save heap more directly;

--- a/src/Pure/PIDE/session.ML	Mon Feb 29 15:39:17 2016 +0100
+++ b/src/Pure/PIDE/session.ML	Mon Feb 29 16:12:47 2016 +0100
@@ -13,7 +13,6 @@
     (Path.T * Path.T) list -> Path.T -> string -> string * string -> bool -> unit
   val shutdown: unit -> unit
   val finish: unit -> unit
-  val save: string -> unit
   val protocol_handler: string -> unit
   val init_protocol_handlers: unit -> unit
 end;
@@ -75,11 +74,6 @@
       (Thy_Info.get_names ()) Keyword.empty_keywords;
   session_finished := true);
 
-fun save heap =
- (shutdown ();
-  ML_Heap.share_common_data ();
-  ML_Heap.save_state heap);
-
 
 
 (** protocol handlers **)

--- a/src/Pure/Tools/build.ML	Mon Feb 29 15:39:17 2016 +0100
+++ b/src/Pure/Tools/build.ML	Mon Feb 29 16:12:47 2016 +0100
@@ -124,15 +124,16 @@
     let
       val _ = SHA1_Samples.test ();
 
-      val (symbol_codes, (command_timings, (do_output, (options, (verbose, (browser_info,
+      val (symbol_codes, (command_timings, (output, (options, (verbose, (browser_info,
           (document_files, (graph_file, (parent_name, (chapter, (name, theories))))))))))) =
         File.read (Path.explode args_file) |> YXML.parse_body |>
           let open XML.Decode in
-            pair (list (pair string int)) (pair (list properties) (pair bool (pair Options.decode
+            pair (list (pair string int)) (pair (list properties) (pair string (pair Options.decode
               (pair bool (pair string (pair (list (pair string string)) (pair string
                 (pair string (pair string (pair string
                 ((list (pair Options.decode (list (string #> rpair Position.none)))))))))))))))
           end;
+      val do_output = output <> "";
 
       val symbols = HTML.make_symbols symbol_codes;
       val _ = Options.set_default options;
@@ -165,7 +166,8 @@
       val _ = Par_Exn.release_all [res1, res2];
 
       val _ = Options.reset_default ();
-      val _ = if do_output then () else exit 0;
+      val _ = Session.shutdown ();
+      val _ = if do_output then (ML_Heap.share_common_data (); ML_Heap.save_state output) else ();
     in () end);
 
 

--- a/src/Pure/Tools/build.scala	Mon Feb 29 15:39:17 2016 +0100
+++ b/src/Pure/Tools/build.scala	Mon Feb 29 16:12:47 2016 +0100
@@ -541,6 +541,7 @@
     browser_info: Path, session_graph: Graph_Display.Graph, command_timings: List[Properties.T])
   {
     def output_path: Option[Path] = if (do_output) Some(output) else None
+    def output_standard_path: String = if (do_output) File.standard_path(output) else ""
 
     private val parent = info.parent.getOrElse("")
 
@@ -555,25 +556,25 @@
         {
           val theories = info.theories.map(x => (x._2, x._3))
           import XML.Encode._
-          pair(list(pair(string, int)), pair(list(properties), pair(bool, pair(Options.encode,
+          pair(list(pair(string, int)), pair(list(properties), pair(string, pair(Options.encode,
             pair(bool, pair(Path.encode, pair(list(pair(Path.encode, Path.encode)), pair(string,
             pair(string, pair(string, pair(string,
             list(pair(Options.encode, list(Path.encode))))))))))))))(
-          (Symbol.codes, (command_timings, (do_output, (info.options,
+          (Symbol.codes, (command_timings, (output_standard_path, (info.options,
             (verbose, (browser_info, (info.document_files, (File.standard_path(graph_file),
             (parent, (info.chapter, (name,
             theories))))))))))))
         }))
 
     private val env =
-      Map("INPUT" -> parent, "TARGET" -> name, "OUTPUT" -> File.standard_path(output),
+      Map("INPUT" -> parent, "TARGET" -> name, "OUTPUT" -> output_standard_path,
         (if (is_pure(name)) "ISABELLE_PROCESS_OPTIONS" else "ARGS_FILE") ->
           File.standard_path(args_file))
 
     private val script =
       if (is_pure(name)) {
         if (do_output) "./build " + name + " \"$OUTPUT\""
-        else """ rm -f "$OUTPUT"; ./build """ + name
+        else "./build " + name
       }
       else {
         """
@@ -581,7 +582,7 @@
         """ +
           (if (do_output)
             """
-            "$ISABELLE_PROCESS" -e "Build.build \"$ARGS_FILE\";" -q -w "$INPUT" "$OUTPUT"
+            "$ISABELLE_PROCESS" -e "Build.build \"$ARGS_FILE\";" -r -q "$INPUT" && chmod -w "$OUTPUT"
             """
           else
             """

--- a/src/Pure/build	Mon Feb 29 15:39:17 2016 +0100
+++ b/src/Pure/build	Mon Feb 29 16:12:47 2016 +0100
@@ -64,11 +64,13 @@
       -e "use \"$COMPAT\" handle _ => OS.Process.exit OS.Process.failure;" \
       -q RAW_ML_SYSTEM
   else
+    rm -f "$OUTPUT"
     "$ISABELLE_PROCESS" \
       -e "use \"$COMPAT\" handle _ => OS.Process.exit OS.Process.failure;" \
       -e "structure Isar = struct fun main () = () end;" \
       -e "ml_prompts \"ML> \" \"ML# \";" \
-      -q -w RAW_ML_SYSTEM "$OUTPUT"
+      -e "ML_Heap.share_common_data (); ML_Heap.save_state \"$OUTPUT\";" \
+      -q RAW_ML_SYSTEM && chmod -w "$OUTPUT"
   fi
 else
   if [ -z "$OUTPUT" ]; then
@@ -76,12 +78,15 @@
       -e "(use \"$COMPAT\"; use \"ROOT.ML\") handle _ => OS.Process.exit OS.Process.failure;" \
       -q RAW_ML_SYSTEM
   else
+    rm -f "$OUTPUT"
     "$ISABELLE_PROCESS" \
       -e "(use \"$COMPAT\"; use \"ROOT.ML\") handle _ => OS.Process.exit OS.Process.failure;" \
       -e "ml_prompts \"ML> \" \"ML# \";" \
       -e "Command_Line.tool0 Session.finish;" \
       -e "Options.reset_default ();" \
-      -q -w RAW_ML_SYSTEM "$OUTPUT"
+      -e "Session.shutdown ();" \
+      -e "ML_Heap.share_common_data (); ML_Heap.save_state \"$OUTPUT\";" \
+      -q RAW_ML_SYSTEM && chmod -w "$OUTPUT"
   fi
 fi