{
    $Id$
    Copyright (C) 1993-98 by Florian Klaempfl

    This unit provides some help routines for type handling

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT 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
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 ****************************************************************************
}
unit types;

  interface

    uses
       objects,cobjects,globals,symtable,tree,aasm;

    type
       tmmxtype = (mmxno,mmxu8bit,mmxs8bit,mmxu16bit,mmxs16bit,
                   mmxu32bit,mmxs32bit,mmxfixed16,mmxsingle);

    { returns true, if def defines an ordinal type }
    function is_ordinal(def : pdef) : boolean;

    { true if p points to an open array def }
    function is_open_array(p : pdef) : boolean;

    { returns true, if def defines a signed data type (only for ordinal types) }
    function is_signed(def : pdef) : boolean;

    { returns true, if def uses FPU }
    function is_fpu(def : pdef) : boolean;

    { true if the return value is in EAX }
    function ret_in_acc(def : pdef) : boolean;

    { true if uses a parameter as return value }
    function ret_in_param(def : pdef) : boolean;

    { true if a const parameter is too large to copy }
    function dont_copy_const_param(def : pdef) : boolean;
    { true if we must never copy this parameter }
    const
       never_copy_const_param : boolean = false;

    { true, if def1 and def2 are semantical the same }
    function is_equal(def1,def2 : pdef) : boolean;

    { checks for type compatibility (subgroups of type)  }
    { used for case statements... probably missing stuff }
    { to use on other types                              }
    function is_subequal(def1, def2: pdef): boolean;

    { true, if two parameter lists are equal        }
    { if value_equal_const is true, call by value   }
    { and call by const parameter are assumed as    }
    { equal                                         }
    function equal_paras(def1,def2 : pdefcoll;value_equal_const : boolean) : boolean;

    { gibt den ordinalen Werten der Node zurueck oder falls sie }
    { keinen ordinalen Wert hat, wird ein Fehler erzeugt        }
    function get_ordinal_value(p : ptree) : longint;

    { if l isn't in the range of def a range check error is generated }
    procedure testrange(def : pdef;l : longint);

    { returns the range of def }
    procedure getrange(def : pdef;var l : longint;var h : longint);

    { generates a VMT for _class }
    procedure genvmt(_class : pobjectdef);

    { true, if p is a pointer to a const int value }
    function is_constintnode(p : ptree) : boolean;

    { like is_constintnode }
    function is_constboolnode(p : ptree) : boolean;
    function is_constrealnode(p : ptree) : boolean;
    function is_constcharnode(p : ptree) : boolean;

    { some type helper routines for MMX support }
    function is_mmx_able_array(p : pdef) : boolean;

    { returns the mmx type }
    function mmx_type(p : pdef) : tmmxtype;

  implementation

    uses verbose;

    function is_constintnode(p : ptree) : boolean;

      begin
         {DM: According to me, an orddef with anysize, is
          a correct constintnode. Anyway I commented changed s32bit check,
          because it caused problems with statements like a:=high(word).}
         is_constintnode:=((p^.treetype=ordconstn) and
           (p^.resulttype^.deftype=orddef) and
           (porddef(p^.resulttype)^.typ in [u8bit,s8bit,u16bit,s16bit,
            u32bit,s32bit,uauto]));
      end;

    function is_constcharnode(p : ptree) : boolean;

      begin
         is_constcharnode:=((p^.treetype=ordconstn) and
           (p^.resulttype^.deftype=orddef) and
           (porddef(p^.resulttype)^.typ=uchar));
      end;

    function is_constrealnode(p : ptree) : boolean;

      begin
         is_constrealnode:=(p^.treetype=realconstn);
      end;

    function is_constboolnode(p : ptree) : boolean;

      begin
         is_constboolnode:=((p^.treetype=ordconstn) and
           (p^.resulttype^.deftype=orddef) and
           (porddef(p^.resulttype)^.typ=bool8bit));
      end;

    function equal_paras(def1,def2 : pdefcoll;value_equal_const : boolean) : boolean;

      begin
         while (assigned(def1)) and (assigned(def2)) do
           begin
              if value_equal_const then
                begin
                   if not(is_equal(def1^.data,def2^.data)) or
                     ((def1^.paratyp<>def2^.paratyp) and
                      ((def1^.paratyp=vs_var) or
                       (def1^.paratyp=vs_var)
                      )
                     ) then
                     begin
                        equal_paras:=false;
                        exit;
                     end;
                end
              else
                begin
                   if not(is_equal(def1^.data,def2^.data)) or
                     (def1^.paratyp<>def2^.paratyp) then
                     begin
                        equal_paras:=false;
                        exit;
                     end;
                end;
              def1:=def1^.next;
              def2:=def2^.next;
           end;
         if (def1=nil) and (def2=nil) then
           equal_paras:=true
         else
           equal_paras:=false;
      end;

    { returns true, if def uses FPU }
    function is_fpu(def : pdef) : boolean;
      begin
         is_fpu:=(def^.deftype=floatdef) and (pfloatdef(def)^.typ<>f32bit);
      end;

    function is_ordinal(def : pdef) : boolean;

      var
         dt : tbasetype;

      begin
         case def^.deftype of
            orddef : begin
                          dt:=porddef(def)^.typ;
                          is_ordinal:=(dt=s32bit) or (dt=u32bit) or (dt=uchar) or (dt=u8bit) or
                            (dt=s8bit) or (dt=s16bit) or (dt=bool8bit) or (dt=u16bit);
                       end;
            enumdef : is_ordinal:=true;
            else is_ordinal:=false;
         end;
      end;

    function is_signed(def : pdef) : boolean;

      var
         dt : tbasetype;

      begin
         case def^.deftype of
            orddef : begin
                          dt:=porddef(def)^.typ;
                          is_signed:=(dt=s32bit) or (dt=s8bit) or (dt=s16bit);
                       end;
            enumdef : is_signed:=false;
            else internalerror(1001);
         end;
      end;

    { true, if p points to an open array def }
    function is_open_array(p : pdef) : boolean;

      begin
         is_open_array:=(p^.deftype=arraydef) and
                 (parraydef(p)^.lowrange=0) and
                 (parraydef(p)^.highrange=-1);
      end;

    { true if the return value is in accumulator (EAX for i386), D0 for 68k }
    function ret_in_acc(def : pdef) : boolean;

      begin
         ret_in_acc:=(def^.deftype=orddef) or
                     (def^.deftype=pointerdef) or
                     (def^.deftype=enumdef) or
                     ((def^.deftype=procvardef) and
                      ((pprocvardef(def)^.options and pomethodpointer)=0)) or
                     (def^.deftype=classrefdef) or
                     ((def^.deftype=objectdef) and
                      pobjectdef(def)^.isclass
                     ) or
                     ((def^.deftype=setdef) and
                      (psetdef(def)^.settype=smallset)) or
                     ((def^.deftype=floatdef) and
                      (pfloatdef(def)^.typ=f32bit));
      end;

    { true if uses a parameter as return value }
    function ret_in_param(def : pdef) : boolean;

      begin
         ret_in_param:=(def^.deftype=arraydef) or
                       (def^.deftype=stringdef) or
                       ((def^.deftype=procvardef) and
                        ((pprocvardef(def)^.options and pomethodpointer)<>0)) or
                       ((def^.deftype=objectdef) and
                        ((pobjectdef(def)^.options and oois_class)=0)
                       ) or
                       (def^.deftype=recorddef) or
                       ((def^.deftype=setdef) and
                        (psetdef(def)^.settype<>smallset));
      end;

    { true if a const parameter is too large to copy }
    function dont_copy_const_param(def : pdef) : boolean;

      begin
         dont_copy_const_param:=(def^.deftype=arraydef) or
                       (def^.deftype=stringdef) or
                       (def^.deftype=objectdef) or
                       (def^.deftype=formaldef) or
                       (def^.deftype=recorddef) or
                       ((def^.deftype=procvardef) and
                        ((pprocvardef(def)^.options and pomethodpointer)<>0)) or
                       ((def^.deftype=setdef) and
                        (psetdef(def)^.settype<>smallset));
      end;

    procedure testrange(def : pdef;l : longint);

      var
         lv,hv: longint;

      begin
         getrange(def,lv,hv);
         if (def^.deftype=orddef) and
            (porddef(def)^.typ=u32bit) then
           begin
              if lv<=hv then
                begin
                   if (l<lv) or (l>hv) then
                    Message(parser_e_range_check_error);
                end
              else
                { this happens with the wrap around problem  }
                { if lv is positive and hv is over $7ffffff  }
                { so it seems negative                       }
                begin
                   if ((l>=0) and (l<lv)) or
                      ((l<0) and (l>hv)) then
                    Message(parser_e_range_check_error);
                end;
           end
         else if (l<lv) or (l>hv) then
           Message(parser_e_range_check_error);
      end;

    procedure getrange(def : pdef;var l : longint;var h : longint);

      begin
         if def^.deftype=orddef then
           case porddef(def)^.typ of
              s32bit,s16bit,u16bit,s8bit,u8bit :
                begin
                   l:=porddef(def)^.von;
                   h:=porddef(def)^.bis;
                end;
              bool8bit : begin
                            l:=0;
                            h:=1;
                         end;
              uchar : begin
                         l:=0;
                         h:=255;
                      end;
              u32bit : begin
                          { this should work now }
                          l:=porddef(def)^.von;
                          h:=porddef(def)^.bis;
                       end;
           end
         else
           if def^.deftype=enumdef then
             begin
                l:=0;
                h:=penumdef(def)^.max;
             end;
      end;

    function get_ordinal_value(p : ptree) : longint;

      begin
         if p^.treetype=ordconstn then
           get_ordinal_value:=p^.value
         else
           Message(parser_e_ordinal_expected);
      end;

    function mmx_type(p : pdef) : tmmxtype;

      begin
         mmx_type:=mmxno;
         if is_mmx_able_array(p) then
           begin
              if parraydef(p)^.definition^.deftype=floatdef then
                case pfloatdef(parraydef(p)^.definition)^.typ of
                  s32real:
                    mmx_type:=mmxsingle;
                  f16bit:
                    mmx_type:=mmxfixed16
                end
              else
                case porddef(parraydef(p)^.definition)^.typ of
                   u8bit:
                     mmx_type:=mmxu8bit;
                   s8bit:
                     mmx_type:=mmxs8bit;
                   u16bit:
                     mmx_type:=mmxu16bit;
                   s16bit:
                     mmx_type:=mmxs16bit;
                   u32bit:
                     mmx_type:=mmxu32bit;
                   s32bit:
                     mmx_type:=mmxs32bit;
                end;
           end;
      end;

    function is_mmx_able_array(p : pdef) : boolean;

      begin
{$ifdef SUPPORT_MMX}
         if (cs_mmx_saturation in aktswitches) then
           begin
              is_mmx_able_array:=(p^.deftype=arraydef) and
                (
                 ((parraydef(p)^.definition^.deftype=orddef) and
                  (
                  (parraydef(p)^.lowrange=0) and
                  (parraydef(p)^.highrange=1) and
                  (porddef(parraydef(p)^.definition)^.typ in [u32bit,s32bit])
                  ) or
                  (
                  (parraydef(p)^.lowrange=0) and
                  (parraydef(p)^.highrange=3) and
                  (porddef(parraydef(p)^.definition)^.typ in [u16bit,s16bit])
                  )
                 )
                ) or
                (
                 ((parraydef(p)^.definition^.deftype=floatdef) and
                  (
                   (parraydef(p)^.lowrange=0) and
                   (parraydef(p)^.highrange=3) and
                   (pfloatdef(parraydef(p)^.definition)^.typ=f16bit)
                  ) or
                  (
                   (parraydef(p)^.lowrange=0) and
                   (parraydef(p)^.highrange=1) and
                   (pfloatdef(parraydef(p)^.definition)^.typ=s32real)
                  )
                 )
                );
           end
         else
           begin
              is_mmx_able_array:=(p^.deftype=arraydef) and
                (
                 ((parraydef(p)^.definition^.deftype=orddef) and
                  (
                  (parraydef(p)^.lowrange=0) and
                  (parraydef(p)^.highrange=1) and
                  (porddef(parraydef(p)^.definition)^.typ in [u32bit,s32bit])
                  ) or
                  (
                  (parraydef(p)^.lowrange=0) and
                  (parraydef(p)^.highrange=3) and
                  (porddef(parraydef(p)^.definition)^.typ in [u16bit,s16bit])
                  ) or
                  (
                  (parraydef(p)^.lowrange=0) and
                  (parraydef(p)^.highrange=7) and
                  (porddef(parraydef(p)^.definition)^.typ in [u8bit,s8bit])
                  )
                 )
                ) or
                (
                 ((parraydef(p)^.definition^.deftype=floatdef) and
                  (
                   (parraydef(p)^.lowrange=0) and
                   (parraydef(p)^.highrange=3) and
                   (pfloatdef(parraydef(p)^.definition)^.typ=f32bit)
                  )
                  or
                  (
                   (parraydef(p)^.lowrange=0) and
                   (parraydef(p)^.highrange=1) and
                   (pfloatdef(parraydef(p)^.definition)^.typ=s32real)
                  )
                 )
                );
           end;
{$else SUPPORT_MMX}
         is_mmx_able_array:=false;
{$endif SUPPORT_MMX}
      end;

    function is_equal(def1,def2 : pdef) : boolean;

      var
         b : boolean;
         hd : pdef;
         hp1,hp2 : pdefcoll;

      begin
         { both types must exists }
         if not (assigned(def1) and assigned(def2)) then
          begin
            is_equal:=false;
            exit;
          end;

         { be sure, that if there is a stringdef, that this is def1 }
         if def2^.deftype=stringdef then
           begin
              hd:=def1;
              def1:=def2;
              def2:=hd;
           end;
         b:=false;

         { wenn beide auf die gleiche Definition zeigen sind sie wohl gleich...}
         if def1=def2 then
           b:=true
         else
         { pointer with an equal definition are equal }
           if (def1^.deftype=pointerdef) and (def2^.deftype=pointerdef) then
         { here a problem detected in tabsolutesym }
         { the types can be forward type !!        }
             begin
                if assigned(def1^.sym) and ((def1^.sym^.properties and sp_forwarddef)<>0) then
                  b:=(def1^.sym=def2^.sym)
                else
                  b:=is_equal(ppointerdef(def1)^.definition,ppointerdef(def2)^.definition);
             end
         else
         { Grundtypen sind gleich, wenn sie den selben Grundtyp haben, }
         { und wenn noetig den selben Unterbereich haben }
           if (def1^.deftype=orddef) and (def2^.deftype=orddef) then
             begin
                case porddef(def1)^.typ of
                   u32bit,u8bit,s32bit,s8bit,u16bit,s16bit : begin
                                     if porddef(def1)^.typ=porddef(def2)^.typ then
                                       if (porddef(def1)^.von=porddef(def2)^.von) and
                                          (porddef(def1)^.bis=porddef(def2)^.bis) then
                                           b:=true;
                                  end;
                   uvoid,bool8bit,uchar :
                     b:=porddef(def1)^.typ=porddef(def2)^.typ;
                end;
             end
         else
           if (def1^.deftype=floatdef) and (def2^.deftype=floatdef) then
             b:=pfloatdef(def1)^.typ=pfloatdef(def2)^.typ
         else
            { strings with the same length are equal }
            if (def1^.deftype=stringdef) and (def2^.deftype=stringdef) and
               (pstringdef(def1)^.len=pstringdef(def2)^.len) then
            b:=true
    { STRING[N] ist equivalent zu ARRAY[0..N] OF CHAR (N<256) }
{
         else if ((def1^.deftype=stringdef) and (def2^.deftype=arraydef)) and
              (parraydef(def2)^.definition^.deftype=orddef) and
              (porddef(parraydef(def1)^.definition)^.typ=uchar) and
              (parraydef(def2)^.lowrange=0) and
              (parraydef(def2)^.highrange=pstringdef(def1)^.len) then
              b:=true }
          else
            if (def1^.deftype=formaldef) and (def2^.deftype=formaldef) then
              b:=true
          { file types with the same file element type are equal }
          { this is a problem for assign !!                      }
          { changed to allow if one is untyped                   }
          { all typed files are equal to the special             }
          { typed file that has voiddef as elemnt type           }
          { but must NOT match for text file !!!                 }
          else
            if (def1^.deftype=filedef) and (def2^.deftype=filedef) then
              b:=(pfiledef(def1)^.filetype=pfiledef(def2)^.filetype) and
                 ((
                 ((pfiledef(def1)^.typed_as=nil) and
                  (pfiledef(def2)^.typed_as=nil)) or
                 (
                  (pfiledef(def1)^.typed_as<>nil) and
                  (pfiledef(def2)^.typed_as<>nil) and
                  is_equal(pfiledef(def1)^.typed_as,pfiledef(def2)^.typed_as)
                 ) or
                 ( (pfiledef(def1)^.typed_as=pdef(voiddef)) or
                   (pfiledef(def2)^.typed_as=pdef(voiddef))
                 )))
          { sets with the same element type are equal }
          else
            if (def1^.deftype=setdef) and (def2^.deftype=setdef) then
              begin
                 if assigned(psetdef(def1)^.setof) and
                    assigned(psetdef(def2)^.setof) then
                   b:=is_equal(psetdef(def1)^.setof,psetdef(def2)^.setof)
                 else b:=true;
              end
          else
            if (def1^.deftype=procvardef) and (def2^.deftype=procvardef) then
              begin
                 { poassembler isn't important for compatibility }
                 b:=((pprocvardef(def1)^.options and not(poassembler))=
                     (pprocvardef(def2)^.options and not(poassembler))
                    ) and
                   is_equal(pprocvardef(def1)^.retdef,pprocvardef(def2)^.retdef);
                 { now evalute the parameters }
                 if b then
                   begin
                      hp1:=pprocvardef(def1)^.para1;
                      hp2:=pprocvardef(def1)^.para1;
                      while assigned(hp1) and assigned(hp2) do
                        begin
                           if not(is_equal(hp1^.data,hp2^.data)) or
                             not(hp1^.paratyp=hp2^.paratyp) then
                             begin
                                b:=false;
                                break;
                             end;
                           hp1:=hp1^.next;
                           hp2:=hp2^.next;
                        end;
                      b:=(hp1=nil) and (hp2=nil);
                   end;
              end
          else
            if (def1^.deftype=arraydef) and (def2^.deftype=arraydef) and
              (is_open_array(def1) or is_open_array(def2)) then
              begin
                 b:=is_equal(parraydef(def1)^.definition,parraydef(def2)^.definition);
              end
          else
            if (def1^.deftype=classrefdef) and (def2^.deftype=classrefdef) then
              begin
                 { similar to pointerdef: }
                 if assigned(def1^.sym) and ((def1^.sym^.properties and sp_forwarddef)<>0) then
                   b:=(def1^.sym=def2^.sym)
                 else
                   b:=is_equal(pclassrefdef(def1)^.definition,pclassrefdef(def2)^.definition);
              end;
         is_equal:=b;
      end;


    function is_subequal(def1, def2: pdef): boolean;
    Begin
      if assigned(def1) and assigned(def2) then
      Begin
        is_subequal := FALSE;
        if (def1^.deftype = orddef) and (def2^.deftype = orddef) then
          Begin
            { see p.47 of Turbo Pascal 7.01 manual for the separation of types }
            { range checking for case statements is done with testrange        }
            case porddef(def1)^.typ of
              s32bit,u32bit,u8bit,s8bit,s16bit,u16bit:
                Begin
{ PROBABLE CODE GENERATION BUG HERE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! }
{                   if porddef(def2)^.typ in [s32bit,u32bit,u8bit,s8bit,s16bit,u16bit] then
                     is_subequal := TRUE; }
                    if (porddef(def2)^.typ = s32bit) or
                       (porddef(def2)^.typ = u32bit) or
                       (porddef(def2)^.typ = u8bit) or
                       (porddef(def2)^.typ = s8bit) or
                       (porddef(def2)^.typ = s16bit) or
                       (porddef(def2)^.typ = u16bit) then
                     Begin
                       is_subequal:=TRUE;
                     end;
                end;
              bool8bit: if porddef(def2)^.typ = bool8bit then is_subequal := TRUE;
              uchar: if porddef(def2)^.typ = uchar then is_subequal := TRUE;
            end;
          end
        else
          Begin
            { I assume that both enumerations are equal when the first }
            { pointers are equal.                                      }
            if (def1^.deftype = enumdef) and (def2^.deftype =enumdef) then
              Begin
                if penumdef(def1)^.first = penumdef(def2)^.first then
                   is_subequal := TRUE;
              end;
          end;
      end; { endif assigned ... }
    end;

    type
       pprocdefcoll = ^tprocdefcoll;

       tprocdefcoll = record
          next : pprocdefcoll;
          data : pprocdef;
       end;

       psymcoll = ^tsymcoll;

       tsymcoll = record
          next : psymcoll;
          name : pstring;
          data : pprocdefcoll;
       end;

    var
       wurzel : psymcoll;
       nextvirtnumber : longint;
       _c : pobjectdef;
       has_constructor,has_virtual_method : boolean;

    procedure eachsym(sym : psym);{$ifndef FPC}far;{$endif}

      var
         procdefcoll : pprocdefcoll;
         hp : pprocdef;
         symcoll : psymcoll;
         _name : string;
         stored : boolean;

      { creates a new entry in the procsym list }
      procedure newentry;

        begin
           { if not, generate a new symbol item }
           new(symcoll);
           symcoll^.name:=stringdup(sym^.name);
           symcoll^.next:=wurzel;
           symcoll^.data:=nil;
           wurzel:=symcoll;
           hp:=pprocsym(sym)^.definition;

           { inserts all definitions }
           while assigned(hp) do
             begin
                new(procdefcoll);
                procdefcoll^.data:=hp;
                procdefcoll^.next:=symcoll^.data;
                symcoll^.data:=procdefcoll;

                { if it's a virtual method }
                if (hp^.options and povirtualmethod)<>0 then
                  begin
                     { then it gets a number ... }
                     hp^.extnumber:=nextvirtnumber;
                     { and we inc the number }
                     inc(nextvirtnumber);
                     has_virtual_method:=true;
                  end;

                if (hp^.options and poconstructor)<>0 then
                  has_constructor:=true;

                { check, if a method should be overridden }
                if (hp^.options and pooverridingmethod)<>0 then
                  Message1(parser_e_nothing_to_be_overridden,_c^.name^+'.'+_name);
                { next overloaded method }
                hp:=hp^.nextoverloaded;
             end;
        end;

      begin
         { put only sub routines into the VMT }
         if sym^.typ=procsym then
           begin
              _name:=sym^.name;
              symcoll:=wurzel;
              while assigned(symcoll) do
                begin
                   { does the symbol already exist in the list ? }
                   if _name=symcoll^.name^ then
                     begin
                        { walk through all defs of the symbol }
                        hp:=pprocsym(sym)^.definition;
                        while assigned(hp) do
                          begin
                             { compare with all stored definitions }
                             procdefcoll:=symcoll^.data;
                             stored:=false;
                             while assigned(procdefcoll) do
                               begin
                                  { compare parameters }
                                  if equal_paras(procdefcoll^.data^.para1,hp^.para1,false) and
                                     (
                                       ((procdefcoll^.data^.options and povirtualmethod)<>0) or
                                       ((hp^.options and povirtualmethod)<>0)
                                     ) then
                                    begin
                                       { wenn sie gleich sind }
                                       { und eine davon virtual deklariert ist }
                                       { Fehler falls nur eine VIRTUAL }
                                       if (procdefcoll^.data^.options and povirtualmethod)<>
                                          (hp^.options and povirtualmethod) then
                                         begin
                                            { in classes, we hide the old method }
                                            if _c^.isclass then
                                              begin
                                                 { warn only if it is the first time,
                                                   we hide the method }
                                                 if _c=hp^._class then
                                                   Message1(parser_w_should_use_override,_c^.name^+'.'+_name);
                                                 newentry;
                                                 exit;
                                              end
                                            else
                                              begin
                                                 Message1(parser_e_overloaded_are_not_both_virtual,_c^.name^+'.'+_name);
                                              end;
                                         end;

                                       { check, if the overridden directive is set }
                                       { (povirtualmethod is set! }

                                       { class ? }
                                       if _c^.isclass and
                                         ((hp^.options and pooverridingmethod)=0) then
                                         begin
                                            { warn only if it is the first time,
                                              we hide the method }
                                            if _c=hp^._class then
                                              Message1(parser_w_should_use_override,_c^.name^+'.'+_name);
                                            newentry;
                                            exit;
                                         end;

                                       { error, if the return types aren't equal }
                                       if not(is_equal(procdefcoll^.data^.retdef,hp^.retdef)) then
                                         Message1(parser_e_overloaded_methodes_not_same_ret,_c^.name^+'.'+_name);


                                       { the flags have to match      }
                                       { except abstract and override }
                                       if (procdefcoll^.data^.options and not(poabstractmethod or pooverridingmethod))<>
                                         (hp^.options and not(poabstractmethod or pooverridingmethod)) then
                                            Message1(parser_e_header_dont_match_forward,_c^.name^+'.'+_name);

                                       { now set the number }
                                       hp^.extnumber:=procdefcoll^.data^.extnumber;
                                       { and exchange }
                                       procdefcoll^.data:=hp;
                                       stored:=true;
                                    end;
                                  procdefcoll:=procdefcoll^.next;
                               end;
                             { if it isn't saved in the list }
                             { we create a new entry         }
                             if not(stored) then
                               begin
                                  new(procdefcoll);
                                  procdefcoll^.data:=hp;
                                  procdefcoll^.next:=symcoll^.data;
                                  symcoll^.data:=procdefcoll;
                                  { if the method is virtual ... }
                                  if (hp^.options and povirtualmethod)<>0 then
                                    begin
                                       { ... it will get a number }
                                       hp^.extnumber:=nextvirtnumber;
                                       inc(nextvirtnumber);
                                    end;
                                  { check, if a method should be overridden }
                                  if (hp^.options and pooverridingmethod)<>0 then
                                   Message1(parser_e_nothing_to_be_overridden,_c^.name^+'.'+_name);
                               end;
                             hp:=hp^.nextoverloaded;
                          end;
                        exit;
                     end;
                   symcoll:=symcoll^.next;
                end;
             newentry;
           end;
      end;

    procedure genvmt(_class : pobjectdef);

      procedure do_genvmt(p : pobjectdef);

        begin
           { start with the base class }
           if assigned(p^.childof) then
             do_genvmt(p^.childof);

           { walk through all public syms }
           _c:=_class;
{$ifdef tp}
           p^.publicsyms^.foreach(eachsym);
{$else}
           p^.publicsyms^.foreach(@eachsym);
{$endif}
        end;

      var
         symcoll : psymcoll;
         procdefcoll : pprocdefcoll;
         i : longint;

      begin
         wurzel:=nil;
         nextvirtnumber:=0;

         has_constructor:=false;
         has_virtual_method:=false;

         { generates a tree of all used methods }
         do_genvmt(_class);

         if has_virtual_method and not(has_constructor) then
           begin
              exterror:=strpnew(_class^.name^);
              Message(parser_w_virtual_without_constructor);
           end;
         { generates the VMT }

         { walk trough all numbers for virtual methods and search }
         { the method                                             }
         for i:=0 to nextvirtnumber-1 do
           begin
              symcoll:=wurzel;

              { walk trough all symbols }
              while assigned(symcoll) do
                begin

                   { walk trough all methods }
                   procdefcoll:=symcoll^.data;
                   while assigned(procdefcoll) do
                     begin
                        { writes the addresses to the VMT }
                        { but only this which are declared as virtual }
                        if procdefcoll^.data^.extnumber=i then
                          begin
                             if (procdefcoll^.data^.options and povirtualmethod)<>0 then
                               begin
                                  { if a method is abstract, then is also the }
                                  { class abstract and it's not allow to      }
                                  { generates an instance                     }
                                  if (procdefcoll^.data^.options and poabstractmethod)<>0 then
                                    begin
                                       _class^.options:=_class^.options or oois_abstract;
                                       datasegment^.concat(new(pai_const,init_symbol('ABSTRACTERROR')));
                                    end
                                  else
                                    begin
                                      datasegment^.concat(new(pai_const,init_symbol(
                                        strpnew(procdefcoll^.data^.mangledname))));
                                      maybe_concat_external(procdefcoll^.data^.owner,
                                        procdefcoll^.data^.mangledname);
                                    end;
                               end;
                          end;
                        procdefcoll:=procdefcoll^.next;
                     end;
                   symcoll:=symcoll^.next;
                end;
           end;
         { disposes the above generated tree }
         symcoll:=wurzel;
         while assigned(symcoll) do
           begin
              wurzel:=symcoll^.next;
              stringdispose(symcoll^.name);
              procdefcoll:=symcoll^.data;
              while assigned(procdefcoll) do
                begin
                   symcoll^.data:=procdefcoll^.next;
                   dispose(procdefcoll);
                   procdefcoll:=symcoll^.data;
                end;
              dispose(symcoll);
              symcoll:=wurzel;
           end;
      end;

end.
{
  $Log$
  Revision 1.8  1998-04-12 22:39:44  florian
    * problem with read access to properties solved
    * correct handling of hidding methods via virtual (COM)
    * correct result type of constructor calls (COM), the resulttype
      depends now on the type of the class reference

  Revision 1.7  1998/04/10 21:36:56  florian
    + some stuff to support method pointers (procedure of object) added
      (declaration, parameter handling)

  Revision 1.6  1998/04/10 15:39:49  florian
    * more fixes to get classes.pas compiled

  Revision 1.5  1998/04/09 23:02:16  florian
    * small problems solved to get remake3 work

  Revision 1.4  1998/04/08 16:58:09  pierre
    * several bugfixes
      ADD ADC and AND are also sign extended
      nasm output OK (program still crashes at end
      and creates wrong assembler files !!)
      procsym types sym in tdef removed !!

  Revision 1.3  1998/04/08 11:34:22  peter
    * nasm works (linux only tested)

  Revision 1.2  1998/03/28 23:09:57  florian
    * secondin bugfix (m68k and i386)
    * overflow checking bugfix (m68k and i386) -- pretty useless in
      secondadd, since everything is done using 32-bit
    * loading pointer to routines hopefully fixed (m68k)
    * flags problem with calls to RTL internal routines fixed (still strcmp
      to fix) (m68k)
    * #ELSE was still incorrect (didn't take care of the previous level)
    * problem with filenames in the command line solved
    * problem with mangledname solved
    * linking name problem solved (was case insensitive)
    * double id problem and potential crash solved
    * stop after first error
    * and=>test problem removed
    * correct read for all float types
    * 2 sigsegv fixes and a cosmetic fix for Internal Error
    * push/pop is now correct optimized (=> mov (%esp),reg)

  Revision 1.1.1.1  1998/03/25 11:18:15  root
  * Restored version

  Revision 1.24  1998/03/21 23:59:40  florian
    * indexed properties fixed
    * ppu i/o of properties fixed
    * field can be also used for write access
    * overriding of properties

  Revision 1.23  1998/03/20 23:31:35  florian
    * bug0113 fixed
    * problem with interdepened units fixed ("options.pas problem")
    * two small extensions for future AMD 3D support

  Revision 1.22  1998/03/10 01:17:30  peter
    * all files have the same header
    * messages are fully implemented, EXTDEBUG uses Comment()
    + AG... files for the Assembler generation

  Revision 1.21  1998/03/06 01:09:01  peter
    * removed the conflicts that had occured

  Revision 1.20  1998/03/06 00:53:01  peter
    * replaced all old messages from errore.msg, only ExtDebug and some
      Comment() calls are left
    * fixed options.pas

  Revision 1.19  1998/03/05 22:40:56  florian
    + warning about missing constructor added

  Revision 1.18  1998/03/04 17:34:14  michael
  + Changed ifdef FPK to ifdef FPC

  Revision 1.17  1998/03/02 01:49:38  peter
    * renamed target_DOS to target_GO32V1
    + new verbose system, merged old errors and verbose units into one new
      verbose.pas, so errors.pas is obsolete

  Revision 1.16  1998/02/13 10:35:55  daniel
  * Made Motorola version compilable.
  * Fixed optimizer

  Revision 1.15  1998/02/12 17:19:33  florian
    * fixed to get remake3 work, but needs additional fixes (output, I don't like
      also that aktswitches isn't a pointer)

  Revision 1.14  1998/02/12 11:50:52  daniel
  Yes! Finally! After three retries, my patch!

  Changes:

  Complete rewrite of psub.pas.
  Added support for DLL's.
  Compiler requires less memory.
  Platform units for each platform.

  Revision 1.13  1998/02/11 21:56:41  florian
    * bugfixes: bug0093, bug0053, bug0088, bug0087, bug0089

  Revision 1.12  1998/02/07 23:05:08  florian
    * once more MMX

  Revision 1.11  1998/02/06 10:34:35  florian
    * bug0082 and bug0084 fixed

  Revision 1.10  1998/02/05 22:27:07  florian
    * small problems fixed: remake3 should now work

  Revision 1.9  1998/02/05 21:54:36  florian
    + more MMX

  Revision 1.8  1998/01/31 00:43:37  carl
    - removed in in is_subequal, because the code generator is buggy!
      (instead uses if...)

  Revision 1.7  1998/01/16 18:03:21  florian
    * small bug fixes, some stuff of delphi styled constructores added

  Revision 1.6  1998/01/11 19:24:35  carl
    + type checking routine (is_subequal) for case statements

  Revision 1.5  1998/01/09 23:08:38  florian
    + C++/Delphi styled //-comments
    * some bugs in Delphi object model fixed
    + override directive

  Revision 1.4  1998/01/09 16:08:24  florian
    * abstract methods call now abstracterrorproc if they are called
      a class with an abstract method can be create with a class reference else
      the compiler forbides this

  Revision 1.3  1998/01/07 00:17:12  michael
  Restored released version (plus fixes) as current

  Revision 1.2  1997/11/28 18:14:51  pierre
   working version with several bug fixes

  Revision 1.1.1.1  1997/11/27 08:33:03  michael
  FPC Compiler CVS start


  Pre-CVS log:

  CEC   Carl-Eric Codere
  FK    Florian Klaempfl
  PM    Pierre Muller
  +     feature added
  -     removed
  *     bug fixed or changed

  History:
      22th september 1997
         + function dont_copy_const_param added (FK)
      25th september 1997
         + is_open_array added (FK)
         + is_equal handles now also open arrays (FK)
      2nd october 1997
         + added then boolean never_copy_const_param for use in typed write
           where we must push the reference anyway (PM)
      3rd october 1997:
         + renamed ret_in_eax to ret_in_acc (for accumulator for port.) (CEC)
         - removed reference to i386 unit (CEC)
     25th october 1997:
         * poassembler isn't important for compatiblity of proc vars (FK)
      3rd november 1997:
         + added formaldef type to types where we dont_copy_const_param (PM)
      20rd november 1997:
         + added is_fpu function (PM)
}