Fix references to class members defined in quotes

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

@@ -208,6 +208,14 @@ class Splicing extends MacroTransform:
 
     override def transform(tree: tpd.Tree)(using Context): tpd.Tree =
       tree match
+        case tree: Select if tree.isTerm && isCaptured(tree.symbol) =>
+          tree.symbol.allOverriddenSymbols.find(sym => !isCaptured(sym.owner)) match
+            case Some(sym) =>
+              // virtualize call on overridden symbol that is not defined in a non static class
+              transform(tree.qualifier.select(sym))
+            case _ =>
+              report.error(em"Can not use reference to staged local ${tree.symbol} defined in an outer quote.\n\nThis can work if ${tree.symbol.owner} would extend a top level interface that defines ${tree.symbol}.", tree)
+              tree
         case tree: RefTree =>
           if tree.isTerm then
             if isCaptured(tree.symbol) then

tests/neg-macros/i17103.scala

@@ -0,0 +1,16 @@
+import scala.quoted.*
+
+def test(using Quotes): Expr[Unit] =
+  '{
+    trait C:
+      def d: Int
+    val c: C = ???
+    ${
+      val expr = '{
+        val cRef: c.type = ???
+        cRef.d // error
+        ()
+      }
+      expr
+    }
+  }

tests/pos-macros/i17103a.scala

@@ -0,0 +1,21 @@
+import scala.quoted.*
+
+trait C0:
+  def d: Int
+
+def test(using Quotes): Expr[Unit] =
+  '{
+    trait C1 extends C0:
+      def d: Int
+    trait C extends C1:
+      def d: Int
+    val c: C = ???
+    ${
+      val expr = '{
+        val cRef: C = ???
+        cRef.d // calls C0.d
+        ()
+      }
+      expr
+    }
+  }

tests/pos-macros/i17103b.scala

@@ -0,0 +1,21 @@
+import scala.quoted.*
+
+trait C0:
+  def d: Int
+
+def test(using Quotes): Expr[Unit] =
+  '{
+    trait C1 extends C0:
+      def d: Int
+    trait C extends C1:
+      def d: Int
+    val c: C = ???
+    ${
+      val expr = '{
+        val cRef: c.type = ???
+        cRef.d // calls C0.d
+        ()
+      }
+      expr
+    }
+  }

tests/pos-macros/i7405b.scala

@@ -3,7 +3,7 @@ import scala.quoted.*
 class Foo {
   def f(using Quotes): Expr[Any] = {
     '{
-      trait X {
+      trait X extends A {
         type Y
         def y: Y = ???
       }
@@ -17,3 +17,7 @@ class Foo {
     }
   }
 }
+
+trait A:
+  type Y
+  def y: Y = ???