Do not propagate macro annotations to exported methods

[Cherry-picked 29deb05]

Author: nicolasstucki

Diff for: compiler/src/dotty/tools/dotc/typer/Namer.scala

@@ -1254,6 +1254,7 @@ class Namer { typer: Typer =>
           forwarder.addAnnotations(sym.annotations.filterConserve { annot =>
             annot.symbol != defn.BodyAnnot
             && annot.symbol != defn.TailrecAnnot
+            && !annot.symbol.derivesFrom(defn.MacroAnnotationClass)
           })
 
           if forwarder.isType then

Diff for: tests/run-macros/annot-export/Macro_1.scala

@@ -0,0 +1,13 @@
+import scala.annotation.{experimental, MacroAnnotation}
+import scala.quoted._
+import scala.collection.mutable.Map
+
+@experimental
+class returnClassName extends MacroAnnotation {
+  def transform(using Quotes)(tree: quotes.reflect.Definition): List[quotes.reflect.Definition] =
+    import quotes.reflect._
+    tree match
+      case DefDef(name, params, tpt, _) =>
+        val rhs = Literal(StringConstant(Symbol.spliceOwner.name.stripSuffix("$")))
+        List(DefDef.copy(tree)(name, params, tpt, Some(rhs)))
+}

Diff for: tests/run-macros/annot-export/Test_2.scala

@@ -0,0 +1,10 @@
+object Bar:
+  @returnClassName
+  def f(): String = ??? // def f(): String = "Bar"
+
+object Baz:
+  export Bar.f // def f(): String = Bar.f(n)
+
+@main def Test =
+  assert(Bar.f() == "Bar")
+  assert(Baz.f() == "Bar")