Fix quotes with references to path dependent types

Author: nicolasstucki

compiler/src/dotty/tools/dotc/staging/HealType.scala

@@ -30,38 +30,41 @@ class HealType(pos: SrcPos)(using Context) extends TypeMap {
    */
   def apply(tp: Type): Type =
     tp match
-      case tp: TypeRef =>
-        healTypeRef(tp)
-      case tp @ TermRef(NoPrefix, _) if !tp.symbol.isStatic && level > levelOf(tp.symbol) =>
-        levelError(tp.symbol, tp, pos)
+      case tp @ TypeRef(NoPrefix, _) if tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
+        tp
+      case tp @ TypeRef(prefix: TermRef, _) if tp.symbol.isTypeSplice && level > 0 =>
+        checkNotWildcardSplice(tp)
+        getQuoteTypeTags.getTagRef(prefix)
+      case tp @ TypeRef(_: NamedType | _: ThisType | NoPrefix, _) =>
+        if levelInconsistentRootOfPath(tp).exists then
+          val tp1 = tp.dealias
+          if tp1 != tp then apply(tp1)
+          else tryHeal(tp.symbol, tp, pos)
+        else
+          tp
+      case tp: TermRef =>
+        val inconsistentRoot = levelInconsistentRootOfPath(tp)
+        if inconsistentRoot.exists then levelError(inconsistentRoot, tp, pos)
+        else tp
       case tp: AnnotatedType =>
         derivedAnnotatedType(tp, apply(tp.parent), tp.annot)
       case _ =>
         mapOver(tp)
 
-  private def healTypeRef(tp: TypeRef): Type =
-    tp.prefix match
-      case prefix: TermRef if tp.symbol.isTypeSplice =>
-        checkNotWildcardSplice(tp)
-        if level == 0 then tp else getQuoteTypeTags.getTagRef(prefix)
-      case prefix: TermRef if !prefix.symbol.isStatic && level > levelOf(prefix.symbol) =>
-        dealiasAndTryHeal(prefix.symbol, tp, pos)
-      case NoPrefix if level > levelOf(tp.symbol) && !tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
-        dealiasAndTryHeal(tp.symbol, tp, pos)
-      case prefix: ThisType if level > levelOf(prefix.cls) && !tp.symbol.isStatic =>
-        dealiasAndTryHeal(tp.symbol, tp, pos)
-      case _ =>
-        mapOver(tp)
-
   private def checkNotWildcardSplice(splice: TypeRef): Unit =
     splice.prefix.termSymbol.info.argInfos match
       case (tb: TypeBounds) :: _ => report.error(em"Cannot splice $splice because it is a wildcard type", pos)
       case _ =>
 
-  private def dealiasAndTryHeal(sym: Symbol, tp: TypeRef, pos: SrcPos): Type =
-    val tp1 = tp.dealias
-    if tp1 != tp then apply(tp1)
-    else tryHeal(tp.symbol, tp, pos)
+  /** Return the root of this path if it is a variable defined in a previous level.
+   *  If the path is consistent, return NoSymbol.
+   */
+  private def levelInconsistentRootOfPath(tp: Type)(using Context): Symbol =
+    tp match
+      case tp @ NamedType(NoPrefix, _) if level > levelOf(tp.symbol) => tp.symbol
+      case tp: NamedType if !tp.symbol.isStatic => levelInconsistentRootOfPath(tp.prefix)
+      case tp: ThisType if level > levelOf(tp.cls) => tp.cls
+      case _ => NoSymbol
 
   /** Try to heal reference to type `T` used in a higher level than its definition.
    *  Returns a reference to a type tag generated by `QuoteTypeTags` that contains a

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

@@ -157,13 +157,18 @@ class PickleQuotes extends MacroTransform {
         override def apply(tp: Type): Type = tp match
           case tp: TypeRef if tp.typeSymbol.isTypeSplice =>
             apply(tp.dealias)
-          case tp @ TypeRef(pre, _) if pre == NoPrefix || pre.termSymbol.isLocal =>
+          case tp @ TypeRef(pre, _) if pre == NoPrefix || isLocalPath(pre) =>
             val hiBound = tp.typeSymbol.info match
               case info: ClassInfo => info.parents.reduce(_ & _)
               case info => info.hiBound
             apply(hiBound)
           case tp =>
             mapOver(tp)
+
+        private def isLocalPath(tp: Type): Boolean = tp match
+          case TermRef(NoPrefix, _) => true
+          case tp @ TermRef(pre, _) if !tp.symbol.is(Package) => isLocalPath(pre)
+          case _ => false
       }
 
       /** Remove references to local types that will not be defined in this quote */

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

@@ -224,7 +224,7 @@ class Splicing extends MacroTransform:
                 // Dealias references to captured types
                 TypeTree(tree.tpe.dealias)
             else super.transform(tree)
-        case tree: TypeTree =>
+        case _: TypeTree | _: SingletonTypeTree =>
           if containsCapturedType(tree.tpe) && level >= 1 then getTagRefFor(tree)
           else tree
         case tree @ Assign(lhs: RefTree, rhs) =>
@@ -355,7 +355,7 @@ class Splicing extends MacroTransform:
     private def capturedType(tree: Tree)(using Context): Symbol =
       val tpe = tree.tpe.widenTermRefExpr
       val bindingSym = refBindingMap
-        .getOrElseUpdate(tree.symbol, (TypeTree(tree.tpe), newQuotedTypeClassBinding(tpe)))._2
+        .getOrElseUpdate(tree.symbol, (TypeTree(tpe), newQuotedTypeClassBinding(tpe)))._2
       bindingSym
 
     private def capturedPartTypes(tpt: Tree)(using Context): Tree =

tests/pos-macros/path-dependent-type-capture/Macro_1.scala

@@ -0,0 +1,91 @@
+import scala.quoted.*
+
+trait A:
+  type T
+  val b: B
+
+trait B:
+  type T
+  def f: Unit
+
+trait C0:
+  type U
+  val d: D0
+trait D0:
+  type U
+  def h: Unit
+object Macro:
+  inline def generateCode: Unit = ${ generateCodeExpr }
+
+  def generateCodeExpr(using Quotes): Expr[Unit] =
+    '{
+      $testLocalPathsGlobalClasses
+      $testLocalPathsLocalClasses
+      // $testThisPaths // FIXME java.lang.ClassCastException: class scala.quoted.runtime.impl.ExprImpl cannot be cast to class scala.quoted.Type
+    }
+
+  def testLocalPathsGlobalClasses(using Quotes): Expr[Unit] =
+    '{
+      type T
+      val a: A = ???
+      ${
+        val expr = '{
+          val t: T = ???
+          val aT: a.T = ???
+          val abT: a.b.T = ???
+          val aRef: a.type = ???
+          aRef.b
+          aRef.b.f
+          val abRef: a.b.type = ???
+          abRef.f
+        }
+        expr
+      }
+    }
+
+  def testLocalPathsLocalClasses(using Quotes): Expr[Unit] =
+    '{
+      type U
+      trait C extends C0:
+        type U
+        val d: D
+      trait D extends D0:
+        type U
+        def h: Unit
+      val c: C = ???
+      ${
+        val expr = '{
+          val u: U = ???
+          val cU: c.U = ???
+          val cdU: c.d.U = ???
+          val cRef: c.type = ???
+          // cRef.d // FIXME
+          // cRef.d.h // FIXME
+          val cdRef: c.d.type = ???
+          // cdRef.h // FIXME
+        }
+        expr
+      }
+    }
+
+  // def testThisPaths(using Quotes): Expr[Unit] =
+  //   '{
+  //     trait E:
+  //       type V
+  //       val f: F
+  //       ${
+  //         val expr = '{
+  //           val _: Any = this
+  //           val _: Any = f
+  //           val _: this.type = ???
+  //           val _: V = ???
+  //           val _: this.V = ???
+  //           val _: this.f.V = ???
+  //           val _: this.type = ???
+  //           val _: this.f.type = ???
+  //         }
+  //         expr
+  //       }
+  //     trait F:
+  //       type V
+  //   }

tests/pos-macros/path-dependent-type-capture/Test_2.scala

@@ -0,0 +1 @@
+@main def test = Macro.generateCode