Fix #10098: Handle inheritance for implicitNotFound annotation

Author: prolativ

compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala

@@ -250,7 +250,7 @@ class ImplicitSearchError(
    */
   private def userDefinedMsg(sym: Symbol, cls: Symbol) = for {
     ann <- sym.getAnnotation(cls)
-    Trees.Literal(Constant(msg: String)) <- ann.argument(0)
+    msg <- ann.argumentConstantString(0)
   } yield msg
 
   private def location(preposition: String) = if (where.isEmpty) "" else s" $preposition $where"
@@ -313,7 +313,7 @@ class ImplicitSearchError(
    *
    *  def foo(implicit @annotation.implicitNotFound("Foo is missing") foo: Foo): Any = ???
    */
-  private def userDefinedImplicitNotFoundParamMessage = paramSymWithMethodCallTree.flatMap { (sym, applTree) =>
+  private def userDefinedImplicitNotFoundParamMessage: Option[String] = paramSymWithMethodCallTree.flatMap { (sym, applTree) =>
     userDefinedMsg(sym, defn.ImplicitNotFoundAnnot).map { rawMsg =>
       val (fn, targs, _) = tpd.decomposeCall(applTree)
       val methodOwner = fn.symbol.owner
@@ -332,8 +332,12 @@ class ImplicitSearchError(
    *
    *  def foo(implicit foo: Foo): Any = ???
    */
-  private def userDefinedImplicitNotFoundTypeMessage =
-    val classSym = pt.classSymbol
+  private def userDefinedImplicitNotFoundTypeMessage: Option[String] =
+    pt.baseClasses.iterator
+      .map(userDefinedImplicitNotFoundTypeMessage(_))
+      .find(_.isDefined).flatten
+
+  private def userDefinedImplicitNotFoundTypeMessage(classSym: ClassSymbol): Option[String] =
     userDefinedMsg(classSym, defn.ImplicitNotFoundAnnot).map { rawMsg =>
       val substituteType = (_: Type).asSeenFrom(pt, classSym)
       formatAnnotationMessage(rawMsg, classSym, substituteType)

tests/neg/i10098.check

@@ -0,0 +1,16 @@
+-- Error: tests/neg/i10098.scala:20:32 ---------------------------------------------------------------------------------
+20 |  implicitly[Bar12[Int, String]] // error
+   |                                ^
+   |                                There's no Foo2[String, Int]
+-- Error: tests/neg/i10098.scala:21:32 ---------------------------------------------------------------------------------
+21 |  implicitly[Bar21[Int, String]] // error
+   |                                ^
+   |                                There's no Foo1[String, Int]
+-- Error: tests/neg/i10098.scala:22:32 ---------------------------------------------------------------------------------
+22 |  implicitly[Baz12[Int, String]] // error
+   |                                ^
+   |                                There's no Baz12[Int, String]
+-- Error: tests/neg/i10098.scala:23:32 ---------------------------------------------------------------------------------
+23 |  implicitly[Baz21[Int, String]] // error
+   |                                ^
+   |                                There's no Baz21[Int, String]

tests/neg/i10098.scala

@@ -0,0 +1,24 @@
+import annotation.implicitNotFound
+
+@implicitNotFound("There's no Foo1[${A}, ${B}]")
+trait Foo1[A, B]
+
+@implicitNotFound("There's no Foo2[${A}, ${B}]")
+trait Foo2[A, B]
+
+trait Bar12[C, D] extends Foo1[D, C] with Foo2[D, C]
+
+trait Bar21[C, D] extends Foo2[D, C] with Foo1[D, C]
+
+@implicitNotFound("There's no Baz12[${C}, ${D}]")
+trait Baz12[C, D] extends Foo1[D, C] with Foo2[D, C]
+
+@implicitNotFound("There's no Baz21[${C}, ${D}]")
+trait Baz21[C, D] extends Foo2[D, C] with Foo1[D, C]
+
+object Test {
+  implicitly[Bar12[Int, String]] // error
+  implicitly[Bar21[Int, String]] // error
+  implicitly[Baz12[Int, String]] // error
+  implicitly[Baz21[Int, String]] // error
+}

tests/neg/i4986c.scala

@@ -16,15 +16,15 @@ class Outer[A] {
 
 trait X$Y
 
-@implicitNotFound("There's no U[${X}, ${Y}, ${Z}]")
+@implicitNotFound(msg = "There's no U[${X}, ${Y}, ${Z}]")
 trait U[X, Y[_], Z[_, ZZ]] {
   class I[R] {
     def m[S](implicit @implicitNotFound("${X}; ${Y}; ${ Z }; ${R}; ${S}; ${XX}") i: Int) = ???
   }
 }
 
 class Test[A] {
-  def f(implicit @implicitNotFound("Missing X$Y for Test[${A}]") xy: X$Y) = ???
+  def f(implicit @implicitNotFound(msg = "Missing X$Y for Test[${A}]") xy: X$Y) = ???
   def g[B: Outer] = ???
   def h[B](implicit outer: Outer[B]) = ???
   def i[B](implicit @implicitNotFound("Missing implicit outer param of type Outer[${B}] for Test[${A}]") outer: Outer[B]) = ???