Fix #7650: Don't load toplevel definitions in the empty package

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

@@ -2122,11 +2122,20 @@ object SymDenotations {
         case pcls :: pobjs1 =>
           if (pcls.isCompleting) recur(pobjs1, acc)
           else {
-            // A package object inherits members from `Any` and `Object` which
-            // should not be accessible from the package prefix.
             val pmembers = pcls.computeNPMembersNamed(name).filterWithPredicate { d =>
+              // Drop members of `Any` and `Object`, as well as top-level definitions
+              // in the empty package that are not defined in the current run.
               val owner = d.symbol.maybeOwner
-              (owner ne defn.AnyClass) && (owner ne defn.ObjectClass)
+              (owner ne defn.AnyClass)
+              && (owner ne defn.ObjectClass)
+              && (
+                (symbol ne defn.EmptyPackageClass)
+                || d.symbol.isDefinedInCurrentRun
+                || d.symbol.associatedFile == null
+                    // if a symbol does not have an associated file, assume it is defined
+                    // in the current run anyway. This typically happens for pickling and from
+                    // tasty tests that generate a fresh symbol and then re-use it in the next run.
+              )
             }
             recur(pobjs1, acc.union(pmembers))
           }

compiler/test/dotc/run-test-pickling.blacklist

@@ -14,6 +14,7 @@ typeclass-derivation2d.scala
 typeclass-derivation3.scala
 derive-generic.scala
 mixin-forwarder-overload
+toplevel-defs
 t8905
 t10889
 macros-in-same-project1

tests/pos/i7650/Test_1.scala

@@ -0,0 +1 @@
+@main def Test() = println("hi")

tests/pos/i7650/Test_2.scala

@@ -0,0 +1 @@
+object Test