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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             S E M _ C A S E                              --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1996-2009, 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- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --

-- http://www.gnu.org/licenses for a complete copy of the license.          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

with Atree;    use Atree;

with Einfo;    use Einfo;

with Errout;   use Errout;

with Namet;    use Namet;

with Nlists;   use Nlists;

with Nmake;    use Nmake;

with Opt;      use Opt;

with Sem;      use Sem;

with Sem_Aux;  use Sem_Aux;

with Sem_Case; use Sem_Case;

with Sem_Eval; use Sem_Eval;

with Sem_Res;  use Sem_Res;

with Sem_Util; use Sem_Util;

with Sem_Type; use Sem_Type;

with Snames;   use Snames;

with Stand;    use Stand;

with Sinfo;    use Sinfo;

with Tbuild;   use Tbuild;

with Uintp;    use Uintp;

with GNAT.Heap_Sort_G;

package body Sem_Case is

   -----------------------

   -- Local Subprograms --

   -----------------------

   type Sort_Choice_Table_Type is array (Nat range <>) of Choice_Bounds;

   --  This new array type is used as the actual table type for sorting

   --  discrete choices. The reason for not using Choice_Table_Type, is that

   --  in Sort_Choice_Table_Type we reserve entry 0 for the sorting algorithm

   --  (this is not absolutely necessary but it makes the code more

   --  efficient).

   procedure Check_Choices

     (Choice_Table   : in out Sort_Choice_Table_Type;

      Bounds_Type    : Entity_Id;

      Subtyp         : Entity_Id;

      Others_Present : Boolean;

      Case_Node      : Node_Id);

   --  This is the procedure which verifies that a set of case alternatives

   --  or record variant choices has no duplicates, and covers the range

   --  specified by Bounds_Type. Choice_Table contains the discrete choices

   --  to check. These must start at position 1.

   --

   --  Furthermore Choice_Table (0) must exist. This element is used by

   --  the sorting algorithm as a temporary. Others_Present is a flag

   --  indicating whether or not an Others choice is present. Finally

   --  Msg_Sloc gives the source location of the construct containing the

   --  choices in the Choice_Table.

   --

   --  Bounds_Type is the type whose range must be covered by the alternatives

   --

   --  Subtyp is the subtype of the expression. If its bounds are non-static

   --  the alternatives must cover its base type.

   function Choice_Image (Value : Uint; Ctype : Entity_Id) return Name_Id;

   --  Given a Pos value of enumeration type Ctype, returns the name

   --  ID of an appropriate string to be used in error message output.

   procedure Expand_Others_Choice

     (Case_Table     : Choice_Table_Type;

      Others_Choice  : Node_Id;

      Choice_Type    : Entity_Id);

   --  The case table is the table generated by a call to Analyze_Choices

   --  (with just 1 .. Last_Choice entries present). Others_Choice is a

   --  pointer to the N_Others_Choice node (this routine is only called if

   --  an others choice is present), and Choice_Type is the discrete type

   --  of the bounds. The effect of this call is to analyze the cases and

   --  determine the set of values covered by others. This choice list is

   --  set in the Others_Discrete_Choices field of the N_Others_Choice node.

   -------------------

   -- Check_Choices --

   -------------------

   procedure Check_Choices

     (Choice_Table    : in out Sort_Choice_Table_Type;

      Bounds_Type    : Entity_Id;

      Subtyp         : Entity_Id;

      Others_Present : Boolean;

      Case_Node      : Node_Id)

   is

      procedure Explain_Non_Static_Bound;

      --  Called when we find a non-static bound, requiring the base type to

      --  be covered. Provides where possible a helpful explanation of why the

      --  bounds are non-static, since this is not always obvious.

      function Lt_Choice (C1, C2 : Natural) return Boolean;

      --  Comparison routine for comparing Choice_Table entries. Use the lower

      --  bound of each Choice as the key.

      procedure Move_Choice (From : Natural; To : Natural);

      --  Move routine for sorting the Choice_Table

      package Sorting is new GNAT.Heap_Sort_G (Move_Choice, Lt_Choice);

      procedure Issue_Msg (Value1 : Node_Id; Value2 : Node_Id);

      procedure Issue_Msg (Value1 : Node_Id; Value2 : Uint);

      procedure Issue_Msg (Value1 : Uint;    Value2 : Node_Id);

      procedure Issue_Msg (Value1 : Uint;    Value2 : Uint);

      --  Issue an error message indicating that there are missing choices,

      --  followed by the image of the missing choices themselves which lie

      --  between Value1 and Value2 inclusive.

      ---------------

      -- Issue_Msg --

      ---------------

      procedure Issue_Msg (Value1 : Node_Id; Value2 : Node_Id) is

      begin

         Issue_Msg (Expr_Value (Value1), Expr_Value (Value2));

      end Issue_Msg;

      procedure Issue_Msg (Value1 : Node_Id; Value2 : Uint) is

      begin

         Issue_Msg (Expr_Value (Value1), Value2);

      end Issue_Msg;

      procedure Issue_Msg (Value1 : Uint; Value2 : Node_Id) is

      begin

         Issue_Msg (Value1, Expr_Value (Value2));

      end Issue_Msg;

      procedure Issue_Msg (Value1 : Uint; Value2 : Uint) is

         Msg_Sloc : constant Source_Ptr := Sloc (Case_Node);

      begin

         --  In some situations, we call this with a null range, and

         --  obviously we don't want to complain in this case!

         if Value1 > Value2 then

            return;

         end if;

         --  Case of only one value that is missing

         if Value1 = Value2 then

            if Is_Integer_Type (Bounds_Type) then

               Error_Msg_Uint_1 := Value1;

               Error_Msg ("missing case value: ^!", Msg_Sloc);

            else

               Error_Msg_Name_1 := Choice_Image (Value1, Bounds_Type);

               Error_Msg ("missing case value: %!", Msg_Sloc);

            end if;

         --  More than one choice value, so print range of values

         else

            if Is_Integer_Type (Bounds_Type) then

               Error_Msg_Uint_1 := Value1;

               Error_Msg_Uint_2 := Value2;

               Error_Msg ("missing case values: ^ .. ^!", Msg_Sloc);

            else

               Error_Msg_Name_1 := Choice_Image (Value1, Bounds_Type);

               Error_Msg_Name_2 := Choice_Image (Value2, Bounds_Type);

               Error_Msg ("missing case values: % .. %!", Msg_Sloc);

            end if;

         end if;

      end Issue_Msg;

      ---------------

      -- Lt_Choice --

      ---------------

      function Lt_Choice (C1, C2 : Natural) return Boolean is

      begin

         return

           Expr_Value (Choice_Table (Nat (C1)).Lo)

             <

           Expr_Value (Choice_Table (Nat (C2)).Lo);

      end Lt_Choice;

      -----------------

      -- Move_Choice --

      -----------------

      procedure Move_Choice (From : Natural; To : Natural) is

      begin

         Choice_Table (Nat (To)) := Choice_Table (Nat (From));

      end Move_Choice;

      ------------------------------

      -- Explain_Non_Static_Bound --

      ------------------------------

      procedure Explain_Non_Static_Bound is

         Expr : Node_Id;

      begin

         if Nkind (Case_Node) = N_Variant_Part then

            Expr := Name (Case_Node);

         else

            Expr := Expression (Case_Node);

         end if;

         if Bounds_Type /= Subtyp then

            --  If the case is a variant part, the expression is given by

            --  the discriminant itself, and the bounds are the culprits.

            if Nkind (Case_Node) = N_Variant_Part then

               Error_Msg_NE

                 ("bounds of & are not static," &

                     " alternatives must cover base type", Expr, Expr);

            --  If this is a case statement, the expression may be

            --  non-static or else the subtype may be at fault.

            elsif Is_Entity_Name (Expr) then

               Error_Msg_NE

                 ("bounds of & are not static," &

                    " alternatives must cover base type", Expr, Expr);

            else

               Error_Msg_N

                 ("subtype of expression is not static,"

                  & " alternatives must cover base type!", Expr);

            end if;

         --  Otherwise the expression is not static, even if the bounds of the

         --  type are, or else there are missing alternatives. If both, the

         --  additional information may be redundant but harmless.

         elsif not Is_Entity_Name (Expr) then

            Error_Msg_N

              ("subtype of expression is not static, "

               & "alternatives must cover base type!", Expr);

         end if;

      end Explain_Non_Static_Bound;

      --  Variables local to Check_Choices

      Choice    : Node_Id;

      Bounds_Lo : constant Node_Id := Type_Low_Bound  (Bounds_Type);

      Bounds_Hi : constant Node_Id := Type_High_Bound (Bounds_Type);

      Prev_Choice : Node_Id;

      Hi      : Uint;

      Lo      : Uint;

      Prev_Hi : Uint;

   --  Start of processing for Check_Choices

   begin

      --  Choice_Table must start at 0 which is an unused location used

      --  by the sorting algorithm. However the first valid position for

      --  a discrete choice is 1.

      pragma Assert (Choice_Table'First = 0);

      if Choice_Table'Last = 0 then

         if not Others_Present then

            Issue_Msg (Bounds_Lo, Bounds_Hi);

         end if;

         return;

      end if;

      Sorting.Sort (Positive (Choice_Table'Last));

      Lo      := Expr_Value (Choice_Table (1).Lo);

      Hi      := Expr_Value (Choice_Table (1).Hi);

      Prev_Hi := Hi;

      if not Others_Present and then Expr_Value (Bounds_Lo) < Lo then

         Issue_Msg (Bounds_Lo, Lo - 1);

         --  If values are missing outside of the subtype, add explanation.

         --  No additional message if only one value is missing.

         if Expr_Value (Bounds_Lo) < Lo - 1 then

            Explain_Non_Static_Bound;

         end if;

      end if;

      for J in 2 .. Choice_Table'Last loop

         Lo := Expr_Value (Choice_Table (J).Lo);

         Hi := Expr_Value (Choice_Table (J).Hi);

         if Lo <= Prev_Hi then

            Prev_Choice := Choice_Table (J - 1).Node;

            Choice      := Choice_Table (J).Node;

            if Sloc (Prev_Choice) <= Sloc (Choice) then

               Error_Msg_Sloc := Sloc (Prev_Choice);

               Error_Msg_N ("duplication of choice value#", Choice);

            else

               Error_Msg_Sloc := Sloc (Choice);

               Error_Msg_N ("duplication of choice value#", Prev_Choice);

            end if;

         elsif not Others_Present and then Lo /= Prev_Hi + 1 then

            Issue_Msg (Prev_Hi + 1, Lo - 1);

         end if;

         Prev_Hi := Hi;

      end loop;

      if not Others_Present and then Expr_Value (Bounds_Hi) > Hi then

         Issue_Msg (Hi + 1, Bounds_Hi);

         if Expr_Value (Bounds_Hi) > Hi + 1 then

            Explain_Non_Static_Bound;

         end if;

      end if;

   end Check_Choices;

   ------------------

   -- Choice_Image --

   ------------------

   function Choice_Image (Value : Uint; Ctype : Entity_Id) return Name_Id is

      Rtp : constant Entity_Id := Root_Type (Ctype);

      Lit : Entity_Id;

      C   : Int;

   begin

      --  For character, or wide [wide] character. If 7-bit ASCII graphic

      --  range, then build and return appropriate character literal name

      if Is_Standard_Character_Type (Ctype) then

         C := UI_To_Int (Value);

         if C in 16#20# .. 16#7E# then

            Set_Character_Literal_Name (Char_Code (UI_To_Int (Value)));

            return Name_Find;

         end if;

      --  For user defined enumeration type, find enum/char literal

      else

         Lit := First_Literal (Rtp);

         for J in 1 .. UI_To_Int (Value) loop

            Next_Literal (Lit);

         end loop;

         --  If enumeration literal, just return its value

         if Nkind (Lit) = N_Defining_Identifier then

            return Chars (Lit);

         --  For character literal, get the name and use it if it is

         --  for a 7-bit ASCII graphic character in 16#20#..16#7E#.

         else

            Get_Decoded_Name_String (Chars (Lit));

            if Name_Len = 3

              and then Name_Buffer (2) in

                Character'Val (16#20#) .. Character'Val (16#7E#)

            then

               return Chars (Lit);

            end if;

         end if;

      end if;

      --  If we fall through, we have a character literal which is not in

      --  the 7-bit ASCII graphic set. For such cases, we construct the

      --  name "type'val(nnn)" where type is the choice type, and nnn is

      --  the pos value passed as an argument to Choice_Image.

      Get_Name_String (Chars (First_Subtype (Ctype)));

      Add_Str_To_Name_Buffer ("'val(");

      UI_Image (Value);

      Add_Str_To_Name_Buffer (UI_Image_Buffer (1 .. UI_Image_Length));

      Add_Char_To_Name_Buffer (')');

      return Name_Find;

   end Choice_Image;

   --------------------------

   -- Expand_Others_Choice --

   --------------------------

   procedure Expand_Others_Choice

     (Case_Table    : Choice_Table_Type;

      Others_Choice : Node_Id;

      Choice_Type   : Entity_Id)

   is

      Loc         : constant Source_Ptr := Sloc (Others_Choice);

      Choice_List : constant List_Id    := New_List;

      Choice      : Node_Id;

      Exp_Lo      : Node_Id;

      Exp_Hi      : Node_Id;

      Hi          : Uint;

      Lo          : Uint;

      Previous_Hi : Uint;

      function Build_Choice (Value1, Value2 : Uint) return Node_Id;

      --  Builds a node representing the missing choices given by the

      --  Value1 and Value2. A N_Range node is built if there is more than

      --  one literal value missing. Otherwise a single N_Integer_Literal,

      --  N_Identifier or N_Character_Literal is built depending on what

      --  Choice_Type is.

      function Lit_Of (Value : Uint) return Node_Id;

      --  Returns the Node_Id for the enumeration literal corresponding to the

      --  position given by Value within the enumeration type Choice_Type.

      ------------------

      -- Build_Choice --

      ------------------

      function Build_Choice (Value1, Value2 : Uint) return Node_Id is

         Lit_Node : Node_Id;

         Lo, Hi   : Node_Id;

      begin

         --  If there is only one choice value missing between Value1 and

         --  Value2, build an integer or enumeration literal to represent it.

         if (Value2 - Value1) = 0 then

            if Is_Integer_Type (Choice_Type) then

               Lit_Node := Make_Integer_Literal (Loc, Value1);

               Set_Etype (Lit_Node, Choice_Type);

            else

               Lit_Node := Lit_Of (Value1);

            end if;

         --  Otherwise is more that one choice value that is missing between

         --  Value1 and Value2, therefore build a N_Range node of either

         --  integer or enumeration literals.

         else

            if Is_Integer_Type (Choice_Type) then

               Lo := Make_Integer_Literal (Loc, Value1);

               Set_Etype (Lo, Choice_Type);

               Hi := Make_Integer_Literal (Loc, Value2);

               Set_Etype (Hi, Choice_Type);

               Lit_Node :=

                 Make_Range (Loc,

                   Low_Bound  => Lo,

                   High_Bound => Hi);

            else

               Lit_Node :=

                 Make_Range (Loc,

                   Low_Bound  => Lit_Of (Value1),

                   High_Bound => Lit_Of (Value2));

            end if;

         end if;

         return Lit_Node;

      end Build_Choice;

      ------------

      -- Lit_Of --

      ------------

      function Lit_Of (Value : Uint) return Node_Id is

         Lit : Entity_Id;

      begin

         --  In the case where the literal is of type Character, there needs

         --  to be some special handling since there is no explicit chain

         --  of literals to search. Instead, a N_Character_Literal node

         --  is created with the appropriate Char_Code and Chars fields.

         if Is_Standard_Character_Type (Choice_Type) then

            Set_Character_Literal_Name (Char_Code (UI_To_Int (Value)));

            Lit := New_Node (N_Character_Literal, Loc);

            Set_Chars (Lit, Name_Find);

            Set_Char_Literal_Value (Lit, Value);

            Set_Etype (Lit, Choice_Type);

            Set_Is_Static_Expression (Lit, True);

            return Lit;

         --  Otherwise, iterate through the literals list of Choice_Type

         --  "Value" number of times until the desired literal is reached

         --  and then return an occurrence of it.

         else

            Lit := First_Literal (Choice_Type);

            for J in 1 .. UI_To_Int (Value) loop

               Next_Literal (Lit);

            end loop;

            return New_Occurrence_Of (Lit, Loc);

         end if;

      end Lit_Of;

   --  Start of processing for Expand_Others_Choice

   begin

      if Case_Table'Length = 0 then

         --  Special case: only an others case is present.

         --  The others case covers the full range of the type.

         if Is_Static_Subtype (Choice_Type) then

            Choice := New_Occurrence_Of (Choice_Type, Loc);

         else

            Choice := New_Occurrence_Of (Base_Type (Choice_Type), Loc);

         end if;

         Set_Others_Discrete_Choices (Others_Choice, New_List (Choice));

         return;

      end if;

      --  Establish the bound values for the choice depending upon whether

      --  the type of the case statement is static or not.

      if Is_OK_Static_Subtype (Choice_Type) then

         Exp_Lo := Type_Low_Bound (Choice_Type);

         Exp_Hi := Type_High_Bound (Choice_Type);

      else

         Exp_Lo := Type_Low_Bound (Base_Type (Choice_Type));

         Exp_Hi := Type_High_Bound (Base_Type (Choice_Type));

      end if;

      Lo := Expr_Value (Case_Table (Case_Table'First).Lo);

      Hi := Expr_Value (Case_Table (Case_Table'First).Hi);

      Previous_Hi := Expr_Value (Case_Table (Case_Table'First).Hi);

      --  Build the node for any missing choices that are smaller than any

      --  explicit choices given in the case.

      if Expr_Value (Exp_Lo) < Lo then

         Append (Build_Choice (Expr_Value (Exp_Lo), Lo - 1), Choice_List);

      end if;

      --  Build the nodes representing any missing choices that lie between

      --  the explicit ones given in the case.

      for J in Case_Table'First + 1 .. Case_Table'Last loop

         Lo := Expr_Value (Case_Table (J).Lo);

         Hi := Expr_Value (Case_Table (J).Hi);

         if Lo /= (Previous_Hi + 1) then

            Append_To (Choice_List, Build_Choice (Previous_Hi + 1, Lo - 1));

         end if;

         Previous_Hi := Hi;

      end loop;

      --  Build the node for any missing choices that are greater than any

      --  explicit choices given in the case.

      if Expr_Value (Exp_Hi) > Hi then

         Append (Build_Choice (Hi + 1, Expr_Value (Exp_Hi)), Choice_List);

      end if;

      Set_Others_Discrete_Choices (Others_Choice, Choice_List);

      --  Warn on null others list if warning option set

      if Warn_On_Redundant_Constructs

        and then Comes_From_Source (Others_Choice)

        and then Is_Empty_List (Choice_List)

      then

         Error_Msg_N ("?OTHERS choice is redundant", Others_Choice);

         Error_Msg_N ("\previous choices cover all values", Others_Choice);

      end if;

   end Expand_Others_Choice;

   -----------

   -- No_OP --

   -----------

   procedure No_OP (C : Node_Id) is

      pragma Warnings (Off, C);

   begin

      null;

   end No_OP;

   --------------------------------

   -- Generic_Choices_Processing --

   --------------------------------

   package body Generic_Choices_Processing is

      ---------------------

      -- Analyze_Choices --

      ---------------------

      procedure Analyze_Choices

        (N              : Node_Id;

         Subtyp         : Entity_Id;

         Choice_Table   : out Choice_Table_Type;

         Last_Choice    : out Nat;

         Raises_CE      : out Boolean;

         Others_Present : out Boolean)

      is

         pragma Assert (Choice_Table'First = 1);

         E : Entity_Id;

         Enode : Node_Id;

         --  This is where we post error messages for bounds out of range

         Nb_Choices        : constant Nat := Choice_Table'Length;

         Sort_Choice_Table : Sort_Choice_Table_Type (0 .. Nb_Choices);

         Choice_Type : constant Entity_Id := Base_Type (Subtyp);

         --  The actual type against which the discrete choices are resolved.

         --  Note that this type is always the base type not the subtype of the

         --  ruling expression, index or discriminant.

         Bounds_Type : Entity_Id;

         --  The type from which are derived the bounds of the values covered

         --  by the discrete choices (see 3.8.1 (4)). If a discrete choice

         --  specifies a value outside of these bounds we have an error.

         Bounds_Lo : Uint;

         Bounds_Hi : Uint;

         --  The actual bounds of the above type

         Expected_Type : Entity_Id;

         --  The expected type of each choice. Equal to Choice_Type, except if

         --  the expression is universal, in which case the choices can be of

         --  any integer type.

         Alt : Node_Id;

         --  A case statement alternative or a variant in a record type

         --  declaration.

         Choice : Node_Id;

         Kind   : Node_Kind;

         --  The node kind of the current Choice

         Others_Choice : Node_Id := Empty;

         --  Remember others choice if it is present (empty otherwise)

         procedure Check (Choice : Node_Id; Lo, Hi : Node_Id);

         --  Checks the validity of the bounds of a choice. When the bounds

         --  are static and no error occurred the bounds are entered into the

         --  choices table so that they can be sorted later on.

         -----------

         -- Check --

         -----------

         procedure Check (Choice : Node_Id; Lo, Hi : Node_Id) is

            Lo_Val : Uint;

            Hi_Val : Uint;

         begin

            --  First check if an error was already detected on either bounds

            if Etype (Lo) = Any_Type or else Etype (Hi) = Any_Type then

               return;

            --  Do not insert non static choices in the table to be sorted

            elsif not Is_Static_Expression (Lo)

              or else not Is_Static_Expression (Hi)

            then

               Process_Non_Static_Choice (Choice);

               return;

            --  Ignore range which raise constraint error

            elsif Raises_Constraint_Error (Lo)

              or else Raises_Constraint_Error (Hi)

            then

               Raises_CE := True;

               return;

            --  Otherwise we have an OK static choice

            else

               Lo_Val := Expr_Value (Lo);

               Hi_Val := Expr_Value (Hi);

               --  Do not insert null ranges in the choices table

               if Lo_Val > Hi_Val then

                  Process_Empty_Choice (Choice);

                  return;

               end if;

            end if;

            --  Check for low bound out of range

            if Lo_Val < Bounds_Lo then

               --  If the choice is an entity name, then it is a type, and we

               --  want to post the message on the reference to this entity.

               --  Otherwise we want to post it on the lower bound of the

               --  range.

               if Is_Entity_Name (Choice) then

                  Enode := Choice;

               else

                  Enode := Lo;

               end if;

               --  Specialize message for integer/enum type

               if Is_Integer_Type (Bounds_Type) then

                  Error_Msg_Uint_1 := Bounds_Lo;

                  Error_Msg_N ("minimum allowed choice value is^", Enode);

               else

                  Error_Msg_Name_1 := Choice_Image (Bounds_Lo, Bounds_Type);

                  Error_Msg_N ("minimum allowed choice value is%", Enode);

               end if;

            end if;

            --  Check for high bound out of range

            if Hi_Val > Bounds_Hi then

               --  If the choice is an entity name, then it is a type, and we

               --  want to post the message on the reference to this entity.

               --  Otherwise post it on the upper bound of the range.

               if Is_Entity_Name (Choice) then

                  Enode := Choice;

               else

                  Enode := Hi;

               end if;

               --  Specialize message for integer/enum type

               if Is_Integer_Type (Bounds_Type) then

                  Error_Msg_Uint_1 := Bounds_Hi;

                  Error_Msg_N ("maximum allowed choice value is^", Enode);

               else

                  Error_Msg_Name_1 := Choice_Image (Bounds_Hi, Bounds_Type);

                  Error_Msg_N ("maximum allowed choice value is%", Enode);

               end if;

            end if;

            --  Store bounds in the table

            --  Note: we still store the bounds, even if they are out of range,

            --  since this may prevent unnecessary cascaded errors for values

            --  that are covered by such an excessive range.

            Last_Choice := Last_Choice + 1;

            Sort_Choice_Table (Last_Choice).Lo   := Lo;

            Sort_Choice_Table (Last_Choice).Hi   := Hi;

            Sort_Choice_Table (Last_Choice).Node := Choice;

         end Check;

      --  Start of processing for Analyze_Choices

      begin

         Last_Choice    := 0;

         Raises_CE      := False;

         Others_Present := False;

         --  If Subtyp is not a static subtype Ada 95 requires then we use the

         --  bounds of its base type to determine the values covered by the

         --  discrete choices.

         if Is_OK_Static_Subtype (Subtyp) then

            Bounds_Type := Subtyp;

         else