Add check for parents in Quotes (#i19842)

Author: hamzaremmal

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -253,6 +253,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
         (cdef.name.toString, cdef.constructor, cdef.parents, cdef.self, rhs.body)
 
       def module(module: Symbol, parents: List[Tree /* Term | TypeTree */], body: List[Statement]): (ValDef, ClassDef) = {
+        xCheckMacroAssert(parents.nonEmpty && !parents.head.tpe.dealias.classSymbol.is(dotc.core.Flags.Trait), "First parent must be a class")
         val cls = module.moduleClass
         val clsDef = ClassDef(cls, parents, body)
         val newCls = Apply(Select(New(TypeIdent(cls)), cls.primaryConstructor), Nil)

tests/neg-macros/i19842.check

@@ -0,0 +1,14 @@
+-- Error: tests/neg-macros/i19842/Test.scala:9:50 ----------------------------------------------------------------------
+9 |@main def Test = summon[Serializer[ValidationCls]] // error
+  |                                                  ^
+  |                                                  Exception occurred while executing macro expansion.
+  |                                                  java.lang.AssertionError: First parent must be a class
+  |                                                  	at Macros$.makeSerializer(Macro.scala:24)
+  |
+  |---------------------------------------------------------------------------------------------------------------------
+  |Inline stack trace
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |This location contains code that was inlined from Test.scala:5
+5 |    implicit inline def implicitMakeSerializer[T]: Serializer[T] = ${ Macros.makeSerializer[T] }
+  |                                                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   ---------------------------------------------------------------------------------------------------------------------

tests/neg-macros/i19842/Macro.scala

@@ -0,0 +1,28 @@
+
+import scala.annotation.{experimental, targetName}
+import scala.quoted.*
+import scala.util.Try
+
+object Macros {
+  def makeSerializer[T: Type](using Quotes): Expr[Serializer[T]] = {
+    import quotes.reflect.*
+
+    val tpe: TypeRepr = TypeRepr.of[T]
+    val name: String = Symbol.freshName("objectSerializer")
+
+    val modSym: Symbol = Symbol.newModule(
+      Symbol.spliceOwner,
+      name,
+      Flags.Implicit,
+      Flags.EmptyFlags,
+      List(TypeRepr.of[Object], TypeRepr.of[Serializer[T]]),
+      _ => Nil,
+      Symbol.noSymbol
+    )
+
+    val (modValDef: ValDef, modClassDef: ClassDef) =
+      ClassDef.module(modSym, List(TypeTree.of[Serializer[T]]), Nil)
+
+    Block(List(modValDef, modClassDef), Ref(modSym)).asExprOf[Serializer[T]]
+  }
+}

tests/neg-macros/i19842/Test.scala

@@ -0,0 +1,9 @@
+
+trait Serializer[@specialized T]
+
+object Serializer:
+    implicit inline def implicitMakeSerializer[T]: Serializer[T] = ${ Macros.makeSerializer[T] }
+
+case class ValidationCls(string: String)
+
+@main def Test = summon[Serializer[ValidationCls]] // error