2008-04-08 Robert Dewar <dewar@adacore.com>

	* a-except-2005.ads, a-except-2005.adb, a-except.ads, a-except.adb
	(Raise_Exception): In accordance with AI-446, raise CE for Null_Id
	(Raise_Exception_Always): Fix documentation accordingly

From-SVN: r134018

gcc/ada/a-except-2005.adb

@@ -420,11 +420,11 @@ package body Ada.Exceptions is
    -- Run-Time Check Routines --
    -----------------------------
 
-   --  These routines are called from the runtime to raise a specific
-   --  exception with a reason message attached. The parameters are
-   --  the file name and line number in each case. The names are keyed
-   --  to the codes defined in Types.ads and a-types.h (for example,
-   --  the name Rcheck_05 refers to the Reason whose Pos code is 5).
+   --  These routines raise a specific exception with a reason message
+   --  attached. The parameters are the file name and line number in each
+   --  case. The names are keyed to the codes defined in types.ads and
+   --  a-types.h (for example, the name Rcheck_05 refers to the Reason
+   --  RT_Exception_Code'Val (5)).
 
    procedure Rcheck_00 (File : System.Address; Line : Integer);
    procedure Rcheck_01 (File : System.Address; Line : Integer);
@@ -838,20 +838,20 @@ package body Ada.Exceptions is
      (E       : Exception_Id;
       Message : String := "")
    is
+      EF : Exception_Id := E;
+
    begin
-      if E /= null then
-         Exception_Data.Set_Exception_Msg (E, Message);
-         Abort_Defer.all;
-         Raise_Current_Excep (E);
+      --  Raise CE if E = Null_ID (AI-446)
+
+      if E = null then
+         EF := Constraint_Error'Identity;
       end if;
 
-      --  Note: if E is null, then we simply return, which is correct Ada 95
-      --  semantics. If we are operating in Ada 2005 mode, then the expander
-      --  generates a raise Constraint_Error immediately following the call
-      --  to provide the required Ada 2005 semantics (see AI-329). We do it
-      --  this way to avoid having run time dependencies on the Ada version.
+      --  Go ahead and raise appropriate exception
 
-      return;
+      Exception_Data.Set_Exception_Msg (EF, Message);
+      Abort_Defer.all;
+      Raise_Current_Excep (EF);
    end Raise_Exception;
 
    ----------------------------

gcc/ada/a-except-2005.ads

@@ -93,12 +93,8 @@ package Ada.Exceptions is
    pragma Ada_05 (Wide_Wide_Exception_Name);
 
    procedure Raise_Exception (E : Exception_Id; Message : String := "");
-   --  Note: it would be really nice to give a pragma No_Return for this
-   --  procedure, but it would be wrong, since Raise_Exception does return
-   --  if given the null exception. However we do special case the name in
-   --  the test in the compiler for issuing a warning for a missing return
-   --  after this call. Program_Error seems reasonable enough in such a case.
-   --  See also the routine Raise_Exception_Always in the private part.
+   pragma No_Return (Raise_Exception);
+   --  Note: In accordance with AI-466, CE is raised if E = Null_Id
 
    function Exception_Message (X : Exception_Occurrence) return String;
 
@@ -135,11 +131,10 @@ package Ada.Exceptions is
      (Source : Exception_Occurrence)
       return   Exception_Occurrence_Access;
 
-   --  Ada 2005 (AI-438): The language revision introduces the
-   --  following subprograms and attribute definitions. We do not
-   --  provide them explicitly; instead, the corresponding stream
-   --  attributes are made available through a pragma Stream_Convert
-   --  in the private part of this package.
+   --  Ada 2005 (AI-438): The language revision introduces the following
+   --  subprograms and attribute definitions. We do not provide them
+   --  explicitly. instead, the corresponding stream attributes are made
+   --  available through a pragma Stream_Convert in the private part.
 
    --  procedure Read_Exception_Occurrence
    --    (Stream : not null access Ada.Streams.Root_Stream_Type'Class;
@@ -209,10 +204,10 @@ private
    pragma No_Return (Raise_Exception_Always);
    pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception");
    --  This differs from Raise_Exception only in that the caller has determined
-   --  that for sure the parameter E is not null, and that therefore the call
-   --  to this procedure cannot return. The expander converts Raise_Exception
-   --  calls to Raise_Exception_Always if it can determine this is the case.
-   --  The Export allows this routine to be accessed from Pure units.
+   --  that for sure the parameter E is not null, and that therefore no check
+   --  for Null_Id is required. The expander converts Raise_Exception calls to
+   --  Raise_Exception_Always if it can determine this is the case. The Export
+   --  allows this routine to be accessed from Pure units.
 
    procedure Raise_From_Signal_Handler
      (E : Exception_Id;

gcc/ada/a-except.adb

@@ -377,11 +377,11 @@ package body Ada.Exceptions is
    -- Run-Time Check Routines --
    -----------------------------
 
-   --  These routines are called from the runtime to raise a specific
-   --  exception with a reason message attached. The parameters are
-   --  the file name and line number in each case. The names are keyed
-   --  to the codes defined in Types.ads and a-types.h (for example,
-   --  the name Rcheck_05 refers to the Reason whose Pos code is 5).
+   --  These routines raise a specific exception with a reason message
+   --  attached. The parameters are the file name and line number in each
+   --  case. The names are keyed to the codes defined in types.ads and
+   --  a-types.h (for example, the name Rcheck_05 refers to the Reason
+   --  RT_Exception_Code'Val (5)).
 
    procedure Rcheck_00 (File : System.Address; Line : Integer);
    procedure Rcheck_01 (File : System.Address; Line : Integer);
@@ -807,16 +807,20 @@ package body Ada.Exceptions is
      (E       : Exception_Id;
       Message : String := "")
    is
+      EF : Exception_Id := E;
+
    begin
-      if E /= null then
-         Exception_Data.Set_Exception_Msg (E, Message);
-         Abort_Defer.all;
-         Raise_Current_Excep (E);
+      --  Raise CE if E = Null_ID (AI-446)
+
+      if E = null then
+         EF := Constraint_Error'Identity;
       end if;
 
-      --  Note: if E is null then just return (Ada 95 semantics)
+      --  Go ahead and raise appropriate exception
 
-      return;
+      Exception_Data.Set_Exception_Msg (EF, Message);
+      Abort_Defer.all;
+      Raise_Current_Excep (EF);
    end Raise_Exception;
 
    ----------------------------

gcc/ada/a-except.ads

@@ -84,12 +84,8 @@ package Ada.Exceptions is
    function Exception_Name (Id : Exception_Id) return String;
 
    procedure Raise_Exception (E : Exception_Id; Message : String := "");
-   --  Note: it would be really nice to give a pragma No_Return for this
-   --  procedure, but it would be wrong, since Raise_Exception does return if
-   --  given the null exception in Ada 95 mode. However we do special case the
-   --  name in the test in the compiler for issuing a warning for a missing
-   --  return after this call. Program_Error seems reasonable enough in such a
-   --  case. See also the routine Raise_Exception_Always in the private part.
+   pragma No_Return (Raise_Exception);
+   --  Note: In accordance with AI-466, CE is raised if E = Null_Id
 
    function Exception_Message (X : Exception_Occurrence) return String;
 
@@ -183,10 +179,10 @@ private
    pragma No_Return (Raise_Exception_Always);
    pragma Export (Ada, Raise_Exception_Always, "__gnat_raise_exception");
    --  This differs from Raise_Exception only in that the caller has determined
-   --  that for sure the parameter E is not null, and that therefore the call
-   --  to this procedure cannot return. The expander converts Raise_Exception
-   --  calls to Raise_Exception_Always if it can determine this is the case.
-   --  The Export allows this routine to be accessed from Pure units.
+   --  that for sure the parameter E is not null, and that therefore no check
+   --  for Null_Id is required. The expander converts Raise_Exception calls to
+   --  Raise_Exception_Always if it can determine this is the case. The Export
+   --  allows this routine to be accessed from Pure units.
 
    procedure Raise_From_Signal_Handler
      (E : Exception_Id;