# HG changeset patch
# User Adam Chlipala <adam@chlipala.net>
# Date 1335963379 14400
# Node ID 78d7cc9c9b185492574c1916bf548b353af15c08
# Parent  7ec8dab190a78680f4060734d9d38f9cb1998065
Don't modify the module cache after elaboration failures

diff -r 7ec8dab190a7 -r 78d7cc9c9b18 src/elaborate.sml
--- a/src/elaborate.sml	Wed May 02 08:34:50 2012 -0400
+++ b/src/elaborate.sml	Wed May 02 08:56:19 2012 -0400
@@ -4461,6 +4461,8 @@
 
 fun elabFile basis basis_tm topStr topSgn top_tm env file =
     let
+        val () = ModDb.snapshot ()
+
         val () = mayDelay := true
         val () = delayedUnifs := []
         val () = delayedExhaustives := []
@@ -4788,6 +4790,11 @@
             end
         else
             ();
+
+        if ErrorMsg.anyErrors () then
+            ModDb.revert ()
+        else
+            ();
         
         (L'.DFfiStr ("Basis", basis_n, sgn), ErrorMsg.dummySpan)
         :: ds
diff -r 7ec8dab190a7 -r 78d7cc9c9b18 src/mod_db.sig
--- a/src/mod_db.sig	Wed May 02 08:34:50 2012 -0400
+++ b/src/mod_db.sig	Wed May 02 08:56:19 2012 -0400
@@ -35,4 +35,8 @@
      * We might invalidate other declarations that depend on this one, if the timestamp has changed. *)
 
     val lookup : Source.decl -> Elab.decl option
+
+    (* Allow undoing to snapshots after failed compilations. *)
+    val snapshot : unit -> unit
+    val revert : unit -> unit
 end
diff -r 7ec8dab190a7 -r 78d7cc9c9b18 src/mod_db.sml
--- a/src/mod_db.sml	Wed May 02 08:34:50 2012 -0400
+++ b/src/mod_db.sml	Wed May 02 08:56:19 2012 -0400
@@ -141,4 +141,10 @@
                  NONE)
       | _ => NONE
 
+val byNameBackup = ref (!byName)
+val byIdBackup = ref (!byId)
+
+fun snapshot () = (byNameBackup := !byName; byIdBackup := !byId)
+fun revert () = (byName := !byNameBackup; byId := !byIdBackup)
+
 end
diff -r 7ec8dab190a7 -r 78d7cc9c9b18 tests/baddep.urp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/baddep.urp	Wed May 02 08:56:19 2012 -0400
@@ -0,0 +1,2 @@
+baddep1
+baddep2
diff -r 7ec8dab190a7 -r 78d7cc9c9b18 tests/baddep1.ur
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/baddep1.ur	Wed May 02 08:56:19 2012 -0400
@@ -0,0 +1,1 @@
+val x : int = "hi"
diff -r 7ec8dab190a7 -r 78d7cc9c9b18 tests/baddep2.ur
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/baddep2.ur	Wed May 02 08:56:19 2012 -0400
@@ -0,0 +1,1 @@
+fun main () : transaction page = return <xml/>