Fix #9020: Handle spliced types in parents

compiler/src/dotty/tools/dotc/core/quoted/PickledQuotes.scala

@@ -139,15 +139,15 @@ object PickledQuotes {
             (tdef.symbol, tree.tpe)
         }.toMap
         class ReplaceSplicedTyped extends TypeMap() {
-          override def apply(tp: Type): Type = {
-            val tp1 = tp match {
-              case tp: TypeRef =>
-                typeSpliceMap.get(tp.symbol) match
-                  case Some(t) if tp.typeSymbol.hasAnnotation(defn.InternalQuoted_QuoteTypeTagAnnot) => t
-                  case _ => tp
-              case _ => tp
-            }
-            mapOver(tp1)
+          override def apply(tp: Type): Type = tp match {
+            case tp: ClassInfo =>
+              tp.derivedClassInfo(classParents = tp.classParents.map(apply))
+            case tp: TypeRef =>
+              typeSpliceMap.get(tp.symbol) match
+                case Some(t) if tp.typeSymbol.hasAnnotation(defn.InternalQuoted_QuoteTypeTagAnnot) => mapOver(t)
+                case _ => mapOver(tp)
+            case _ =>
+              mapOver(tp)
           }
         }
         val expansion2 = new TreeTypeMap(new ReplaceSplicedTyped).transform(expr1)

tests/pos-macros/i9020-a/Macro_1.scala

@@ -0,0 +1,15 @@
+trait Show[T] {
+  def show(t: T): String
+}
+
+object Show {
+  inline def deriveWithMacro[T]: Show[T] = ${ impl[T] }
+
+  import quoted._
+  def impl[T](using ctx: QuoteContext, tpe: Type[T]): Expr[Show[T]] =
+    '{
+      new Show[T] {
+        def show(t: T): String = "TODO"
+      }
+    }
+}

tests/pos-macros/i9020-a/Test_2.scala

@@ -0,0 +1,5 @@
+case class Foo(x: String)
+
+object Bar {
+  println(Show.deriveWithMacro[Foo].show(Foo("")))
+}

tests/pos-macros/i9020-b/Macro_1.scala

@@ -0,0 +1,15 @@
+trait Show[T] {
+  def show(t: T): String
+}
+
+object Show {
+  inline def deriveWithMacro[T]: Show[T] = ${ impl[T] }
+
+  import quoted._
+  def impl[T](using ctx: QuoteContext, tpe: Type[T]): Expr[Show[T]] =
+    '{
+      new Show[$tpe] {
+        def show(t: $tpe): String = "TODO"
+      }
+    }
+}

tests/pos-macros/i9020-b/Test_2.scala

@@ -0,0 +1,5 @@
+case class Foo(x: String)
+
+object Bar {
+  println(Show.deriveWithMacro[Foo].show(Foo("")))
+}