don't try to complete scala 2 macro before the constructor (and its type params) have been completed

Author: johnduffell

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -1030,7 +1030,7 @@ object SymDenotations {
 
     /** Is this a Scala 2 macro defined */
     final def isScala2MacroInScala3(using Context): Boolean =
-      is(Macro, butNot = Inline) && is(Erased)
+      is(Macro, butNot = Inline) && flagsUNSAFE.is(Erased) // flag is set initially for macros - we check if it's a scala 2 macro before completing the type constructor so do not force the info to check the flag
       // Consider the macros of StringContext as plain Scala 2 macros when
       // compiling the standard library with Dotty.
       // This should be removed on Scala 3.x