Add passTime to DAML Script (#7269)

I’ve also removed the restriction to only support going forward since
scenarios don’t have that restriction and it seems potentially useful
for tests.

factored out from #7264

changelog_begin

- [DAML Script] Add `passTime` helper to advance the time by the
  given interval.

- [DAML Script] In DAML Studio, you can now set the time to the
  past. This is not supported when running against a ledger.

changelog_end

compiler/damlc/tests/src/DA/Test/ScriptService.hs

@@ -349,6 +349,7 @@ main =
                       "import Daml.Script",
                       "import DA.Date",
                       "import DA.Time",
+                      "import DA.Assert",
                       "template T",
                       "  with",
                       "    p : Party",
@@ -368,7 +369,16 @@ main =
                       "  t0 <- submit p $ exerciseCmd cid GetTime",
                       "  setTime (time (date 2000 Feb 2) 0 1 2)",
                       "  t1 <- submit p $ exerciseCmd cid GetTime",
-                      "  pure (t0, t1)"
+                      "  pure (t0, t1)",
+                      "testPassTime = do",
+                      "  p <- allocateParty \"p\"",
+                      "  t0 <- getTime",
+                      "  passTime (days 1)",
+                      "  t1 <- getTime",
+                      "  t1 === addRelTime t0 (days 1)",
+                      "  cid <- submit p $ createCmd (T p)",
+                      "  passTime (days (-1))",
+                      "  submit p $ exerciseCmd cid Archive"
                     ]
                 expectScriptSuccess rs (vr "testTime") $ \r ->
                     matchRegex r $
@@ -385,7 +395,10 @@ main =
                           "  DA\\.Types:Tuple2@[a-z0-9]+ with",
                           "    _1 = 1970-01-01T00:00:00Z; _2 = 2000-02-02T00:01:02Z",
                           ""
-                        ],
+                        ]
+                expectScriptFailure rs (vr "testPassTime") $ \r ->
+                    matchRegex r "Attempt to fetch or exercise a contract not yet effective"
+            ,
               testCase "partyManagement" $ do
                 rs <-
                   runScripts

daml-script/daml/Daml/Script.daml

@@ -24,6 +24,7 @@ module Daml.Script
   , archiveCmd
   , getTime
   , setTime
+  , passTime
   , sleep
   , script
   ) where
@@ -114,12 +115,27 @@ data SetTimePayload a = SetTimePayload
 --
 -- This is only supported in static time mode when running over the gRPC API.
 --
--- Note that the time service does not support going backwards in time.
+-- Note that the ledger time service does not support going backwards in time.
+-- However, you can go back in time in DAML Studio.
 setTime : Time -> Script ()
 setTime time = lift $ Free $ SetTime $ SetTimePayload with
   time
   continue = pure
 
+-- | Advance ledger time by the given interval.
+--
+-- Only supported in static time mode when running over the gRPC API
+-- and in DAML Studio. Note that this is not an atomic operation over the
+-- gRPC API so no other clients should try to change time while this is
+-- running.
+--
+-- Note that the ledger time service does not support going backwards in time.
+-- However, you can go back in time in DAML Studio.
+passTime : RelTime -> Script ()
+passTime rt = do
+  t <- getTime
+  setTime (addRelTime t rt)
+
 data AllocateParty a = AllocateParty
   { displayName : Text
   , idHint : Text

daml-script/runner/src/main/scala/com/digitalasset/daml/lf/engine/script/LedgerInteraction.scala

@@ -547,13 +547,10 @@ class IdeClient(val compiledPackages: CompiledPackages) extends ScriptLedgerClie
       esf: ExecutionSequencerFactory,
       mat: Materializer): Future[Unit] = {
     val diff = time.micros - scenarioRunner.ledger.currentTime.micros
-    // ScenarioLedger only provides pass, so we have to check the difference.
-    if (diff < 0) {
-      Future.failed(new RuntimeException("Time cannot be set backwards"))
-    } else {
-      scenarioRunner.ledger = scenarioRunner.ledger.passTime(diff)
-      Future.unit
-    }
+    // ScenarioLedger only provides pass, so we have to calculate the diff.
+    // Note that ScenarioLedger supports going backwards in time.
+    scenarioRunner.ledger = scenarioRunner.ledger.passTime(diff)
+    Future.unit
   }
 }