[multiple changes]

2017-05-02  Bob Duff  <duff@adacore.com>

	* s-taprop-linux.adb (Prio_To_Linux_Prio): New function to correctly
	compute the linux priority from the Ada priority. Call this everywhere
	required. In particular, the previous version was not doing this
	computation when setting the ceiling priority in various places. It
	was just converting to C.int, which results in a ceiling that is off
	by 1.

2017-05-02  Ed Schonberg  <schonberg@adacore.com>

	* sem_ch3.adb: Comment predicate inheritance.

From-SVN: r247473

3 files changed, 145 insertions, 120 deletions

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index dfe1102..0d53e03 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,16 @@
+2017-05-02  Bob Duff  <duff@adacore.com>
+
+	* s-taprop-linux.adb (Prio_To_Linux_Prio): New function to correctly
+	compute the linux priority from the Ada priority. Call this everywhere
+	required. In particular, the previous version was not doing this
+	computation when setting the ceiling priority in various places. It
+	was just converting to C.int, which results in a ceiling that is off
+	by 1.
+
+2017-05-02  Ed Schonberg  <schonberg@adacore.com>
+
+	* sem_ch3.adb: Comment predicate inheritance.
+
 2017-05-02  Tristan Gingold  <gingold@adacore.com>
 
 	* s-trasym.ads: Add comment.
diff --git a/gcc/ada/s-taprop-linux.adb b/gcc/ada/s-taprop-linux.adb
index bc49f68..1d829de 100644
--- a/gcc/ada/s-taprop-linux.adb
+++ b/gcc/ada/s-taprop-linux.adb
@@ -38,7 +38,7 @@ pragma Polling (Off);
 --  Turn off polling, we do not want ATC polling to take place during tasking
 --  operations. It causes infinite loops and other problems.
 
-with Interfaces.C;
+with Interfaces.C; use Interfaces; use type Interfaces.C.int;
 
 with System.Task_Info;
 with System.Tasking.Debug;
@@ -60,7 +60,6 @@ package body System.Task_Primitives.Operations is
 
    use System.Tasking.Debug;
    use System.Tasking;
-   use Interfaces.C;
    use System.OS_Interface;
    use System.Parameters;
    use System.OS_Primitives;
@@ -111,14 +110,6 @@ package body System.Task_Primitives.Operations is
    --  Constant to indicate that the thread identifier has not yet been
    --  initialized.
 
-   function geteuid return Integer;
-   pragma Import (C, geteuid, "geteuid");
-   pragma Warnings (Off, "non-static call not allowed in preelaborated unit");
-   Superuser : constant Boolean := geteuid = 0;
-   pragma Warnings (On, "non-static call not allowed in preelaborated unit");
-   --  True if we are running as 'root'. On Linux, ceiling priorities work only
-   --  in that case, so if this is False, we ignore Locking_Policy = 'C'.
-
    --------------------
    -- Local Packages --
    --------------------
@@ -170,17 +161,52 @@ package body System.Task_Primitives.Operations is
    procedure Abort_Handler (signo : Signal);
 
    function GNAT_pthread_condattr_setup
-     (attr : access pthread_condattr_t) return int;
-   pragma Import (C,
-     GNAT_pthread_condattr_setup, "__gnat_pthread_condattr_setup");
+     (attr : access pthread_condattr_t) return C.int;
+   pragma Import
+     (C, GNAT_pthread_condattr_setup, "__gnat_pthread_condattr_setup");
+
+   function Prio_To_Linux_Prio (Prio : Any_Priority) return C.int is
+     (C.int (Prio) + 1);
+   --  Convert Ada priority to Linux priority. Priorities are 1 .. 99 on
+   --  GNU/Linux, so we map 0 .. 98 to 1 .. 99.
+
+   function Get_Ceiling_Support return Boolean;
+   --  Get the value of the Ceiling_Support constant (see below).
+   --  ???For now, we're returning True only if running as superuser,
+   --  and ignore capabilities.
+
+   function Get_Ceiling_Support return Boolean is
+      Ceiling_Support : Boolean := False;
+   begin
+      if Locking_Policy = 'C' then
+         declare
+            function geteuid return Integer;
+            pragma Import (C, geteuid, "geteuid");
+            Superuser : constant Boolean := geteuid = 0;
+         begin
+            if Superuser then
+               Ceiling_Support := True;
+            end if;
+         end;
+      end if;
+
+      return Ceiling_Support;
+   end Get_Ceiling_Support;
+
+   pragma Warnings (Off, "non-static call not allowed in preelaborated unit");
+   Ceiling_Support : constant Boolean := Get_Ceiling_Support;
+   pragma Warnings (On, "non-static call not allowed in preelaborated unit");
+   --  True if the locking policy is Ceiling_Locking, and the current process
+   --  has permission to use this policy. The process has permission if it is
+   --  running as 'root', or if the capability was set by the setcap command,
+   --  as in "sudo /sbin/setcap cap_sys_nice=ep exe_file". If it doesn't have
+   --  permission, then a request for Ceiling_Locking is ignored.
 
    type RTS_Lock_Ptr is not null access all RTS_Lock;
 
-   function Init_Mutex
-     (L : RTS_Lock_Ptr; Prio : Any_Priority)
-     return Interfaces.C.int;
-   --  Initialize the mutex L. If the locking policy is Ceiling_Locking, then
-   --  set the ceiling to Prio.
+   function Init_Mutex (L : RTS_Lock_Ptr; Prio : Any_Priority) return C.int;
+   --  Initialize the mutex L. If Ceiling_Support is True, then set the ceiling
+   --  to Prio. Returns 0 for success, or ENOMEM for out-of-memory.
 
    -------------------
    -- Abort_Handler --
@@ -190,7 +216,7 @@ package body System.Task_Primitives.Operations is
       pragma Unreferenced (signo);
 
       Self_Id : constant Task_Id := Self;
-      Result  : Interfaces.C.int;
+      Result  : C.int;
       Old_Set : aliased sigset_t;
 
    begin
@@ -272,30 +298,26 @@ package body System.Task_Primitives.Operations is
    -- Init_Mutex --
    ----------------
 
-   function Init_Mutex
-     (L : RTS_Lock_Ptr; Prio : Any_Priority)
-     return Interfaces.C.int
-   is
+   function Init_Mutex (L : RTS_Lock_Ptr; Prio : Any_Priority) return C.int is
       Mutex_Attr : aliased pthread_mutexattr_t;
-      Result : Interfaces.C.int;
+      Result, Result_2 : C.int;
+
    begin
       Result := pthread_mutexattr_init (Mutex_Attr'Access);
-      pragma Assert (Result = 0 or else Result = ENOMEM);
+      pragma Assert (Result in 0 | ENOMEM);
 
       if Result = ENOMEM then
-         return ENOMEM;
+         return Result;
       end if;
 
-      if Locking_Policy = 'C' then
-         if Superuser then
-            Result := pthread_mutexattr_setprotocol
-              (Mutex_Attr'Access, PTHREAD_PRIO_PROTECT);
-            pragma Assert (Result = 0);
+      if Ceiling_Support then
+         Result := pthread_mutexattr_setprotocol
+           (Mutex_Attr'Access, PTHREAD_PRIO_PROTECT);
+         pragma Assert (Result = 0);
 
-            Result := pthread_mutexattr_setprioceiling
-              (Mutex_Attr'Access, Interfaces.C.int (Prio));
-            pragma Assert (Result = 0);
-         end if;
+         Result := pthread_mutexattr_setprioceiling
+           (Mutex_Attr'Access, Prio_To_Linux_Prio (Prio));
+         pragma Assert (Result = 0);
 
       elsif Locking_Policy = 'I' then
          Result := pthread_mutexattr_setprotocol
@@ -304,16 +326,11 @@ package body System.Task_Primitives.Operations is
       end if;
 
       Result := pthread_mutex_init (L, Mutex_Attr'Access);
-      pragma Assert (Result = 0 or else Result = ENOMEM);
+      pragma Assert (Result in 0 | ENOMEM);
 
-      if Result = ENOMEM then
-         Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
-         return ENOMEM;
-      end if;
-
-      Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
-      pragma Assert (Result = 0);
-      return 0;
+      Result_2 := pthread_mutexattr_destroy (Mutex_Attr'Access);
+      pragma Assert (Result_2 = 0);
+      return Result; -- of pthread_mutex_init, not pthread_mutexattr_destroy
    end Init_Mutex;
 
    ---------------------
@@ -327,14 +344,14 @@ package body System.Task_Primitives.Operations is
    --  routines should be able to be handled safely.
 
    procedure Initialize_Lock
-     (Prio : System.Any_Priority;
+     (Prio : Any_Priority;
       L    : not null access Lock)
    is
    begin
       if Locking_Policy = 'R' then
          declare
             RWlock_Attr : aliased pthread_rwlockattr_t;
-            Result      : Interfaces.C.int;
+            Result      : C.int;
 
          begin
             --  Set the rwlock to prefer writer to avoid writers starvation
@@ -349,7 +366,7 @@ package body System.Task_Primitives.Operations is
 
             Result := pthread_rwlock_init (L.RW'Access, RWlock_Attr'Access);
 
-            pragma Assert (Result = 0 or else Result = ENOMEM);
+            pragma Assert (Result in 0 | ENOMEM);
 
             if Result = ENOMEM then
                raise Storage_Error with "Failed to allocate a lock";
@@ -378,7 +395,7 @@ package body System.Task_Primitives.Operations is
    -------------------
 
    procedure Finalize_Lock (L : not null access Lock) is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if Locking_Policy = 'R' then
          Result := pthread_rwlock_destroy (L.RW'Access);
@@ -389,7 +406,7 @@ package body System.Task_Primitives.Operations is
    end Finalize_Lock;
 
    procedure Finalize_Lock (L : not null access RTS_Lock) is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       Result := pthread_mutex_destroy (L);
       pragma Assert (Result = 0);
@@ -403,7 +420,7 @@ package body System.Task_Primitives.Operations is
      (L                 : not null access Lock;
       Ceiling_Violation : out Boolean)
    is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if Locking_Policy = 'R' then
          Result := pthread_rwlock_wrlock (L.RW'Access);
@@ -413,15 +430,15 @@ package body System.Task_Primitives.Operations is
 
       --  The cause of EINVAL is a priority ceiling violation
 
+      pragma Assert (Result in 0 | EINVAL);
       Ceiling_Violation := Result = EINVAL;
-      pragma Assert (Result = 0 or else Ceiling_Violation);
    end Write_Lock;
 
    procedure Write_Lock
      (L           : not null access RTS_Lock;
       Global_Lock : Boolean := False)
    is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if not Single_Lock or else Global_Lock then
          Result := pthread_mutex_lock (L);
@@ -430,7 +447,7 @@ package body System.Task_Primitives.Operations is
    end Write_Lock;
 
    procedure Write_Lock (T : Task_Id) is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if not Single_Lock then
          Result := pthread_mutex_lock (T.Common.LL.L'Access);
@@ -446,7 +463,7 @@ package body System.Task_Primitives.Operations is
      (L                 : not null access Lock;
       Ceiling_Violation : out Boolean)
    is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if Locking_Policy = 'R' then
          Result := pthread_rwlock_rdlock (L.RW'Access);
@@ -456,8 +473,8 @@ package body System.Task_Primitives.Operations is
 
       --  The cause of EINVAL is a priority ceiling violation
 
+      pragma Assert (Result in 0 | EINVAL);
       Ceiling_Violation := Result = EINVAL;
-      pragma Assert (Result = 0 or else Ceiling_Violation);
    end Read_Lock;
 
    ------------
@@ -465,7 +482,7 @@ package body System.Task_Primitives.Operations is
    ------------
 
    procedure Unlock (L : not null access Lock) is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if Locking_Policy = 'R' then
          Result := pthread_rwlock_unlock (L.RW'Access);
@@ -479,7 +496,7 @@ package body System.Task_Primitives.Operations is
      (L           : not null access RTS_Lock;
       Global_Lock : Boolean := False)
    is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if not Single_Lock or else Global_Lock then
          Result := pthread_mutex_unlock (L);
@@ -488,7 +505,7 @@ package body System.Task_Primitives.Operations is
    end Unlock;
 
    procedure Unlock (T : Task_Id) is
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       if not Single_Lock then
          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
@@ -504,7 +521,7 @@ package body System.Task_Primitives.Operations is
 
    procedure Set_Ceiling
      (L    : not null access Lock;
-      Prio : System.Any_Priority)
+      Prio : Any_Priority)
    is
       pragma Unreferenced (L, Prio);
    begin
@@ -521,7 +538,7 @@ package body System.Task_Primitives.Operations is
    is
       pragma Unreferenced (Reason);
 
-      Result : Interfaces.C.int;
+      Result : C.int;
 
    begin
       pragma Assert (Self_ID = Self);
@@ -535,7 +552,7 @@ package body System.Task_Primitives.Operations is
 
       --  EINTR is not considered a failure
 
-      pragma Assert (Result = 0 or else Result = EINTR);
+      pragma Assert (Result in 0 | EINTR);
    end Sleep;
 
    -----------------
@@ -560,7 +577,7 @@ package body System.Task_Primitives.Operations is
       Check_Time : Duration := Base_Time;
       Abs_Time   : Duration;
       Request    : aliased timespec;
-      Result     : Interfaces.C.int;
+      Result     : C.int;
 
    begin
       Timedout := True;
@@ -588,7 +605,7 @@ package body System.Task_Primitives.Operations is
             Check_Time := Monotonic_Clock;
             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 
-            if Result = 0 or else Result = EINTR then
+            if Result in 0 | EINTR then
 
                --  Somebody may have called Wakeup for us
 
@@ -618,7 +635,7 @@ package body System.Task_Primitives.Operations is
       Abs_Time   : Duration;
       Request    : aliased timespec;
 
-      Result : Interfaces.C.int;
+      Result : C.int;
       pragma Warnings (Off, Result);
 
    begin
@@ -651,9 +668,7 @@ package body System.Task_Primitives.Operations is
             Check_Time := Monotonic_Clock;
             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 
-            pragma Assert (Result = 0 or else
-              Result = ETIMEDOUT or else
-              Result = EINTR);
+            pragma Assert (Result in 0 | ETIMEDOUT | EINTR);
          end loop;
 
          Self_ID.Common.State := Runnable;
@@ -674,7 +689,7 @@ package body System.Task_Primitives.Operations is
 
    function Monotonic_Clock return Duration is
       TS     : aliased timespec;
-      Result : int;
+      Result : C.int;
    begin
       Result := clock_gettime
         (clock_id => OSC.CLOCK_RT_Ada, tp => TS'Unchecked_Access);
@@ -689,7 +704,7 @@ package body System.Task_Primitives.Operations is
 
    function RT_Resolution return Duration is
       TS     : aliased timespec;
-      Result : int;
+      Result : C.int;
 
    begin
       Result := clock_getres (OSC.CLOCK_REALTIME, TS'Unchecked_Access);
@@ -704,7 +719,7 @@ package body System.Task_Primitives.Operations is
 
    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
       pragma Unreferenced (Reason);
-      Result : Interfaces.C.int;
+      Result : C.int;
    begin
       Result := pthread_cond_signal (T.Common.LL.CV'Access);
       pragma Assert (Result = 0);
@@ -715,7 +730,7 @@ package body System.Task_Primitives.Operations is
    -----------
 
    procedure Yield (Do_Yield : Boolean := True) is
-      Result : Interfaces.C.int;
+      Result : C.int;
       pragma Unreferenced (Result);
    begin
       if Do_Yield then
@@ -729,15 +744,15 @@ package body System.Task_Primitives.Operations is
 
    procedure Set_Priority
      (T                   : Task_Id;
-      Prio                : System.Any_Priority;
+      Prio                : Any_Priority;
       Loss_Of_Inheritance : Boolean := False)
    is
       pragma Unreferenced (Loss_Of_Inheritance);
 
-      Result : Interfaces.C.int;
+      Result : C.int;
       Param  : aliased struct_sched_param;
 
-      function Get_Policy (Prio : System.Any_Priority) return Character;
+      function Get_Policy (Prio : Any_Priority) return Character;
       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
       --  Get priority specific dispatching policy
 
@@ -748,9 +763,7 @@ package body System.Task_Primitives.Operations is
    begin
       T.Common.Current_Priority := Prio;
 
-      --  Priorities are 1 .. 99 on GNU/Linux, so we map 0 .. 98 to 1 .. 99
-
-      Param.sched_priority := Interfaces.C.int (Prio) + 1;
+      Param.sched_priority := Prio_To_Linux_Prio (Prio);
 
       if Dispatching_Policy = 'R'
         or else Priority_Specific_Policy = 'R'
@@ -776,14 +789,14 @@ package body System.Task_Primitives.Operations is
               SCHED_OTHER, Param'Access);
       end if;
 
-      pragma Assert (Result = 0 or else Result = EPERM);
+      pragma Assert (Result in 0 | EPERM | EINVAL);
    end Set_Priority;
 
    ------------------
    -- Get_Priority --
    ------------------
 
-   function Get_Priority (T : Task_Id) return System.Any_Priority is
+   function Get_Priority (T : Task_Id) return Any_Priority is
    begin
       return T.Common.Current_Priority;
    end Get_Priority;
@@ -817,7 +830,7 @@ package body System.Task_Primitives.Operations is
             Len    : Natural := 0;
             --  Length of the task name contained in Task_Name
 
-            Result : int;
+            Result : C.int;
             --  Result from the prctl call
          begin
             Result := prctl (PR_GET_NAME, unsigned_long (Thread_Name'Address));
@@ -849,7 +862,7 @@ package body System.Task_Primitives.Operations is
       elsif Self_ID.Common.Task_Image_Len > 0 then
          declare
             Task_Name : String (1 .. Parameters.Max_Task_Image_Length + 1);
-            Result    : int;
+            Result    : C.int;
 
          begin
             Task_Name (1 .. Self_ID.Common.Task_Image_Len) :=
@@ -868,7 +881,7 @@ package body System.Task_Primitives.Operations is
       then
          declare
             Stack  : aliased stack_t;
-            Result : Interfaces.C.int;
+            Result : C.int;
          begin
             Stack.ss_sp    := Self_ID.Common.Task_Alternate_Stack;
             Stack.ss_size  := Alternate_Stack_Size;
@@ -903,7 +916,7 @@ package body System.Task_Primitives.Operations is
    --------------------
 
    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
-      Result    : Interfaces.C.int;
+      Result    : C.int;
       Cond_Attr : aliased pthread_condattr_t;
 
    begin
@@ -917,7 +930,7 @@ package body System.Task_Primitives.Operations is
 
       if not Single_Lock then
          if Init_Mutex
-           (Self_ID.Common.LL.L'Access, System.Any_Priority'Last) /= 0
+           (Self_ID.Common.LL.L'Access, Any_Priority'Last) /= 0
          then
             Succeeded := False;
             return;
@@ -925,7 +938,7 @@ package body System.Task_Primitives.Operations is
       end if;
 
       Result := pthread_condattr_init (Cond_Attr'Access);
-      pragma Assert (Result = 0 or else Result = ENOMEM);
+      pragma Assert (Result in 0 | ENOMEM);
 
       if Result = 0 then
          Result := GNAT_pthread_condattr_setup (Cond_Attr'Access);
@@ -934,7 +947,7 @@ package body System.Task_Primitives.Operations is
          Result :=
            pthread_cond_init
              (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
-         pragma Assert (Result = 0 or else Result = ENOMEM);
+         pragma Assert (Result in 0 | ENOMEM);
       end if;
 
       if Result = 0 then
@@ -960,14 +973,14 @@ package body System.Task_Primitives.Operations is
      (T          : Task_Id;
       Wrapper    : System.Address;
       Stack_Size : System.Parameters.Size_Type;
-      Priority   : System.Any_Priority;
+      Priority   : Any_Priority;
       Succeeded  : out Boolean)
    is
       Thread_Attr         : aliased pthread_attr_t;
-      Adjusted_Stack_Size : Interfaces.C.size_t;
-      Result              : Interfaces.C.int;
+      Adjusted_Stack_Size : C.size_t;
+      Result              : C.int;
 
-      use type System.Multiprocessors.CPU_Range;
+      use type Multiprocessors.CPU_Range, Interfaces.C.size_t;
 
    begin
       --  Check whether both Dispatching_Domain and CPU are specified for
@@ -975,7 +988,7 @@ package body System.Task_Primitives.Operations is
       --  processors for the domain.
 
       if T.Common.Domain /= null
-        and then T.Common.Base_CPU /= System.Multiprocessors.Not_A_Specific_CPU
+        and then T.Common.Base_CPU /= Multiprocessors.Not_A_Specific_CPU
         and then
           (T.Common.Base_CPU not in T.Common.Domain'Range
             or else not T.Common.Domain (T.Common.Base_CPU))
@@ -984,11 +997,10 @@ package body System.Task_Primitives.Operations is
          return;
       end if;
 
-      Adjusted_Stack_Size :=
-         Interfaces.C.size_t (Stack_Size + Alternate_Stack_Size);
+      Adjusted_Stack_Size := C.size_t (Stack_Size + Alternate_Stack_Size);
 
       Result := pthread_attr_init (Thread_Attr'Access);
-      pragma Assert (Result = 0 or else Result = ENOMEM);
+      pragma Assert (Result in 0 | ENOMEM);
 
       if Result /= 0 then
          Succeeded := False;
@@ -1013,16 +1025,15 @@ package body System.Task_Primitives.Operations is
 
       --  Do nothing if required support not provided by the operating system
 
-      if pthread_attr_setaffinity_np'Address = System.Null_Address then
+      if pthread_attr_setaffinity_np'Address = Null_Address then
          null;
 
       --  Support is available
 
-      elsif T.Common.Base_CPU /= System.Multiprocessors.Not_A_Specific_CPU then
+      elsif T.Common.Base_CPU /= Multiprocessors.Not_A_Specific_CPU then
          declare
             CPUs    : constant size_t :=
-                        Interfaces.C.size_t
-                          (System.Multiprocessors.Number_Of_CPUs);
+                        C.size_t (Multiprocessors.Number_Of_CPUs);
             CPU_Set : constant cpu_set_t_ptr := CPU_ALLOC (CPUs);
             Size    : constant size_t := CPU_ALLOC_SIZE (CPUs);
 
@@ -1061,8 +1072,7 @@ package body System.Task_Primitives.Operations is
       then
          declare
             CPUs    : constant size_t :=
-                        Interfaces.C.size_t
-                          (System.Multiprocessors.Number_Of_CPUs);
+                        C.size_t (Multiprocessors.Number_Of_CPUs);
             CPU_Set : constant cpu_set_t_ptr := CPU_ALLOC (CPUs);
             Size    : constant size_t := CPU_ALLOC_SIZE (CPUs);
 
@@ -1103,8 +1113,7 @@ package body System.Task_Primitives.Operations is
          Thread_Body_Access (Wrapper),
          To_Address (T));
 
-      pragma Assert
-        (Result = 0 or else Result = EAGAIN or else Result = ENOMEM);
+      pragma Assert (Result in 0 | EAGAIN | ENOMEM);
 
       if Result /= 0 then
          Succeeded := False;
@@ -1126,7 +1135,7 @@ package body System.Task_Primitives.Operations is
    ------------------
 
    procedure Finalize_TCB (T : Task_Id) is
-      Result : Interfaces.C.int;
+      Result : C.int;
 
    begin
       if not Single_Lock then
@@ -1158,7 +1167,7 @@ package body System.Task_Primitives.Operations is
    ----------------
 
    procedure Abort_Task (T : Task_Id) is
-      Result : Interfaces.C.int;
+      Result : C.int;
 
       ESRCH : constant := 3; -- No such process
       --  It can happen that T has already vanished, in which case pthread_kill
@@ -1170,7 +1179,7 @@ package body System.Task_Primitives.Operations is
            pthread_kill
              (T.Common.LL.Thread,
               Signal (System.Interrupt_Management.Abort_Task_Interrupt));
-         pragma Assert (Result = 0 or else Result = ESRCH);
+         pragma Assert (Result in 0 | ESRCH);
       end if;
    end Abort_Task;
 
@@ -1179,7 +1188,7 @@ package body System.Task_Primitives.Operations is
    ----------------
 
    procedure Initialize (S : in out Suspension_Object) is
-      Result : Interfaces.C.int;
+      Result : C.int;
 
    begin
       --  Initialize internal state (always to False (RM D.10(6)))
@@ -1191,7 +1200,7 @@ package body System.Task_Primitives.Operations is
 
       Result := pthread_mutex_init (S.L'Access, null);
 
-      pragma Assert (Result = 0 or else Result = ENOMEM);
+      pragma Assert (Result in 0 | ENOMEM);
 
       if Result = ENOMEM then
          raise Storage_Error;
@@ -1201,7 +1210,7 @@ package body System.Task_Primitives.Operations is
 
       Result := pthread_cond_init (S.CV'Access, null);
 
-      pragma Assert (Result = 0 or else Result = ENOMEM);
+      pragma Assert (Result in 0 | ENOMEM);
 
       if Result /= 0 then
          Result := pthread_mutex_destroy (S.L'Access);
@@ -1218,7 +1227,7 @@ package body System.Task_Primitives.Operations is
    --------------
 
    procedure Finalize (S : in out Suspension_Object) is
-      Result : Interfaces.C.int;
+      Result : C.int;
 
    begin
       --  Destroy internal mutex
@@ -1249,7 +1258,7 @@ package body System.Task_Primitives.Operations is
    ---------------
 
    procedure Set_False (S : in out Suspension_Object) is
-      Result : Interfaces.C.int;
+      Result : C.int;
 
    begin
       SSL.Abort_Defer.all;
@@ -1270,7 +1279,7 @@ package body System.Task_Primitives.Operations is
    --------------
 
    procedure Set_True (S : in out Suspension_Object) is
-      Result : Interfaces.C.int;
+      Result : C.int;
 
    begin
       SSL.Abort_Defer.all;
@@ -1305,7 +1314,7 @@ package body System.Task_Primitives.Operations is
    ------------------------
 
    procedure Suspend_Until_True (S : in out Suspension_Object) is
-      Result : Interfaces.C.int;
+      Result : C.int;
 
    begin
       SSL.Abort_Defer.all;
@@ -1343,7 +1352,7 @@ package body System.Task_Primitives.Operations is
                --  POSIX does not guarantee it so this may change in future.
 
                Result := pthread_cond_wait (S.CV'Access, S.L'Access);
-               pragma Assert (Result = 0 or else Result = EINTR);
+               pragma Assert (Result in 0 | EINTR);
 
                exit when not S.Waiting;
             end loop;
@@ -1456,7 +1465,7 @@ package body System.Task_Primitives.Operations is
       act     : aliased struct_sigaction;
       old_act : aliased struct_sigaction;
       Tmp_Set : aliased sigset_t;
-      Result  : Interfaces.C.int;
+      Result  : C.int;
       --  Whether to use an alternate signal stack for stack overflows
 
       function State
@@ -1538,7 +1547,7 @@ package body System.Task_Primitives.Operations is
    -----------------------
 
    procedure Set_Task_Affinity (T : ST.Task_Id) is
-      use type System.Multiprocessors.CPU_Range;
+      use type Multiprocessors.CPU_Range;
 
    begin
       --  Do nothing if there is no support for setting affinities or the
@@ -1546,17 +1555,16 @@ package body System.Task_Primitives.Operations is
       --  yet been created then the proper affinity will be set during its
       --  creation.
 
-      if pthread_setaffinity_np'Address /= System.Null_Address
+      if pthread_setaffinity_np'Address /= Null_Address
         and then T.Common.LL.Thread /= Null_Thread_Id
       then
          declare
             CPUs    : constant size_t :=
-                        Interfaces.C.size_t
-                          (System.Multiprocessors.Number_Of_CPUs);
+                        C.size_t (Multiprocessors.Number_Of_CPUs);
             CPU_Set : cpu_set_t_ptr := null;
             Size    : constant size_t := CPU_ALLOC_SIZE (CPUs);
 
-            Result  : Interfaces.C.int;
+            Result  : C.int;
 
          begin
             --  We look at the specific CPU (Base_CPU) first, then at the
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index 8f3cf1e..e92a954 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -3133,7 +3133,11 @@ package body Sem_Ch3 is
 
             when N_Derived_Type_Definition =>
                Derived_Type_Declaration (T, N, T /= Def_Id);
-               if Ekind (T) /= E_Void and then Has_Predicates (T) then -- ????
+
+               --  Inherit predicates from parent, and protect against
+               --  illegal derivations.
+
+               if Is_Type (T) and then Has_Predicates (T) then
                   Set_Has_Predicates (Def_Id);
                end if;