Dealias type references when healing types in quotes

We where only doing the dealiasing if the type had no prefix but missed
it if the type reference was on some path.

Fixes #17037

Author: nicolasstucki

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

@@ -192,11 +192,9 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
         case tp: TypeRef =>
           tp.prefix match
             case NoPrefix if level > levelOf(tp.symbol) && !tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
-              val tp1 = tp.dealias
-              if tp1 != tp then apply(tp1)
-              else tryHeal(tp.symbol, tp, pos)
+              tryHealTypeOfType(tp.symbol, tp, pos)
             case prefix: ThisType if !tp.symbol.isStatic && level > levelOf(prefix.cls) =>
-              tryHeal(tp.symbol, tp, pos)
+              tryHealTypeOfType(tp.symbol, tp, pos)
             case prefix: TermRef if tp.symbol.isTypeSplice =>
               prefix.symbol.info.argInfos match
                 case (tb: TypeBounds) :: _ =>
@@ -205,7 +203,7 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
               // Heal explicit type splice in the code
               if level > 0 then getQuoteTypeTags.getTagRef(prefix) else tp
             case prefix: TermRef if !prefix.symbol.isStatic && level > levelOf(prefix.symbol) =>
-              tryHeal(prefix.symbol, tp, pos)
+              tryHealTypeOfType(prefix.symbol, tp, pos)
             case _ =>
               mapOver(tp)
         case tp @ TermRef(NoPrefix, _) if !tp.symbol.isStatic && level > levelOf(tp.symbol) =>
@@ -217,6 +215,17 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
           derivedAnnotatedType(tp, apply(tp.parent), tp.annot.derivedAnnotation(newAnnotTree))
         case _ =>
           mapOver(tp)
+
+    /** Try to dealias or 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]]}`.
+     *  Emits and error if `T` cannot be healed and returns `T`.
+     */
+    private def tryHealTypeOfType(sym: Symbol, tp: TypeRef, pos: SrcPos)(using Context): Type = {
+      val tp1 = tp.dealias
+      if tp1 != tp then apply(tp1)
+      else tryHeal(tp.symbol, tp, pos)
+    }
   }
 
   /** Check phase consistency of terms and heal inconsistent type references. */

tests/pos-macros/i17037.scala

@@ -0,0 +1,8 @@
+import scala.quoted.*
+
+class Foo:
+  type Bar = Int
+
+def macroImpl(using Quotes) =
+  val foo = new Foo
+  Type.of[foo.Bar]

tests/pos-macros/i17037b.scala

@@ -0,0 +1,10 @@
+import scala.quoted.*
+
+class Foo:
+  type Bar = Int
+
+def macroImpl(using Quotes) =
+  val foo = Foo()
+  Type.of[foo.Bar] match
+    case '[foo.Bar] => '{true}
+    case _ => '{false}

tests/pos-macros/i17037c.scala

@@ -0,0 +1,7 @@
+import scala.quoted.*
+
+class Foo:
+  type Bar = Int
+  def macroImpl(using Quotes) =
+    val foo = new Foo
+    Type.of[this.Bar]