Fix quotes with references to path dependent types (#17081)

Author: nicolasstucki

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

@@ -31,39 +31,52 @@ class HealType(pos: SrcPos)(using Context) extends TypeMap {
    */
   def apply(tp: Type): Type =
     tp match
-      case tp: TypeRef =>
-        tp.underlying match
-          case TypeAlias(alias)
-          if !tp.symbol.isTypeSplice && !tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
-            this.apply(alias)
-          case _ =>
-            healTypeRef(tp)
-      case tp @ TermRef(NoPrefix, _) if !tp.symbol.isStatic && level > levelOf(tp.symbol) =>
-        levelError(tp.symbol, tp, pos)
+      case NonSpliceAlias(aliased) => this.apply(aliased)
+      case tp: TypeRef => healTypeRef(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 NoPrefix if tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
+        tp
       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) =>
-        tryHeal(prefix.symbol, tp, pos)
-      case NoPrefix if level > levelOf(tp.symbol) && !tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
-        tryHeal(tp.symbol, tp, pos)
-      case prefix: ThisType if level > levelOf(prefix.cls) && !tp.symbol.isStatic =>
-        tryHeal(tp.symbol, tp, pos)
+      case _: NamedType | _: ThisType | NoPrefix =>
+        if levelInconsistentRootOfPath(tp).exists then
+          tryHeal(tp.symbol, tp, pos)
+        else
+          tp
       case _ =>
         mapOver(tp)
 
+  private object NonSpliceAlias:
+    def unapply(tp: TypeRef)(using Context): Option[Type] = tp.underlying match
+      case TypeAlias(alias) if !tp.symbol.isTypeSplice && !tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) => Some(alias)
+      case _ => None
+
   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 _ =>
 
+  /** 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
    *  reference to a type alias containing the equivalent of `${summon[quoted.Type[T]]}`.

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 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 NoPrefix => true
+          case tp: TermRef if !tp.symbol.is(Package) => isLocalPath(tp.prefix)
+          case tp => false
       }
 
       /** Remove references to local types that will not be defined in this quote */

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

@@ -679,7 +679,7 @@ object TreeChecker {
               defn.AnyType
             case tpe => tpe
           defn.QuotedExprClass.typeRef.appliedTo(tpe)
-        else defn.QuotedTypeClass.typeRef.appliedTo(arg.typeOpt)
+        else defn.QuotedTypeClass.typeRef.appliedTo(arg.typeOpt.widenTermRefExpr)
       }
       val expectedResultType =
         if isTermHole then defn.QuotedExprClass.typeRef.appliedTo(tpt.typeOpt)
@@ -688,7 +688,7 @@ object TreeChecker {
         defn.FunctionOf(List(defn.QuotesClass.typeRef), expectedResultType, isContextual = true)
       val expectedContentType =
         defn.FunctionOf(argQuotedTypes, contextualResult)
-      assert(content.typeOpt =:= expectedContentType, i"expected content of the hole to be ${expectedContentType} but got ${content.typeOpt}")
+      assert(content.typeOpt =:= expectedContentType, i"unexpected content of hole\nexpected: ${expectedContentType}\nwas: ${content.typeOpt}")
 
       tree1
     }

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

@@ -0,0 +1,70 @@
+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
+    }
+
+  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
+          cRef.d.h
+          val cdRef: c.d.type = ???
+          cdRef.h
+          ()
+        }
+        expr
+      }
+    }

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

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