# HG changeset patch
# User wenzelm
# Date 1509537961 -3600
# Node ID f65fc869e83589b1c0b12d2f72007c6e2010ffa1
# Parent  43b2aac6053c65f71144300c834f8bf63c52f333
no heap sharing for empty session (e.g. HOL-ODE);

diff -r 43b2aac6053c -r f65fc869e835 src/Pure/Tools/build.scala
--- a/src/Pure/Tools/build.scala	Wed Nov 01 12:31:53 2017 +0100
+++ b/src/Pure/Tools/build.scala	Wed Nov 01 13:06:01 2017 +0100
@@ -227,8 +227,8 @@
             ("ISABELLE_ML_DEBUGGER" -> options.bool("ML_debugger").toString)
 
         def save_heap: String =
-          "ML_Heap.share_common_data (); ML_Heap.save_child " +
-            ML_Syntax.print_string_bytes(File.platform_path(output))
+          (if (info.theories.isEmpty) "" else "ML_Heap.share_common_data (); ") +
+            "ML_Heap.save_child " + ML_Syntax.print_string_bytes(File.platform_path(output))
 
         if (pide && !Sessions.is_pure(name)) {
           val resources = new Resources(deps(parent))