Fix quoted path dependent types

Fixes #8100
Fixes #12440

Author: nicolasstucki

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

@@ -66,8 +66,14 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
       checkAnnotations(tree)
       super.transform(tree)
     else tree match {
-
-      case _: TypeTree | _: RefTree if tree.isType  =>
+      case tree: TypeTree  =>
+        val tree1 = treeify(tree)
+        if tree ne tree1 then transform(tree1.withSpan(tree.span))
+        else
+          val healedType = healType(tree.srcPos)(tree.tpe)
+          if healedType == tree.tpe then tree
+          else TypeTree(healedType).withSpan(tree.span)
+      case _: RefTree if tree.isType  =>
         val healedType = healType(tree.srcPos)(tree.tpe)
         if healedType == tree.tpe then tree
         else TypeTree(healedType).withSpan(tree.span)
@@ -275,6 +281,18 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
     tp
   }
 
+  /** Transform a TypeTree into a tree that contains the structure of the type */
+  private def treeify(tree: TypeTree)(using Context): Tree =
+    tree.tpe.stripTypeVar.dealias match
+      case tpe @ TypeRef(path: TermRef, _) =>
+        // Expand TypeTree(`x.T`) to Select(`x`, `T`)
+        // Needed in PickleQuotes in case x refers to a captured reference.
+        ref(path).select(tpe)
+      case AppliedType(tycon, args) =>
+        AppliedTypeTree(treeify(TypeTree(tycon)), args.map(TypeTree))
+      case _ =>
+        tree
+
 }
 
 object PCPCheckAndHeal {

tests/pos-macros/i12440.scala

@@ -0,0 +1,21 @@
+import scala.quoted.*
+
+trait Mirror:
+  type ElemTypes <: Tuple
+
+class Eq:
+
+  def test1(using Quotes): Unit = '{
+    val m: Mirror = ???
+    ${ summonType[m.ElemTypes]; ??? }
+    ${ summonType[List[m.ElemTypes]]; ??? }
+  }
+
+  def test2(using Quotes): Unit = '{
+    val m: Mirror = ???
+    type ET = m.ElemTypes
+    ${ summonType[ET]; ??? }
+    ${ summonType[List[ET]]; ??? }
+  }
+
+  def summonType[X](using Type[X]) = ???

tests/pos-macros/i8100.scala

@@ -14,8 +14,8 @@ def f[T: Type](using Quotes) =
         ${ g[m.E](using Type.of[ME]) }
         ${ g[ME](using Type.of[m.E]) }
         ${ g[m.E](using Type.of[m.E]) }
-        // ${ g[ME] } // FIXME: issue seems to be in PickleQuotes
-        // ${ g[m.E] } // FIXME: issue seems to be in PickleQuotes
+        ${ g[ME] }
+        ${ g[m.E] }
       }
 
-def g[T](using Type[T]) = ???
+def g[T](using Type[T]) = ???