Merge pull request #6550 from dotty-staging/fix-scala2-maco

Improve Scala 2 macro error handling

Author: smarter

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

@@ -2809,8 +2809,10 @@ class Typer extends Namer
       }
       else if (tree.symbol.isScala2Macro) {
         if (ctx.settings.XignoreScala2Macros.value) {
-          ctx.warning("Scala 2 macro cannot be used in Dotty, this call will crash at runtime. See http://dotty.epfl.ch/docs/reference/dropped-features/macros.html", tree.sourcePos)
-          Throw(New(defn.MatchErrorType, Literal(Constant(s"Reached unexpanded Scala 2 macro call to ${tree.symbol.showFullName} compiled with -Xignore-scala2-macros.")) :: Nil)).withSpan(tree.span)
+          ctx.warning("Scala 2 macro cannot be used in Dotty, this call will crash at runtime. See http://dotty.epfl.ch/docs/reference/dropped-features/macros.html", tree.sourcePos.startPos)
+          Throw(New(defn.MatchErrorType, Literal(Constant(s"Reached unexpanded Scala 2 macro call to ${tree.symbol.showFullName} compiled with -Xignore-scala2-macros.")) :: Nil))
+            .withType(tree.tpe)
+            .withSpan(tree.span)
         } else if (tree.symbol eq defn.StringContext_f) {
           // As scala.StringContext.f is defined in the standard library which
           // we currently do not bootstrap we cannot implement the macro the library.
@@ -2821,7 +2823,9 @@ class Typer extends Namer
           val newCall = ref(defn.InternalStringContextMacroModule_f).appliedTo(sc).appliedToArgs(args)
           readaptSimplified(Inliner.inlineCall(newCall))
         } else {
-          ctx.error("Scala 2 macro cannot be used in Dotty. See http://dotty.epfl.ch/docs/reference/dropped-features/macros.html", tree.sourcePos)
+          ctx.error(
+            """Scala 2 macro cannot be used in Dotty. See http://dotty.epfl.ch/docs/reference/dropped-features/macros.html\n"
+              |To turn this error into a warning, pass -Xignore-scala2-macros to the compiler""".stripMargin, tree.sourcePos.startPos)
           tree
         }
       }