/core/TypeOps.scala

@@ -511,7 +511,22 @@ object TypeOps:
         tp
       else (if pre.isSingleton then NoType else tryWiden(tp, tp.prefix)).orElse {
         if (tp.isTerm && variance > 0 && !pre.isSingleton)
-          apply(tp.info.widenExpr)
+          tp.prefix match
+            case inlines.Inliner.OpaqueProxy(ref) =>
+              // Strip refinements on an opaque alias proxy
+              // Using pos/i22068 as an example,
+              // Inliner#addOpaqueProxies add the following opaque alias proxy:
+              //     val $proxy1: foos.type { type Foo[T] = String } =
+              //       foos.$asInstanceOf[foos.type { type Foo[T] = String }]
+              // Then when InlineCall#expand creates a typed Inlined,
+              // we type avoid any local bindings, which includes that opaque alias proxy.
+              // To avoid that the replacement is a non-singleton RefinedType,
+              // we drop the refinements too and return foos.type.
+              // That way, when we inline `def m1` and we calculate the asSeenFrom
+              // of `b1.and(..)` b1 doesn't have an unstable prefix.
+              derivedSelect(tp, ref)
+            case _ =>
+              apply(tp.info.widenExpr)
         else if (upper(pre).member(tp.name).exists)
           super.derivedSelect(tp, pre)
         else

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -395,9 +395,10 @@ class TreeUnpickler(reader: TastyReader,
             case TYPEREFin =>
               val name = readName().toTypeName
               val prefix = readType()
+              def pre = if TypeOps.isLegalPrefix(prefix) then prefix else QualSkolemType(prefix)
               val space = readType()
               space.decl(name) match {
-                case symd: SymDenotation if prefix.isArgPrefixOf(symd.symbol) => TypeRef(prefix, symd.symbol)
+                case symd: SymDenotation if prefix.isArgPrefixOf(symd.symbol) => TypeRef(pre, symd.symbol)
                 case _ => TypeRef(prefix, name, space.decl(name).asSeenFrom(prefix))
               }
             case REFINEDtype =>

compiler/src/dotty/tools/dotc/inlines/Inliner.scala

@@ -131,6 +131,39 @@ object Inliner:
           case _ => tree
       else super.transformInlined(tree)
   end InlinerMap
+
+  object OpaqueProxy:
+
+    def apply(ref: TermRef, cls: ClassSymbol, span: Span)(using Context): TermRef =
+      def openOpaqueAliases(selfType: Type): List[(Name, Type)] = selfType match
+        case RefinedType(parent, rname, TypeAlias(alias)) =>
+          val opaq = cls.info.member(rname).symbol
+          if opaq.isOpaqueAlias then
+            (rname, alias.stripLazyRef.asSeenFrom(ref, cls))
+            :: openOpaqueAliases(parent)
+          else Nil
+        case _ => Nil
+      val refinements = openOpaqueAliases(cls.givenSelfType)
+      val refinedType = refinements.foldLeft(ref: Type): (parent, refinement) =>
+        RefinedType(parent, refinement._1, TypeAlias(refinement._2))
+      val refiningSym = newSym(InlineBinderName.fresh(), Synthetic, refinedType, span)
+      refiningSym.termRef
+
+    def unapply(refiningRef: TermRef)(using Context): Option[TermRef] =
+      val refiningSym = refiningRef.symbol
+      if refiningSym.name.is(InlineBinderName) && refiningSym.is(Synthetic, butNot=InlineProxy) then
+        refiningRef.info match
+          case refinedType: RefinedType => refinedType.stripRefinement match
+            case ref: TermRef => Some(ref)
+            case _ => None
+          case _ => None
+      else
+        None
+
+  end OpaqueProxy
+
+  private[inlines] def newSym(name: Name, flags: FlagSet, info: Type, span: Span)(using Context): Symbol =
+    newSymbol(ctx.owner, name, flags, info, coord = span)
 end Inliner
 
 /** Produces an inlined version of `call` via its `inlined` method.
@@ -189,7 +222,7 @@ class Inliner(val call: tpd.Tree)(using Context):
   private val bindingsBuf = new mutable.ListBuffer[ValOrDefDef]
 
   private[inlines] def newSym(name: Name, flags: FlagSet, info: Type)(using Context): Symbol =
-    newSymbol(ctx.owner, name, flags, info, coord = call.span)
+    Inliner.newSym(name, flags, info, call.span)
 
   /** A binding for the parameter of an inline method. This is a `val` def for
    *  by-value parameters and a `def` def for by-name parameters. `val` defs inherit
@@ -351,20 +384,9 @@ class Inliner(val call: tpd.Tree)(using Context):
              && (forThisProxy || inlinedMethod.isContainedIn(cls))
              && mapRef(ref).isEmpty
           then
-            def openOpaqueAliases(selfType: Type): List[(Name, Type)] = selfType match
-              case RefinedType(parent, rname, TypeAlias(alias)) =>
-                val opaq = cls.info.member(rname).symbol
-                if opaq.isOpaqueAlias then
-                  (rname, alias.stripLazyRef.asSeenFrom(ref, cls))
-                  :: openOpaqueAliases(parent)
-                else Nil
-              case _ =>
-                Nil
-            val refinements = openOpaqueAliases(cls.givenSelfType)
-            val refinedType = refinements.foldLeft(ref: Type) ((parent, refinement) =>
-              RefinedType(parent, refinement._1, TypeAlias(refinement._2))
-            )
-            val refiningSym = newSym(InlineBinderName.fresh(), Synthetic, refinedType).asTerm
+            val refiningRef = OpaqueProxy(ref, cls, call.span)
+            val refiningSym = refiningRef.symbol.asTerm
+            val refinedType = refiningRef.info
             val refiningDef = ValDef(refiningSym, tpd.ref(ref).cast(refinedType), inferred = true).withSpan(span)
             inlining.println(i"add opaque alias proxy $refiningDef for $ref in $tp")
             bindingsBuf += refiningDef
@@ -768,6 +790,7 @@ class Inliner(val call: tpd.Tree)(using Context):
     override def typedSelect(tree: untpd.Select, pt: Type)(using Context): Tree = {
       val locked = ctx.typerState.ownedVars
       val qual1 = typed(tree.qualifier, shallowSelectionProto(tree.name, pt, this, tree.nameSpan))
+      selectionType(tree, qual1) // side-effect
       val resNoReduce = untpd.cpy.Select(tree)(qual1, tree.name).withType(tree.typeOpt)
       val reducedProjection = reducer.reduceProjection(resNoReduce)
       if reducedProjection.isType then

compiler/src/dotty/tools/dotc/transform/ResolveSuper.scala

@@ -109,8 +109,8 @@ object ResolveSuper {
         sym = other.symbol
         // Having a matching denotation is not enough: it should also be a subtype
         // of the superaccessor's type, see i5433.scala for an example where this matters
-        val otherTp = other.asSeenFrom(base.typeRef).info
-        val accTp = acc.asSeenFrom(base.typeRef).info
+        val otherTp = other.asSeenFrom(base.thisType).info
+        val accTp = acc.asSeenFrom(base.thisType).info
         // Since the super class can be Java defined,
         // we use relaxed overriding check for explicit nulls if one of the symbols is Java defined.
         // This forces `Null` to be a subtype of non-primitive value types during override checking.

tests/pos/i22062.scala

@@ -0,0 +1,32 @@
+class Label
+class Component
+
+trait RenderableCellsCompanion:
+  type Renderer[-A] <: CellRenderer[A]
+  type DefaultRenderer[-A] <: Label & Renderer[A]
+
+  trait CellRendererCompanion:
+    type CellInfo
+    def labeled[A](): DefaultRenderer[A]
+    protected trait LabelRenderer[-A] extends CellRenderer[A]:
+      override abstract def componentFor(info: companion.CellInfo): Component = super.componentFor(info)
+
+  trait CellRenderer[-A]:
+    val companion: CellRendererCompanion
+    def componentFor(cellInfo: companion.CellInfo): Component
+
+sealed trait TreeRenderers extends RenderableCellsCompanion:
+  this: Tree.type =>
+
+  trait Renderer[-A] extends CellRenderer[A]:
+    final override val companion = Renderer
+
+  object Renderer extends CellRendererCompanion:
+    final override class CellInfo
+    override def labeled[A]() = new DefaultRenderer[A] with LabelRenderer[A] {}
+
+  class DefaultRenderer[-A] extends Label with Renderer[A]:
+    override def componentFor(info: Renderer.CellInfo): Component = ???
+
+class Tree extends Component
+object Tree extends TreeRenderers

tests/pos/i22068.less-min.scala

@@ -0,0 +1,21 @@
+class A
+class B extends A
+class C extends A
+
+object foos:
+  opaque type Tag[A] = String
+  object Tag:
+    inline given mkTag[A]: Tag[A] = ???
+    type Full[A] = Tag[A] | Set[A]
+    sealed trait Set[A] extends Any
+    case class Union[A](tags: Seq[Tag[Any]]) extends AnyVal with Set[A]:
+      infix def and[B](t2: Full[B]): Unit = ???
+    object Union:
+      inline given mkUnion[A]: Union[A] = ???
+import foos.Tag.*
+
+class Test:
+  inline def m1[K1, K2](using b1: Union[K1], b2: Union[K2]): Unit =
+    b1.and(b2)
+
+  def t1(): Unit = m1[B | C, A]

tests/pos/i22068.orig.scala

@@ -0,0 +1,29 @@
+trait AnyFreeSpecLike:
+  inline implicit def convertToFreeSpecStringWrapper(s: String): FreeSpecStringWrapper = ???
+  protected final class FreeSpecStringWrapper(string: String):
+    infix def in(testFun: => Any): Unit = ???
+
+
+import types.Tag.*
+class TagTest extends AnyFreeSpecLike{
+  inline def test[T1, T2](using k1: Union[T1], k2: Union[T2]): Unit =
+    "T1 <:< T2" in {
+        val kresult = k1 <:< k2
+        ???
+    }
+  class A
+  class B extends A
+  class C extends A
+  test[B | C, A]
+}
+
+object types:
+  opaque type Tag[A] = String
+  object Tag:
+    inline given apply[A]: Tag[A] = ???
+    type Full[A] = Tag[A] | Set[A]
+    sealed trait Set[A] extends Any
+    case class Union[A](tags: Seq[Tag[Any]]) extends AnyVal with Set[A]:
+      infix def <:<[B](t2: Full[B]): Boolean = ???
+    object Union:
+      inline given apply[A]: Union[A] = ???

tests/pos/i22068.scala

@@ -0,0 +1,14 @@
+object foos:
+  opaque type Foo[T] = String
+  object bars:
+    class Bar1[A] { def and(b: Bar2): Unit = () }
+    class Bar2
+    inline def mkBar1[A]: Bar1[A] = new Bar1[A]
+           def mkBar2   : Bar2    = new Bar2
+import foos.*, bars.*
+
+class Test:
+  inline def m1[X](b1: Bar1[X], b2: Bar2): Unit =
+    b1.and(b2)
+
+  def t1(): Unit = m1(mkBar1[Int], mkBar2)

tests/pos/i22070/macro.scala

@@ -0,0 +1,18 @@
+trait Featureful[T]:
+  def toFeatures(value: T): IArray[Float]
+
+object Featureful:
+  inline def derived[T](using scala.deriving.Mirror.Of[T]) = ${ derivedImpl[T] }
+
+  import scala.quoted.*
+  private def derivedImpl[T: Type](using Quotes): Expr[Featureful[T]] =
+    import quotes.reflect.*
+    '{
+      new Featureful[T]:
+        def toFeatures(value: T) =
+          val feats   = IArray.empty[Featureful[?]]
+          val product = value.asInstanceOf[Product]
+          product.productIterator.zipWithIndex.foreach: (any, idx) =>
+            feats(idx).toFeatures(any.asInstanceOf)
+          IArray.empty
+    }

tests/pos/i22070/usage.scala

@@ -0,0 +1 @@
+case class Breaks(x: Boolean, y: Boolean) derives Featureful