diff -r 88dfbc382a3d -r 48ff625687f5 src/Pure/Isar/specification.ML
--- a/src/Pure/Isar/specification.ML	Fri Apr 03 12:45:14 2020 +0200
+++ b/src/Pure/Isar/specification.ML	Fri Apr 03 13:51:56 2020 +0200
@@ -323,7 +323,7 @@
 fun gen_alias decl check (b, arg) lthy =
   let
     val (c, reports) = check {proper = true, strict = false} lthy arg;
-    val _ = Position.reports reports;
+    val _ = Context_Position.reports lthy reports;
   in decl b c lthy end;
 
 val alias =