Index: widechar.adb
===================================================================
--- widechar.adb	(revision 118179)
+++ widechar.adb	(working copy)
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2005, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2006, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -52,20 +52,35 @@ package body Widechar is
    is
    begin
       case Wide_Character_Encoding_Method is
+
+         --  For Hex mode, just test for an ESC character. The ESC character
+         --  cannot appear in any other context in a legal Ada program.
+
          when WCEM_Hex =>
             return S (P) = ASCII.ESC;
 
-         when WCEM_Upper     |
-              WCEM_Shift_JIS |
-              WCEM_EUC       |
-              WCEM_UTF8      =>
-            return S (P) >= Character'Val (16#80#);
+         --  For brackets, just test ["x where x is a hex character. This is
+         --  sufficient test, since this sequence cannot otherwise appear in a
+         --  legal Ada program.
 
          when WCEM_Brackets =>
             return P <= S'Last - 2
               and then S (P) = '['
               and then S (P + 1) = '"'
-              and then S (P + 2) /= '"';
+              and then (S (P + 2) in '0' .. '9'
+                            or else
+                           S (P + 2) in 'a' .. 'f'
+                            or else
+                        S (P + 2) in 'A' .. 'F');
+
+         --  All other encoding methods use the upper bit set in the first
+         --  character to uniquely represent a wide character.
+
+         when WCEM_Upper     |
+              WCEM_Shift_JIS |
+              WCEM_EUC       |
+              WCEM_UTF8      =>
+            return S (P) >= Character'Val (16#80#);
       end case;
    end Is_Start_Of_Wide_Char;
 
@@ -89,6 +104,7 @@ package body Widechar is
       Err : out Boolean)
    is
       P_Init : constant Source_Ptr := P;
+      Chr    : Character;
 
       function In_Char return Character;
       --  Function to obtain characters of wide character escape sequence
@@ -108,7 +124,18 @@ package body Widechar is
    --  Start of processingf for Scan_Wide
 
    begin
-      C := Char_Code (WC_In (In_Char, Wide_Character_Encoding_Method));
+      Chr := In_Char;
+
+      --  Scan out the wide character. if the first character is a bracket,
+      --  we allow brackets encoding regardless of the standard encoding
+      --  method being used, but otherwise we use this standard method.
+
+      if Chr = '[' then
+         C := Char_Code (WC_In (Chr, WCEM_Brackets));
+      else
+         C := Char_Code (WC_In (Chr, Wide_Character_Encoding_Method));
+      end if;
+
       Err := False;
       Wide_Char_Byte_Count := Wide_Char_Byte_Count + Nat (P - P_Init - 1);