[PATCH] ada/41383: Return correct time for unset event

[Samuel Tardieu <sam at rfc1149 dot net>]

Calling Cancel_Handler clears an event (RM D.15(17/2)). The
time of an unset event as returned by Time_Of_Event must be
Ada.Real_Time.Time_First (RM D.15(18/2)).

The attached test program must execute without error.

The patch is trivial.

    gcc/ada/
	PR ada/41383
	* a-rttiev.adb (Time_Of_Event): Return Time_First for unset event.

    gcc/testsuite/
	PR ada/41383
	* gnat.dg/timer_cancel.adb: New test.

Tested on x86_64-unknown-linux-gnu. Ok for trunk?

---
 gcc/ada/a-rttiev.adb                   |    8 ++++++-
 gcc/testsuite/gnat.dg/timer_cancel.adb |   38 ++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletions(-)

diff --git a/gcc/ada/a-rttiev.adb b/gcc/ada/a-rttiev.adb
index 2068c78..0b86066 100644
--- a/gcc/ada/a-rttiev.adb
+++ b/gcc/ada/a-rttiev.adb
@@ -332,7 +332,13 @@ package body Ada.Real_Time.Timing_Events is
 
    function Time_Of_Event (Event : Timing_Event) return Time is
    begin
-      return Event.Timeout;
+      --  RM D.15(18/2): Time_First must be returned in the event is not set
+
+      if Event.Handler = null then
+         return Time_First;
+      else
+         return Event.Timeout;
+      end if;
    end Time_Of_Event;
 
    --------------
diff --git a/gcc/testsuite/gnat.dg/timer_cancel.adb b/gcc/testsuite/gnat.dg/timer_cancel.adb
new file mode 100644
index 0000000..c300b47
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/timer_cancel.adb
@@ -0,0 +1,38 @@
+-- { dg-do run }
+
+with Ada.Real_Time.Timing_Events;
+use Ada.Real_Time, Ada.Real_Time.Timing_Events;
+
+procedure Timer_Cancel is
+
+   E : Timing_Event;
+   C : Boolean;
+
+   protected Dummy is
+      procedure Trigger (Event : in out Timing_Event);
+   end Dummy;
+
+   protected body Dummy is
+      procedure Trigger (Event : in out Timing_Event) is
+      begin
+         null;
+      end Trigger;
+   end Dummy;
+
+begin
+   Set_Handler (E, Time_Last, Dummy.Trigger'Unrestricted_Access);
+
+   if Time_Of_Event (E) /= Time_Last then
+      raise Program_Error with "Event time not set correctly";
+   end if;
+
+   Cancel_Handler (E, C);
+
+   if not C then
+      raise Program_Error with "Event triggered already";
+   end if;
+
+   if Time_Of_Event (E) /= Time_First then
+      raise Program_Error with "Event time not reset correctly";
+   end if;
+end Timer_Cancel;
-- 
tg: (47c3d42..) t/cancel-time-event (depends on: origin/trunk)