fpc/compiler/htypechk.pas

{
    Copyright (c) 1998-2002 by Florian Klaempfl

    This unit exports some help routines for the type checking

    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 htypechk;

{$i fpcdefs.inc}

interface

    uses
      cclasses,tokens,cpuinfo,
      node,globtype,
      symconst,symtype,symdef,symsym,symbase;

    type
      Ttok2nodeRec=record
        tok : ttoken;
        nod : tnodetype;
        op_overloading_supported : boolean;
      end;

      pcandidate = ^tcandidate;
      tcandidate = record
         next         : pcandidate;
         data         : tprocdef;
         wrongparaidx,
         firstparaidx : integer;
         exact_count,
         equal_count,
         cl1_count,
         cl2_count,
         cl3_count,
         cl4_count,
         cl5_count,
         coper_count : integer; { should be signed }
         ordinal_distance : double;
         invalid     : boolean;
         wrongparanr : byte;
      end;

      tcallcandidates = class
      private
        FProcsym     : tprocsym;
        FProcsymtable : tsymtable;
        FOperator    : ttoken;
        FCandidateProcs    : pcandidate;
        FProcCnt    : integer;
        FParaNode   : tnode;
        FParaLength : smallint;
        FAllowVariant : boolean;
        procedure collect_overloads_in_class(ProcdefOverloadList:TFPObjectList);
        procedure collect_overloads_in_units(ProcdefOverloadList:TFPObjectList);
        procedure create_candidate_list(ignorevisibility,allowdefaultparas:boolean);
        function  proc_add(ps:tprocsym;pd:tprocdef):pcandidate;
      public
        constructor create(sym:tprocsym;st:TSymtable;ppn:tnode;ignorevisibility,allowdefaultparas:boolean);
        constructor create_operator(op:ttoken;ppn:tnode);
        destructor destroy;override;
        procedure list(all:boolean);
{$ifdef EXTDEBUG}
        procedure dump_info(lvl:longint);
{$endif EXTDEBUG}
        procedure get_information;
        function  choose_best(var bestpd:tabstractprocdef; singlevariant: boolean):integer;
        procedure find_wrong_para;
        property  Count:integer read FProcCnt;
      end;

    type
      tregableinfoflag = (
         // can be put in a register if it's the address of a var/out/const parameter
         ra_addr_regable,
         // orthogonal to above flag: the address of the node is taken and may
         // possibly escape the block in which this node is declared (e.g. a
         // local variable is passed as var parameter to another procedure)
         ra_addr_taken);
      tregableinfoflags = set of tregableinfoflag;

    const
      tok2nodes=24;
      tok2node:array[1..tok2nodes] of ttok2noderec=(
        (tok:_PLUS    ;nod:addn;op_overloading_supported:true),      { binary overloading supported }
        (tok:_MINUS   ;nod:subn;op_overloading_supported:true),      { binary and unary overloading supported }
        (tok:_STAR    ;nod:muln;op_overloading_supported:true),      { binary overloading supported }
        (tok:_SLASH   ;nod:slashn;op_overloading_supported:true),    { binary overloading supported }
        (tok:_EQUAL   ;nod:equaln;op_overloading_supported:true),    { binary overloading supported }
        (tok:_GT      ;nod:gtn;op_overloading_supported:true),       { binary overloading supported }
        (tok:_LT      ;nod:ltn;op_overloading_supported:true),       { binary overloading supported }
        (tok:_GTE     ;nod:gten;op_overloading_supported:true),      { binary overloading supported }
        (tok:_LTE     ;nod:lten;op_overloading_supported:true),      { binary overloading supported }
        (tok:_SYMDIF  ;nod:symdifn;op_overloading_supported:true),   { binary overloading supported }
        (tok:_STARSTAR;nod:starstarn;op_overloading_supported:true), { binary overloading supported }
        (tok:_OP_AS     ;nod:asn;op_overloading_supported:false),     { binary overloading NOT supported }
        (tok:_OP_IN     ;nod:inn;op_overloading_supported:false),     { binary overloading NOT supported }
        (tok:_OP_IS     ;nod:isn;op_overloading_supported:false),     { binary overloading NOT supported }
        (tok:_OP_OR     ;nod:orn;op_overloading_supported:true),     { binary overloading supported }
        (tok:_OP_AND    ;nod:andn;op_overloading_supported:true),    { binary overloading supported }
        (tok:_OP_DIV    ;nod:divn;op_overloading_supported:true),    { binary overloading supported }
        (tok:_OP_NOT    ;nod:notn;op_overloading_supported:true),    { unary overloading supported }
        (tok:_OP_MOD    ;nod:modn;op_overloading_supported:true),    { binary overloading supported }
        (tok:_OP_SHL    ;nod:shln;op_overloading_supported:true),    { binary overloading supported }
        (tok:_OP_SHR    ;nod:shrn;op_overloading_supported:true),    { binary overloading supported }
        (tok:_OP_XOR    ;nod:xorn;op_overloading_supported:true),    { binary overloading supported }
        (tok:_ASSIGNMENT;nod:assignn;op_overloading_supported:true), { unary overloading supported }
        (tok:_UNEQUAL ;nod:unequaln;op_overloading_supported:false)   { binary overloading NOT supported  overload = instead }
      );
    const
      allow_array_constructor : boolean = false;

    function node2opstr(nt:tnodetype):string;

    { check operator args and result type }
    function isbinaryoperatoroverloadable(treetyp:tnodetype;ld:tdef;lt:tnodetype;rd:tdef;rt:tnodetype) : boolean;
    function isoperatoracceptable(pf : tprocdef; optoken : ttoken) : boolean;
    function isunaryoverloaded(var t : tnode) : boolean;
    function isbinaryoverloaded(var t : tnode) : boolean;

    { Register Allocation }
    procedure make_not_regable(p : tnode; how: tregableinfoflags);

    { procvar handling }
    function  is_procvar_load(p:tnode):boolean;
    procedure test_local_to_procvar(from_def:tprocvardef;to_def:tdef);

    { sets varsym varstate field correctly }
    type
      tvarstateflag = (vsf_must_be_valid,vsf_use_hints);
      tvarstateflags = set of tvarstateflag;
    procedure set_varstate(p:tnode;newstate:tvarstate;varstateflags:tvarstateflags);

    { sets the callunique flag, if the node is a vecn, }
    { takes care of type casts etc.                 }
    procedure set_unique(p : tnode);

    function  valid_for_formal_var(p : tnode; report_errors: boolean) : boolean;
    function  valid_for_formal_const(p : tnode; report_errors: boolean) : boolean;
    function  valid_for_var(p:tnode; report_errors: boolean):boolean;
    function  valid_for_assignment(p:tnode; report_errors: boolean):boolean;
    function  valid_for_loopvar(p:tnode; report_errors: boolean):boolean;
    function  valid_for_addr(p : tnode; report_errors: boolean) : boolean;

    function allowenumop(nt:tnodetype):boolean;

    procedure check_hints(const srsym: tsym; const symoptions: tsymoptions);

    procedure check_ranges(const location: tfileposinfo; source: tnode; destdef: tdef);

implementation

    uses
       sysutils,
       systems,constexp,globals,
       cutils,verbose,
       symtable,
       defutil,defcmp,
       nbas,ncnv,nld,nmem,ncal,nmat,ninl,nutils,ncon,
       cgbase,procinfo
       ;

    type
      TValidAssign=(Valid_Property,Valid_Void,Valid_Const,Valid_Addr,Valid_Packed);
      TValidAssigns=set of TValidAssign;


    function node2opstr(nt:tnodetype):string;
      var
        i : integer;
      begin
        result:='<unknown>';
        for i:=1 to tok2nodes do
          if tok2node[i].nod=nt then
            begin
              result:=tokeninfo^[tok2node[i].tok].str;
              break;
            end;
       end;


    function isbinaryoperatoroverloadable(treetyp:tnodetype;ld:tdef;lt:tnodetype;rd:tdef;rt:tnodetype) : boolean;

        function internal_check(treetyp:tnodetype;ld:tdef;lt:tnodetype;rd:tdef;rt:tnodetype;var allowed:boolean):boolean;
        begin
          internal_check:=true;
          case ld.typ of
            formaldef,
            recorddef,
            variantdef :
              begin
                allowed:=true;
              end;
            procvardef :
              begin
                if (rd.typ in [pointerdef,procdef,procvardef]) then
                 begin
                   allowed:=false;
                   exit;
                 end;
                allowed:=true;
              end;
            pointerdef :
              begin
                if ((rd.typ in [orddef,enumdef,pointerdef,classrefdef,procvardef]) or
                    is_class_or_interface_or_objc(rd)) then
                 begin
                   allowed:=false;
                   exit;
                 end;

                { don't allow pchar+string }
                if (is_pchar(ld) or is_pwidechar(ld)) and
                   ((rd.typ=stringdef) or
                    is_pchar(rd) or
                    is_pwidechar(rd) or
                    is_chararray(rd) or
                    is_widechararray(rd)) then
                 begin
                   allowed:=false;
                   exit;
                 end;
                allowed:=true;
              end;
            arraydef :
              begin
                { not vector/mmx }
                if ((cs_mmx in current_settings.localswitches) and
                   is_mmx_able_array(ld)) or
                   ((cs_support_vectors in current_settings.globalswitches) and
                   is_vector(ld)) then
                 begin
                   allowed:=false;
                   exit;
                 end;
                { not chararray+[(wide)char,(wide)string,(wide)chararray] }
                if (is_chararray(ld) or is_widechararray(ld) or
                    is_open_chararray(ld) or is_open_widechararray(ld))
                   and
                   ((rd.typ in [stringdef,orddef,enumdef]) or
                    is_pchar(rd) or
                    is_pwidechar(rd) or
                    is_chararray(rd) or
                    is_widechararray(rd) or
                    is_open_chararray(rd) or
                    is_open_widechararray(rd) or
                    (rt=niln)) then
                 begin
                   allowed:=false;
                   exit;
                 end;
                { dynamic array compare with niln }
                if ((is_dynamic_array(ld) and
                   (rt=niln)) or
                   (is_dynamic_array(ld) and is_dynamic_array(rd)))
                   and
                   (treetyp in [equaln,unequaln]) then
                 begin
                   allowed:=false;
                   exit;
                 end;
                allowed:=true;
              end;
            objectdef :
              begin
                { <> and = are defined for classes }
                if (treetyp in [equaln,unequaln]) and
                   is_class_or_interface_or_objc(ld) then
                 begin
                   allowed:=false;
                   exit;
                 end;
                allowed:=true;
              end;
            stringdef :
              begin
                if (rd.typ in [orddef,enumdef,stringdef]) or
                   is_pchar(rd) or
                   is_pwidechar(rd) or
                   is_chararray(rd) or
                   is_widechararray(rd) or
                   is_open_chararray(rd) or
                   is_open_widechararray(rd) then
                 begin
                   allowed:=false;
                   exit;
                 end;
                allowed:=true;
              end;
            else
              internal_check:=false;
          end;
        end;

      var
        allowed : boolean;
      begin
        { power ** is always possible }
        if (treetyp=starstarn) then
         begin
           isbinaryoperatoroverloadable:=true;
           exit;
         end;
        { order of arguments does not matter so we have to check also
          the reversed order }
        allowed:=false;
        if not internal_check(treetyp,ld,lt,rd,rt,allowed) then
          internal_check(treetyp,rd,rt,ld,lt,allowed);
        isbinaryoperatoroverloadable:=allowed;
      end;


    function isunaryoperatoroverloadable(treetyp : tnodetype;ld : tdef) : boolean;
      begin
        result:=false;
        case treetyp of
          subn,
          unaryminusn :
            begin
              if (ld.typ in [orddef,enumdef,floatdef]) then
                exit;

{$ifdef SUPPORT_MMX}
              if (cs_mmx in current_settings.localswitches) and
                 is_mmx_able_array(ld) then
                exit;
{$endif SUPPORT_MMX}

              result:=true;
            end;

          notn :
            begin
              if (ld.typ in [orddef,enumdef,floatdef]) then
                exit;

{$ifdef SUPPORT_MMX}
              if (cs_mmx in current_settings.localswitches) and
                 is_mmx_able_array(ld) then
                exit;
{$endif SUPPORT_MMX}

              result:=true;
            end;
        end;
      end;


    function isoperatoracceptable(pf : tprocdef; optoken : ttoken) : boolean;
      var
        ld,rd : tdef;
        i : longint;
        eq : tequaltype;
        conv : tconverttype;
        pd : tprocdef;
        oldcount,
        count: longint;
        parasym : tparavarsym;
      begin
        result:=false;
        count := pf.parast.SymList.count;

        oldcount:=count;
        while count > 0 do
          begin
            parasym:=tparavarsym(pf.parast.SymList[count-1]);
            if is_boolean(parasym.vardef) then
              begin
                if parasym.name='RANGECHECK' then
                  begin
                    Include(parasym.varoptions, vo_is_hidden_para);
                    Include(parasym.varoptions, vo_is_range_check);
                    Dec(count);
                  end
                else if parasym.name='OVERFLOWCHECK' then
                  begin
                    Include(parasym.varoptions, vo_is_hidden_para);
                    Include(parasym.varoptions, vo_is_overflow_check);
                    Dec(count);
                  end
                else
                  break;
              end
            else
              break;
          end;
        if count<>oldcount then
          pf.calcparas;

        case count of
          1 : begin
                ld:=tparavarsym(pf.parast.SymList[0]).vardef;
                { assignment is a special case }
                if optoken=_ASSIGNMENT then
                  begin
                    eq:=compare_defs_ext(ld,pf.returndef,nothingn,conv,pd,[cdo_explicit]);
                    result:=
                      (eq=te_incompatible) and
                      { don't allow overloading assigning to custom shortstring
                        types, because we also don't want to differentiate based
                        on different shortstring types (e.g.,
                        "operator :=(const v: variant) res: shorstring" also
                        has to work for assigning a variant to a string[80])
                      }
                      (not is_shortstring(pf.returndef) or
                       (tstringdef(pf.returndef).len=255));
                  end
                else
                  begin
                    for i:=1 to tok2nodes do
                      if tok2node[i].tok=optoken then
                        begin
                          result:=
                            tok2node[i].op_overloading_supported and
                            isunaryoperatoroverloadable(tok2node[i].nod,ld);
                          break;
                        end;
                  end;
              end;
          2 : begin
                for i:=1 to tok2nodes do
                  if tok2node[i].tok=optoken then
                    begin
                      ld:=tparavarsym(pf.parast.SymList[0]).vardef;
                      rd:=tparavarsym(pf.parast.SymList[1]).vardef;
                      result:=
                        tok2node[i].op_overloading_supported and
                        isbinaryoperatoroverloadable(tok2node[i].nod,ld,nothingn,rd,nothingn);
                      break;
                    end;
              end;
        end;
      end;


    function isunaryoverloaded(var t : tnode) : boolean;
      var
        ld      : tdef;
        optoken : ttoken;
        operpd  : tprocdef;
        ppn     : tcallparanode;
        candidates : tcallcandidates;
        cand_cnt : integer;
      begin
        result:=false;
        operpd:=nil;

        { load easier access variables }
        ld:=tunarynode(t).left.resultdef;
        if not isunaryoperatoroverloadable(t.nodetype,ld) then
          exit;

        { operator overload is possible }
        result:=true;

        case t.nodetype of
           notn:
             optoken:=_OP_NOT;
           unaryminusn:
             optoken:=_MINUS;
           else
             begin
               CGMessage(parser_e_operator_not_overloaded);
               t:=cnothingnode.create;
               exit;
             end;
        end;

        { generate parameter nodes }
        ppn:=ccallparanode.create(tunarynode(t).left.getcopy,nil);
        ppn.get_paratype;
        candidates:=tcallcandidates.create_operator(optoken,ppn);

        { stop when there are no operators found }
        if candidates.count=0 then
          begin
            CGMessage(parser_e_operator_not_overloaded);
            candidates.free;
            ppn.free;
            t:=cnothingnode.create;
            exit;
          end;

        { Retrieve information about the candidates }
        candidates.get_information;
{$ifdef EXTDEBUG}
        { Display info when multiple candidates are found }
        candidates.dump_info(V_Debug);
{$endif EXTDEBUG}
        cand_cnt:=candidates.choose_best(operpd,false);

        { exit when no overloads are found }
        if cand_cnt=0 then
          begin
            CGMessage(parser_e_operator_not_overloaded);
            candidates.free;
            ppn.free;
            t:=cnothingnode.create;
            exit;
          end;

        { Multiple candidates left? }
        if cand_cnt>1 then
          begin
            CGMessage(type_e_cant_choose_overload_function);
{$ifdef EXTDEBUG}
            candidates.dump_info(V_Hint);
{$else EXTDEBUG}
            candidates.list(false);
{$endif EXTDEBUG}
            { we'll just use the first candidate to make the
              call }
          end;
        candidates.free;

        addsymref(operpd.procsym);

        { the nil as symtable signs firstcalln that this is
          an overloaded operator }
        t:=ccallnode.create(ppn,Tprocsym(operpd.procsym),nil,nil,[]);

        { we already know the procdef to use, so it can
          skip the overload choosing in callnode.pass_typecheck }
        tcallnode(t).procdefinition:=operpd;
      end;


    function isbinaryoverloaded(var t : tnode) : boolean;
      var
        rd,ld   : tdef;
        optoken : ttoken;
        operpd  : tprocdef;
        ht      : tnode;
        ppn     : tcallparanode;
        candidates : tcallcandidates;
        cand_cnt : integer;
      begin
        isbinaryoverloaded:=false;
        operpd:=nil;
        { load easier access variables }
        ld:=tbinarynode(t).left.resultdef;
        rd:=tbinarynode(t).right.resultdef;
        if not isbinaryoperatoroverloadable(t.nodetype,ld,tbinarynode(t).left.nodetype,rd,tbinarynode(t).right.nodetype) then
          exit;

        { operator overload is possible }
        result:=true;

        case t.nodetype of
           equaln,
           unequaln :
             optoken:=_EQUAL;
           addn:
             optoken:=_PLUS;
           subn:
             optoken:=_MINUS;
           muln:
             optoken:=_STAR;
           starstarn:
             optoken:=_STARSTAR;
           slashn:
             optoken:=_SLASH;
           ltn:
             optoken:=_LT;
           gtn:
             optoken:=_GT;
           lten:
             optoken:=_LTE;
           gten:
             optoken:=_GTE;
           symdifn :
             optoken:=_SYMDIF;
           modn :
             optoken:=_OP_MOD;
           orn :
             optoken:=_OP_OR;
           xorn :
             optoken:=_OP_XOR;
           andn :
             optoken:=_OP_AND;
           divn :
             optoken:=_OP_DIV;
           shln :
             optoken:=_OP_SHL;
           shrn :
             optoken:=_OP_SHR;
           else
             begin
               CGMessage(parser_e_operator_not_overloaded);
               t:=cnothingnode.create;
               exit;
             end;
        end;

        { generate parameter nodes }
        ppn:=ccallparanode.create(tbinarynode(t).right.getcopy,ccallparanode.create(tbinarynode(t).left.getcopy,nil));
        ppn.get_paratype;
        candidates:=tcallcandidates.create_operator(optoken,ppn);

        { for commutative operators we can swap arguments and try again }
        if (candidates.count=0) and
           not(optoken in [_OP_SHL,_OP_SHR,_OP_DIV,_OP_MOD,_STARSTAR,_SLASH,_MINUS]) then
          begin
            candidates.free;
            reverseparameters(ppn);
            { reverse compare operators }
            case optoken of
              _LT:
                optoken:=_GTE;
              _GT:
                optoken:=_LTE;
              _LTE:
                optoken:=_GT;
              _GTE:
                optoken:=_LT;
            end;
            candidates:=tcallcandidates.create_operator(optoken,ppn);
          end;

        { stop when there are no operators found }
        if candidates.count=0 then
          begin
            CGMessage(parser_e_operator_not_overloaded);
            candidates.free;
            ppn.free;
            t:=cnothingnode.create;
            exit;
          end;

        { Retrieve information about the candidates }
        candidates.get_information;
{$ifdef EXTDEBUG}
        { Display info when multiple candidates are found }
        candidates.dump_info(V_Debug);
{$endif EXTDEBUG}
        cand_cnt:=candidates.choose_best(operpd,false);

        { exit when no overloads are found }
        if cand_cnt=0 then
          begin
            CGMessage(parser_e_operator_not_overloaded);
            candidates.free;
            ppn.free;
            t:=cnothingnode.create;
            exit;
          end;

        { Multiple candidates left? }
        if cand_cnt>1 then
          begin
            CGMessage(type_e_cant_choose_overload_function);
{$ifdef EXTDEBUG}
            candidates.dump_info(V_Hint);
{$else EXTDEBUG}
            candidates.list(false);
{$endif EXTDEBUG}
            { we'll just use the first candidate to make the
              call }
          end;
        candidates.free;

        addsymref(operpd.procsym);

        { the nil as symtable signs firstcalln that this is
          an overloaded operator }
        ht:=ccallnode.create(ppn,Tprocsym(operpd.procsym),nil,nil,[]);

        { we already know the procdef to use, so it can
          skip the overload choosing in callnode.pass_typecheck }
        tcallnode(ht).procdefinition:=operpd;

        if t.nodetype=unequaln then
          ht:=cnotnode.create(ht);
        t:=ht;
      end;


{****************************************************************************
                          Register Calculation
****************************************************************************}

    { marks an lvalue as "unregable" }
    procedure make_not_regable_intern(p : tnode; how: tregableinfoflags; records_only: boolean);
      var
        update_regable: boolean;
      begin
        update_regable:=true;
        repeat
          case p.nodetype of
            subscriptn:
              begin
                records_only:=true;
                p:=tsubscriptnode(p).left;
              end;
            vecn:
              begin
                { arrays are currently never regable and pointers indexed like }
                { arrays do not have be made unregable, but we do need to      }
                { propagate the ra_addr_taken info                             }
                update_regable:=false;
                p:=tvecnode(p).left;
              end;
            typeconvn :
               begin
                 if (ttypeconvnode(p).resultdef.typ = recorddef) then
                   records_only:=false;
                 p:=ttypeconvnode(p).left;
               end;
            loadn :
              begin
                if (tloadnode(p).symtableentry.typ in [staticvarsym,localvarsym,paravarsym]) then
                  begin
                    if (ra_addr_taken in how) then
                      tabstractvarsym(tloadnode(p).symtableentry).addr_taken:=true;
                    if update_regable and
                       (tabstractvarsym(tloadnode(p).symtableentry).varregable <> vr_none) and
                       ((not records_only) or
                        (tabstractvarsym(tloadnode(p).symtableentry).vardef.typ = recorddef)) then
                      if (tloadnode(p).symtableentry.typ = paravarsym) and
                         (ra_addr_regable in how) then
                        tabstractvarsym(tloadnode(p).symtableentry).varregable:=vr_addr
                      else
                        tabstractvarsym(tloadnode(p).symtableentry).varregable:=vr_none;
                  end;
                break;
              end;
            temprefn :
              begin
                if (ra_addr_taken in how) then
                  include(ttemprefnode(p).tempinfo^.flags,ti_addr_taken);
                if update_regable and
                   (ti_may_be_in_reg in ttemprefnode(p).tempinfo^.flags) and
                   ((not records_only) or
                    (ttemprefnode(p).tempinfo^.typedef.typ = recorddef)) then
                  exclude(ttemprefnode(p).tempinfo^.flags,ti_may_be_in_reg);
                break;
              end;
            else
              break;
          end;
        until false;
      end;

    procedure make_not_regable(p : tnode; how: tregableinfoflags);
      begin
        make_not_regable_intern(p,how,false);
      end;


{****************************************************************************
                          Subroutine Handling
****************************************************************************}

    function is_procvar_load(p:tnode):boolean;
      begin
        result:=false;
        { remove voidpointer typecast for tp procvars }
        if ((m_tp_procvar in current_settings.modeswitches) or
            (m_mac_procvar in current_settings.modeswitches)) and
           (p.nodetype=typeconvn) and
           is_voidpointer(p.resultdef) then
          p:=tunarynode(p).left;
        result:=(p.nodetype=typeconvn) and
                (ttypeconvnode(p).convtype=tc_proc_2_procvar);
      end;


    { local routines can't be assigned to procvars }
    procedure test_local_to_procvar(from_def:tprocvardef;to_def:tdef);
      begin
         if (from_def.parast.symtablelevel>normal_function_level) and
            (to_def.typ=procvardef) then
           CGMessage(type_e_cannot_local_proc_to_procvar);
      end;


    procedure set_varstate(p:tnode;newstate:tvarstate;varstateflags:tvarstateflags);
      const
        vstrans: array[tvarstate,tvarstate] of tvarstate = (
          { vs_none -> ... }
          (vs_none,vs_declared,vs_initialised,vs_read,vs_read_not_warned,vs_referred_not_inited,vs_written,vs_readwritten),
          { vs_declared -> ... }
          (vs_none,vs_declared,vs_initialised,vs_read,vs_read_not_warned,vs_referred_not_inited,vs_written,vs_readwritten),
          { vs_initialised -> ... }
          (vs_none,vs_initialised,vs_initialised,vs_read,vs_read,vs_read,vs_written,vs_readwritten),
          { vs_read -> ... }
          (vs_none,vs_read,vs_read,vs_read,vs_read,vs_read,vs_readwritten,vs_readwritten),
          { vs_read_not_warned -> ... }
          (vs_none,vs_read_not_warned,vs_read,vs_read,vs_read_not_warned,vs_read_not_warned,vs_readwritten,vs_readwritten),
          { vs_referred_not_inited }
          (vs_none,vs_referred_not_inited,vs_read,vs_read,vs_read_not_warned,vs_referred_not_inited,vs_written,vs_readwritten),
          { vs_written -> ... }
          (vs_none,vs_written,vs_written,vs_readwritten,vs_readwritten,vs_written,vs_written,vs_readwritten),
          { vs_readwritten -> ... }
          (vs_none,vs_readwritten,vs_readwritten,vs_readwritten,vs_readwritten,vs_readwritten,vs_readwritten,vs_readwritten));
      var
        hsym : tabstractvarsym;
      begin
        { make sure we can still warn about uninitialised use after high(v), @v etc }
        if (newstate = vs_read) and
           not(vsf_must_be_valid in varstateflags) then
          newstate := vs_referred_not_inited;

        while assigned(p) do
         begin
           case p.nodetype of
             derefn:
               begin
                 if (tderefnode(p).left.nodetype=temprefn) and
                    assigned(ttemprefnode(tderefnode(p).left).tempinfo^.withnode) then
                   p:=ttemprefnode(tderefnode(p).left).tempinfo^.withnode
                 else
                   break;
               end;
             typeconvn :
               begin
                 case ttypeconvnode(p).convtype of
                   tc_cchar_2_pchar,
                   tc_cstring_2_pchar,
                   tc_array_2_pointer :
                     exclude(varstateflags,vsf_must_be_valid);
                   tc_pchar_2_string,
                   tc_pointer_2_array :
                     include(varstateflags,vsf_must_be_valid);
                 end;
                 p:=tunarynode(p).left;
               end;
             subscriptn :
               begin
                 if is_class_or_interface_or_objc(tunarynode(p).left.resultdef) then
                   newstate := vs_read;
                 p:=tunarynode(p).left;
               end;
             vecn:
               begin
                 set_varstate(tbinarynode(p).right,vs_read,[vsf_must_be_valid]);
                 if (newstate in [vs_read,vs_readwritten]) or
                    not(tunarynode(p).left.resultdef.typ in [stringdef,arraydef]) then
                   include(varstateflags,vsf_must_be_valid)
                 else if (newstate = vs_written) then
                   exclude(varstateflags,vsf_must_be_valid);
                 p:=tunarynode(p).left;
               end;
             { do not parse calln }
             calln :
               break;
             loadn :
               begin
                 if (tloadnode(p).symtableentry.typ in [localvarsym,paravarsym,staticvarsym]) then
                   begin
                     hsym:=tabstractvarsym(tloadnode(p).symtableentry);
                     if (vsf_must_be_valid in varstateflags) and
                        (hsym.varstate in [vs_declared,vs_read_not_warned,vs_referred_not_inited]) then
                       begin
                         { Give warning/note for uninitialized locals }
                         if assigned(hsym.owner) and
                           not(cs_opt_nodedfa in current_settings.optimizerswitches) and
                            not(vo_is_external in hsym.varoptions) and
                            (hsym.owner.symtabletype in [parasymtable,localsymtable,staticsymtable]) and
                            ((hsym.owner=current_procinfo.procdef.localst) or
                             (hsym.owner=current_procinfo.procdef.parast)) then
                           begin
                             if (vo_is_funcret in hsym.varoptions) then
                               begin
                                 if (vsf_use_hints in varstateflags) then
                                   CGMessagePos(p.fileinfo,sym_h_function_result_uninitialized)
                                 else
                                   CGMessagePos(p.fileinfo,sym_w_function_result_uninitialized)
                               end
                             else
                               begin
                                 if tloadnode(p).symtable.symtabletype=localsymtable then
                                   begin
                                     if (vsf_use_hints in varstateflags) then
                                       CGMessagePos1(p.fileinfo,sym_h_uninitialized_local_variable,hsym.realname)
                                     else
                                       CGMessagePos1(p.fileinfo,sym_w_uninitialized_local_variable,hsym.realname);
                                   end
                                 else
                                   begin
                                     if (vsf_use_hints in varstateflags) then
                                       CGMessagePos1(p.fileinfo,sym_h_uninitialized_variable,hsym.realname)
                                     else
                                       CGMessagePos1(p.fileinfo,sym_w_uninitialized_variable,hsym.realname);
                                   end;
                               end;
                           end
                         else if (newstate = vs_read) then
                           newstate := vs_read_not_warned;
                       end;
                     hsym.varstate := vstrans[hsym.varstate,newstate];
                   end;
                 case newstate of
                   vs_written:
                     include(tloadnode(p).flags,nf_write);
                   vs_readwritten:
                     if not(nf_write in tloadnode(p).flags) then
                       include(tloadnode(p).flags,nf_modify);
                 end;
                 break;
               end;
             callparan :
               internalerror(200310081);
             else
               break;
           end;{case }
         end;
      end;


    procedure set_unique(p : tnode);
      begin
        while assigned(p) do
         begin
           case p.nodetype of
             vecn:
               begin
                 include(p.flags,nf_callunique);
                 break;
               end;
             typeconvn,
             subscriptn,
             derefn:
               p:=tunarynode(p).left;
             else
               break;
           end;
         end;
      end;


    function  valid_for_assign(p:tnode;opts:TValidAssigns; report_errors: boolean):boolean;
      var
        hp2,
        hp : tnode;
        gotstring,
        gotsubscript,
        gotrecord,
        gotpointer,
        gotvec,
        gotclass,
        gotdynarray,
        gotderef,
        gottypeconv : boolean;
        fromdef,
        todef    : tdef;
        errmsg,
        temp     : longint;
      begin
        if valid_const in opts then
          errmsg:=type_e_variable_id_expected
        else if valid_property in opts then
          errmsg:=type_e_argument_cant_be_assigned
        else
          errmsg:=type_e_no_addr_of_constant;
        result:=false;
        gotsubscript:=false;
        gotvec:=false;
        gotderef:=false;
        gotrecord:=false;
        gotclass:=false;
        gotpointer:=false;
        gotdynarray:=false;
        gotstring:=false;
        gottypeconv:=false;
        hp:=p;
        if not(valid_void in opts) and
           is_void(hp.resultdef) then
         begin
           if report_errors then
             CGMessagePos(hp.fileinfo,errmsg);
           exit;
         end;
        while assigned(hp) do
         begin
           { property allowed? calln has a property check itself }
           if (nf_isproperty in hp.flags) then
             begin
               { check return type }
               case hp.resultdef.typ of
                 pointerdef :
                   gotpointer:=true;
                 objectdef :
                   gotclass:=is_class_or_interface_or_objc(hp.resultdef);
                 recorddef :
                   gotrecord:=true;
                 classrefdef :
                   gotclass:=true;
                 stringdef :
                   gotstring:=true;
               end;
               if (valid_property in opts) then
                 begin
                   { don't allow writing to calls that will create
                     temps like calls that return a structure and we
                     are assigning to a member }
                   if (valid_const in opts) or
                      { if we got a deref, we won't modify the property itself }
                      (gotderef) or
                      { same when we got a class and subscript (= deref) }
                      (gotclass and gotsubscript) or
                      (
                       { allowing assignments to typecasted properties
                           a) is Delphi-incompatible
                           b) causes problems in case the getter is a function
                              (because then the result of the getter is
                               typecasted to this type, and then we "assign" to
                               this typecasted function result) -> always
                               disallow, since property accessors should be
                               transparantly changeable to functions at all
                               times
                       }
                       not(gottypeconv) and
                       not(gotsubscript and gotrecord) and
                       not(gotstring and gotvec)
                      ) then
                     result:=true
                   else
                     if report_errors then
                       CGMessagePos(hp.fileinfo,errmsg);
                 end
               else
                 begin
                   { 1. if it returns a pointer and we've found a deref,
                     2. if it returns a class or record and a subscription or with is found
                     3. if the address is needed of a field (subscriptn, vecn) }
                   if (gotpointer and gotderef) or
                      (gotstring and gotvec) or
                      (
                       (gotclass or gotrecord) and
                       (gotsubscript)
                      ) or
                      (
                        (gotvec and gotdynarray)
                      ) or
                      (
                       (Valid_Addr in opts) and
                       (hp.nodetype in [subscriptn,vecn])
                      ) then
                     result:=true
                   else
                     if report_errors then
                       CGMessagePos(hp.fileinfo,errmsg);
                 end;
               exit;
             end;
           case hp.nodetype of
             temprefn :
               begin
                 valid_for_assign := true;
                 exit;
               end;
             derefn :
               begin
                 gotderef:=true;
                 hp:=tderefnode(hp).left;
               end;
             typeconvn :
               begin
                 gottypeconv:=true;
                 { typecast sizes must match, exceptions:
                   - implicit typecast made by absolute
                   - from formaldef
                   - from void
                   - from/to open array
                   - typecast from pointer to array }
                 fromdef:=ttypeconvnode(hp).left.resultdef;
                 todef:=hp.resultdef;
                 if not((nf_absolute in ttypeconvnode(hp).flags) or
                        (fromdef.typ=formaldef) or
                        is_void(fromdef) or
                        is_open_array(fromdef) or
                        is_open_array(todef) or
                        ((fromdef.typ=pointerdef) and (todef.typ=arraydef)) or
                        ((fromdef.typ = objectdef) and (todef.typ = objectdef) and
                         (tobjectdef(fromdef).is_related(tobjectdef(todef))))) and
                    (fromdef.size<>todef.size) then
                  begin
                    { in TP it is allowed to typecast to smaller types. But the variable can't
                      be in a register }
                    if (m_tp7 in current_settings.modeswitches) or
                       (todef.size<fromdef.size) then
                      make_not_regable(hp,[ra_addr_regable])
                    else
                      if report_errors then
                        CGMessagePos2(hp.fileinfo,type_e_typecast_wrong_size_for_assignment,tostr(fromdef.size),tostr(todef.size));
                  end;

                 { don't allow assignments to typeconvs that need special code }
                 if not(gotsubscript or gotvec or gotderef) and
                    not(ttypeconvnode(hp).assign_allowed) then
                   begin
                     if report_errors then
                       CGMessagePos(hp.fileinfo,errmsg);
                     exit;
                   end;
                 case hp.resultdef.typ of
                   pointerdef :
                     gotpointer:=true;
                   objectdef :
                     gotclass:=is_class_or_interface_or_objc(hp.resultdef);
                   classrefdef :
                     gotclass:=true;
                   arraydef :
                     begin
                       { pointer -> array conversion is done then we need to see it
                         as a deref, because a ^ is then not required anymore }
                       if (ttypeconvnode(hp).left.resultdef.typ=pointerdef) then
                        gotderef:=true;
                     end;
                 end;
                 hp:=ttypeconvnode(hp).left;
               end;
             vecn :
               begin
                 if { only check for first (= outermost) vec node }
                    not gotvec and
                    not(valid_packed in opts) and
                    (tvecnode(hp).left.resultdef.typ = arraydef) and
                    (ado_IsBitPacked in tarraydef(tvecnode(hp).left.resultdef).arrayoptions) and
                    ((tarraydef(tvecnode(hp).left.resultdef).elepackedbitsize mod 8 <> 0) or
                     (is_ordinal(tarraydef(tvecnode(hp).left.resultdef).elementdef) and
                      not ispowerof2(tarraydef(tvecnode(hp).left.resultdef).elepackedbitsize div 8,temp))) then
                   begin
                     if report_errors then
                       if (valid_property in opts) then
                         CGMessagePos(hp.fileinfo,parser_e_packed_element_no_loop)
                       else
                         CGMessagePos(hp.fileinfo,parser_e_packed_element_no_var_addr);
                     exit;
                   end;
                 gotvec:=true;
                 { accesses to dyn. arrays override read only access in delphi }
                 if (m_delphi in current_settings.modeswitches) and is_dynamic_array(tunarynode(hp).left.resultdef) then
                   gotdynarray:=true;
                 hp:=tunarynode(hp).left;
               end;
             blockn :
               begin
                 hp2:=tblocknode(hp).statements;
                 if assigned(hp2) then
                   begin
                     if hp2.nodetype<>statementn then
                       internalerror(2006110801);
                     while assigned(tstatementnode(hp2).next) do
                       hp2:=tstatementnode(hp2).next;
                     hp:=tstatementnode(hp2).statement;
                   end
                 else
                   begin
                     if report_errors then
                      CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                     exit;
                   end;
               end;
             asn :
               begin
                 { asn can't be assigned directly, it returns the value in a register instead
                   of reference. }
                 if not(gotsubscript or gotderef or gotvec) then
                   begin
                     if report_errors then
                       CGMessagePos(hp.fileinfo,errmsg);
                     exit;
                   end;
                 hp:=tunarynode(hp).left;
               end;
             subscriptn :
               begin
                 { only check first (= outermost) subscriptn }
                 if not gotsubscript and
                    not(valid_packed in opts) and
                    is_packed_record_or_object(tsubscriptnode(hp).left.resultdef) and
                    ((tsubscriptnode(hp).vs.fieldoffset mod 8 <> 0) or
                     (is_ordinal(tsubscriptnode(hp).resultdef) and
                      not ispowerof2(tsubscriptnode(hp).resultdef.packedbitsize div 8,temp)))  then
                   begin
                     if report_errors then
                       if (valid_property in opts) then
                         CGMessagePos(hp.fileinfo,parser_e_packed_element_no_loop)
                       else
                         CGMessagePos(hp.fileinfo,parser_e_packed_element_no_var_addr);
                     exit;
                   end;
                 gotsubscript:=true;
                 { loop counter? }
                 if not(Valid_Const in opts) and
                    (vo_is_loop_counter in tsubscriptnode(hp).vs.varoptions) then
                   begin
                     if report_errors then
                       CGMessage1(parser_e_illegal_assignment_to_count_var,tsubscriptnode(hp).vs.realname)
                     else
                       exit;
                   end;
                 { a class/interface access is an implicit }
                 { dereferencing                           }
                 hp:=tsubscriptnode(hp).left;
                 if is_class_or_interface_or_objc(hp.resultdef) then
                   gotderef:=true;
               end;
             muln,
             divn,
             andn,
             xorn,
             orn,
             notn,
             subn,
             addn :
               begin
                 { Allow operators on a pointer, or an integer
                   and a pointer typecast and deref has been found }
                 if ((hp.resultdef.typ=pointerdef) or
                     (is_integer(hp.resultdef) and gotpointer)) and
                    gotderef then
                  result:=true
                 else
                 { Temp strings are stored in memory, for compatibility with
                   delphi only }
                   if (m_delphi in current_settings.modeswitches) and
                      ((valid_addr in opts) or
                       (valid_const in opts)) and
                      (hp.resultdef.typ=stringdef) then
                     result:=true
                 else
                  if report_errors then
                   CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                 exit;
               end;
             niln,
             pointerconstn :
               begin
                 { to support e.g. @tmypointer(0)^.data; see tests/tbs/tb0481 }
                 if gotderef then
                  result:=true
                 else
                  if report_errors then
                   CGMessagePos(hp.fileinfo,type_e_no_assign_to_addr);
                 exit;
               end;
             ordconstn,
             realconstn :
               begin
                 { these constants will be passed by value }
                 if report_errors then
                   CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                 exit;
               end;
             setconstn,
             stringconstn,
             guidconstn :
               begin
                 { these constants will be passed by reference }
                 if valid_const in opts then
                   result:=true
                 else
                   if report_errors then
                     CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                 exit;
               end;
             addrn :
               begin
                 if gotderef then
                  result:=true
                 else
                  if report_errors then
                   CGMessagePos(hp.fileinfo,type_e_no_assign_to_addr);
                 exit;
               end;
             calln :
               begin
                 { check return type }
                 case hp.resultdef.typ of
                   arraydef :
                     begin
                       { dynamic arrays are allowed when there is also a
                         vec node }
                       if is_dynamic_array(hp.resultdef) and
                          gotvec then
                        begin
                          gotderef:=true;
                          gotpointer:=true;
                        end;
                     end;
                   pointerdef :
                     gotpointer:=true;
                   objectdef :
                     gotclass:=is_class_or_interface_or_objc(hp.resultdef);
                   recorddef, { handle record like class it needs a subscription }
                   classrefdef :
                     gotclass:=true;
                   stringdef :
                     gotstring:=true;
                 end;
                 { 1. if it returns a pointer and we've found a deref,
                   2. if it returns a class or record and a subscription or with is found
                   3. string is returned }
                 if (gotstring and gotvec) or
                    (gotpointer and gotderef) or
                    (gotclass and gotsubscript) then
                  result:=true
                 else
                 { Temp strings are stored in memory, for compatibility with
                   delphi only }
                   if (m_delphi in current_settings.modeswitches) and
                      (valid_addr in opts) and
                      (hp.resultdef.typ=stringdef) then
                     result:=true
                 else
                   if ([valid_const,valid_addr] * opts = [valid_const]) then
                     result:=true
                 else
                  if report_errors then
                   CGMessagePos(hp.fileinfo,errmsg);
                 exit;
               end;
             inlinen :
               begin
                 if ((valid_const in opts) and
                    (tinlinenode(hp).inlinenumber in [in_typeof_x]))
{$ifdef SUPPORT_UNALIGNED}
                    or (tinlinenode(hp).inlinenumber in [in_unaligned_x])
{$endif SUPPORT_UNALIGNED}
                    then
                   result:=true
                 else
                   if report_errors then
                    CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                 exit;
               end;
             dataconstn:
               begin
                 { only created internally, so no additional checks necessary }
                 result:=true;
                 exit;
               end;
             loadn :
               begin
                 case tloadnode(hp).symtableentry.typ of
                   absolutevarsym,
                   staticvarsym,
                   localvarsym,
                   paravarsym :
                     begin
                       { loop counter? }
                       if not(Valid_Const in opts) and
                          not gotderef and
                          (vo_is_loop_counter in tabstractvarsym(tloadnode(hp).symtableentry).varoptions) then
                         if report_errors then
                          CGMessage1(parser_e_illegal_assignment_to_count_var,tloadnode(hp).symtableentry.realname)
                         else
                          exit;
                       { read-only variable? }
                       if (tabstractvarsym(tloadnode(hp).symtableentry).varspez=vs_const) then
                        begin
                          { allow p^:= constructions with p is const parameter }
                          if gotderef or gotdynarray or (Valid_Const in opts) or
                            (nf_isinternal_ignoreconst in tloadnode(hp).flags) then
                            result:=true
                          else
                            if report_errors then
                              CGMessagePos(tloadnode(hp).fileinfo,type_e_no_assign_to_const);
                          exit;
                        end;
                       result:=true;
                       exit;
                     end;
                   procsym :
                     begin
                       if (Valid_Const in opts) then
                         result:=true
                       else
                         if report_errors then
                          CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                       exit;
                     end;
                   labelsym :
                     begin
                       if (Valid_Addr in opts) then
                         result:=true
                       else
                         if report_errors then
                          CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                       exit;
                     end;
                   constsym:
                     begin
                       if (tconstsym(tloadnode(hp).symtableentry).consttyp=constresourcestring) and
                         (valid_addr in opts) then
                         result:=true
                       else
                         if report_errors then
                          CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                       exit;
                     end;
                   else
                     begin
                       if report_errors then
                        CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                       exit;
                     end;
                 end;
               end;
             else
               begin
                 if report_errors then
                  CGMessagePos(hp.fileinfo,type_e_variable_id_expected);
                 exit;
               end;
            end;
         end;
      end;


    function  valid_for_var(p:tnode; report_errors: boolean):boolean;
      begin
        valid_for_var:=valid_for_assign(p,[],report_errors);
      end;


    function  valid_for_formal_var(p : tnode; report_errors: boolean) : boolean;
      begin
        valid_for_formal_var:=valid_for_assign(p,[valid_void],report_errors);
      end;


    function  valid_for_formal_const(p : tnode; report_errors: boolean) : boolean;
      begin
        valid_for_formal_const:=(p.resultdef.typ=formaldef) or
          valid_for_assign(p,[valid_void,valid_const,valid_property],report_errors);
      end;


    function  valid_for_assignment(p:tnode; report_errors: boolean):boolean;
      begin
        valid_for_assignment:=valid_for_assign(p,[valid_property,valid_packed],report_errors);
      end;


    function  valid_for_loopvar(p:tnode; report_errors: boolean):boolean;
      begin
        valid_for_loopvar:=valid_for_assign(p,[valid_property],report_errors);
      end;


    function  valid_for_addr(p : tnode; report_errors: boolean) : boolean;
      begin
        result:=valid_for_assign(p,[valid_const,valid_addr,valid_void],report_errors);
      end;


    procedure var_para_allowed(var eq:tequaltype;def_from,def_to:Tdef; fromnode: tnode);
      begin
        { Note: eq must be already valid, it will only be updated! }
        case def_to.typ of
          formaldef :
            begin
              { all types can be passed to a formaldef,
                but it is not the prefered way }
              if not is_constnode(fromnode) then
                eq:=te_convert_l2
              else
                eq:=te_incompatible;
            end;
          orddef :
            begin
              { allows conversion from word to integer and
                byte to shortint, but only for TP7 compatibility }
              if (m_tp7 in current_settings.modeswitches) and
                 (def_from.typ=orddef) and
                 (def_from.size=def_to.size) then
                eq:=te_convert_l1;
            end;
          arraydef :
            begin
              if is_open_array(def_to) then
                begin
                  if is_dynamic_array(def_from) and
                     equal_defs(tarraydef(def_from).elementdef,tarraydef(def_to).elementdef) then
                    eq:=te_convert_l2
                  else
                    if equal_defs(def_from,tarraydef(def_to).elementdef) then
                      eq:=te_convert_l2;
                end;
            end;
          pointerdef :
            begin
              { an implicit pointer conversion is allowed }
              if (def_from.typ=pointerdef) then
                eq:=te_convert_l1;
            end;
          stringdef :
            begin
              { all shortstrings are allowed, size is not important }
              if is_shortstring(def_from) and
                 is_shortstring(def_to) then
                eq:=te_equal;
            end;
          objectdef :
            begin
              { child objects can be also passed }
              { in non-delphi mode, otherwise    }
              { they must match exactly, except  }
              { if they are objects              }
              if (def_from.typ=objectdef) and
                 (
                  (
                   not(m_delphi in current_settings.modeswitches) and
                   (tobjectdef(def_from).objecttype in [odt_object,odt_class]) and
                   (tobjectdef(def_to).objecttype in [odt_object,odt_class])
                  ) or
                  (
                   (m_delphi in current_settings.modeswitches) and
                   (tobjectdef(def_from).objecttype=odt_object) and
                   (tobjectdef(def_to).objecttype=odt_object)
                  )
                 ) and
                 (tobjectdef(def_from).is_related(tobjectdef(def_to))) then
                eq:=te_convert_l1;
            end;
          filedef :
            begin
              { an implicit file conversion is also allowed }
              { from a typed file to an untyped one           }
              if (def_from.typ=filedef) and
                 (tfiledef(def_from).filetyp = ft_typed) and
                 (tfiledef(def_to).filetyp = ft_untyped) then
                eq:=te_convert_l1;
            end;
        end;
      end;


    procedure para_allowed(var eq:tequaltype;p:tcallparanode;def_to:tdef);
      begin
        { Note: eq must be already valid, it will only be updated! }
        case def_to.typ of
          formaldef :
            begin
              { all types can be passed to a formaldef }
              eq:=te_equal;
            end;
          stringdef :
            begin
              { to support ansi/long/wide strings in a proper way }
              { string and string[10] are assumed as equal }
              { when searching the correct overloaded procedure   }
              if (p.resultdef.typ=stringdef) and
                 (tstringdef(def_to).stringtype=tstringdef(p.resultdef).stringtype) then
                eq:=te_equal
              else
              { Passing a constant char to ansistring or shortstring or
                a widechar to widestring then handle it as equal. }
               if (p.left.nodetype=ordconstn) and
                  (
                   is_char(p.resultdef) and
                   (is_shortstring(def_to) or is_ansistring(def_to))
                  ) or
                  (
                   is_widechar(p.resultdef) and
                   (is_widestring(def_to) or is_unicodestring(def_to))
                  ) then
                eq:=te_equal
            end;
          setdef :
            begin
              { set can also be a not yet converted array constructor }
              if (p.resultdef.typ=arraydef) and
                 is_array_constructor(p.resultdef) and
                 not is_variant_array(p.resultdef) then
                eq:=te_equal;
            end;
          procvardef :
            begin
              { in tp7 mode proc -> procvar is allowed }
              if ((m_tp_procvar in current_settings.modeswitches) or
                  (m_mac_procvar in current_settings.modeswitches)) and
                 (p.left.nodetype=calln) and
                 (proc_to_procvar_equal(tprocdef(tcallnode(p.left).procdefinition),tprocvardef(def_to))>=te_equal) then
                eq:=te_equal
              else
                if (m_mac_procvar in current_settings.modeswitches) and
                   is_procvar_load(p.left) then
                  eq:=te_convert_l2;
            end;
        end;
      end;


    function allowenumop(nt:tnodetype):boolean;
      begin
        result:=(nt in [equaln,unequaln,ltn,lten,gtn,gten]) or
                ((cs_allow_enum_calc in current_settings.localswitches) and
                 (nt in [addn,subn]));
      end;


{****************************************************************************
                           TCallCandidates
****************************************************************************}

    constructor tcallcandidates.create(sym:tprocsym;st:TSymtable;ppn:tnode;ignorevisibility,allowdefaultparas:boolean);
      begin
        if not assigned(sym) then
          internalerror(200411015);
        FOperator:=NOTOKEN;
        FProcsym:=sym;
        FProcsymtable:=st;
        FParanode:=ppn;
        create_candidate_list(ignorevisibility,allowdefaultparas);
      end;


    constructor tcallcandidates.create_operator(op:ttoken;ppn:tnode);
      begin
        FOperator:=op;
        FProcsym:=nil;
        FProcsymtable:=nil;
        FParanode:=ppn;
        create_candidate_list(false,false);
      end;


    destructor tcallcandidates.destroy;
      var
        hpnext,
        hp : pcandidate;
      begin
        hp:=FCandidateProcs;
        while assigned(hp) do
         begin
           hpnext:=hp^.next;
           dispose(hp);
           hp:=hpnext;
         end;
      end;


    procedure tcallcandidates.collect_overloads_in_class(ProcdefOverloadList:TFPObjectList);
      var
        j          : integer;
        pd         : tprocdef;
        srsym      : tsym;
        objdef     : tobjectdef;
        hashedid   : THashedIDString;
        hasoverload : boolean;
      begin
        objdef:=tobjectdef(fprocsym.owner.defowner);
        hashedid.id:=fprocsym.name;
        hasoverload:=false;
        while assigned(objdef) do
         begin
           srsym:=tprocsym(objdef.symtable.FindWithHash(hashedid));
           if assigned(srsym) then
             begin
               if (srsym.typ<>procsym) then
                 internalerror(200111022);
               { add all definitions }
               hasoverload:=false;
               for j:=0 to tprocsym(srsym).ProcdefList.Count-1 do
                 begin
                   pd:=tprocdef(tprocsym(srsym).ProcdefList[j]);
                   if po_overload in pd.procoptions then
                     hasoverload:=true;
                   ProcdefOverloadList.Add(tprocsym(srsym).ProcdefList[j]);
                 end;
               { when there is no explicit overload we stop searching }
               if not hasoverload then
                 break;
             end;
           { next parent }
           objdef:=objdef.childof;
         end;
      end;


    procedure tcallcandidates.collect_overloads_in_units(ProcdefOverloadList:TFPObjectList);
      var
        j          : integer;
        pd         : tprocdef;
        srsymtable : TSymtable;
        srsym      : tsym;
        checkstack : psymtablestackitem;
        hashedid   : THashedIDString;
        hasoverload : boolean;
      begin
        { we search all overloaded operator definitions in the symtablestack. The found
          entries are only added to the procs list and not the procsym, because
          the list can change in every situation }
        if FOperator<>NOTOKEN then
          hashedid.id:=overloaded_names[FOperator]
        else
          hashedid.id:=FProcsym.name;

        checkstack:=symtablestack.stack;
        if assigned(FProcsymtable) then
          begin
            while assigned(checkstack) and
                  (checkstack^.symtable<>FProcsymtable) do
              checkstack:=checkstack^.next;
          end;
        while assigned(checkstack) do
          begin
            srsymtable:=checkstack^.symtable;
            if srsymtable.symtabletype in [localsymtable,staticsymtable,globalsymtable] then
              begin
                srsym:=tprocsym(srsymtable.FindWithHash(hashedid));
                if assigned(srsym) and
                   (srsym.typ=procsym) then
                  begin
                    { Store first procsym found }
                    if not assigned(FProcsym) then
                      FProcsym:=tprocsym(srsym);
                    { add all definitions }
                    hasoverload:=false;
                    for j:=0 to tprocsym(srsym).ProcdefList.Count-1 do
                      begin
                        pd:=tprocdef(tprocsym(srsym).ProcdefList[j]);
                        if po_overload in pd.procoptions then
                          hasoverload:=true;
                        ProcdefOverloadList.Add(tprocsym(srsym).ProcdefList[j]);
                      end;
                    { when there is no explicit overload we stop searching }
                    if not hasoverload then
                      break;
                  end;
              end;
            checkstack:=checkstack^.next;
          end;
      end;


    procedure tcallcandidates.create_candidate_list(ignorevisibility,allowdefaultparas:boolean);
      var
        j     : integer;
        pd    : tprocdef;
        hp    : pcandidate;
        pt    : tcallparanode;
        found : boolean;
        contextobjdef : tobjectdef;
        ProcdefOverloadList : TFPObjectList;
      begin
        FCandidateProcs:=nil;

        { Find all available overloads for this procsym }
        ProcdefOverloadList:=TFPObjectList.Create(false);
        if (FOperator=NOTOKEN) and
           (FProcsym.owner.symtabletype=objectsymtable) then
          collect_overloads_in_class(ProcdefOverloadList)
        else
          collect_overloads_in_units(ProcdefOverloadList);

        { determine length of parameter list.
          for operators also enable the variant-operators if
          a variant parameter is passed }
        FParalength:=0;
        FAllowVariant:=(FOperator=NOTOKEN);
        pt:=tcallparanode(FParaNode);
        while assigned(pt) do
          begin
            if (pt.resultdef.typ=variantdef) then
              FAllowVariant:=true;
            inc(FParalength);
            pt:=tcallparanode(pt.right);
          end;

        { when the class passed is defined in this unit we
          need to use the scope of that class. This is a trick
          that can be used to access protected members in other
          units. At least kylix supports it this way (PFV) }
        if assigned(FProcSymtable) and
           (
            (FProcSymtable.symtabletype=ObjectSymtable) or
            ((FProcSymtable.symtabletype=withsymtable) and
             (FProcSymtable.defowner.typ=objectdef))
           ) and
           (FProcSymtable.defowner.owner.symtabletype in [globalsymtable,staticsymtable]) and
           FProcSymtable.defowner.owner.iscurrentunit then
          contextobjdef:=tobjectdef(FProcSymtable.defowner)
        else
          contextobjdef:=current_objectdef;

        { Process all found overloads }
        for j:=0 to ProcdefOverloadList.Count-1 do
          begin
            pd:=tprocdef(ProcdefOverloadList[j]);

            { only when the # of parameter are supported by the procedure and
              it is visible }
            if (FParalength>=pd.minparacount) and
               (
                (
                 allowdefaultparas and
                 (
                  (FParalength<=pd.maxparacount) or
                  (po_varargs in pd.procoptions)
                 )
                ) or
                (
                 not allowdefaultparas and
                 (FParalength=pd.maxparacount)
                )
               ) and
               (
                ignorevisibility or
                (pd.owner.symtabletype<>objectsymtable) or
                is_visible_for_object(pd,contextobjdef)
               ) then
              begin
                { don't add duplicates, only compare visible parameters for the user }
                found:=false;
                hp:=FCandidateProcs;
                while assigned(hp) do
                  begin
                    if compare_paras(hp^.data.paras,pd.paras,cp_value_equal_const,[cpo_ignorehidden])>=te_equal then
                      begin
                        found:=true;
                        break;
                      end;
                    hp:=hp^.next;
                  end;
                if not found then
                  proc_add(fprocsym,pd);
              end;
          end;

        ProcdefOverloadList.Free;
      end;


    function tcallcandidates.proc_add(ps:tprocsym;pd:tprocdef):pcandidate;
      var
        defaultparacnt : integer;
      begin
        { generate new candidate entry }
        new(result);
        fillchar(result^,sizeof(tcandidate),0);
        result^.data:=pd;
        result^.next:=FCandidateProcs;
        FCandidateProcs:=result;
        inc(FProccnt);
        { Find last parameter, skip all default parameters
          that are not passed. Ignore this skipping for varargs }
        result^.firstparaidx:=pd.paras.count-1;
        if not(po_varargs in pd.procoptions) then
         begin
           { ignore hidden parameters }
           while (result^.firstparaidx>=0) and (vo_is_hidden_para in tparavarsym(pd.paras[result^.firstparaidx]).varoptions) do
             dec(result^.firstparaidx);
           defaultparacnt:=pd.maxparacount-FParalength;
           if defaultparacnt>0 then
             begin
               if defaultparacnt>result^.firstparaidx+1 then
                 internalerror(200401141);
               dec(result^.firstparaidx,defaultparacnt);
             end;
         end;
        { Give a small penalty for overloaded methods not in
          defined the current class/unit }
        if ps.owner<>pd.owner then
          result^.ordinal_distance:=result^.ordinal_distance+1.0;
      end;


    procedure tcallcandidates.list(all:boolean);
      var
        hp : pcandidate;
      begin
        hp:=FCandidateProcs;
        while assigned(hp) do
         begin
           if all or
              (not hp^.invalid) then
             MessagePos1(hp^.data.fileinfo,sym_h_param_list,hp^.data.fullprocname(false));
           hp:=hp^.next;
         end;
      end;


{$ifdef EXTDEBUG}
    procedure tcallcandidates.dump_info(lvl:longint);

        function ParaTreeStr(p:tcallparanode):string;
        begin
          result:='';
          while assigned(p) do
           begin
             if result<>'' then
              result:=','+result;
             result:=p.resultdef.typename+result;
             p:=tcallparanode(p.right);
           end;
        end;

      var
        hp : pcandidate;
        i  : integer;
        currpara : tparavarsym;
      begin
        if not CheckVerbosity(lvl) then
         exit;
        Comment(lvl+V_LineInfo,'Overloaded callnode: '+FProcsym.name+'('+ParaTreeStr(tcallparanode(FParaNode))+')');
        hp:=FCandidateProcs;
        while assigned(hp) do
         begin
           Comment(lvl,'  '+hp^.data.fullprocname(false));
           if (hp^.invalid) then
            Comment(lvl,'   invalid')
           else
            begin
              Comment(lvl,'   ex: '+tostr(hp^.exact_count)+
                          ' eq: '+tostr(hp^.equal_count)+
                          ' l1: '+tostr(hp^.cl1_count)+
                          ' l2: '+tostr(hp^.cl2_count)+
                          ' l3: '+tostr(hp^.cl3_count)+
                          ' l4: '+tostr(hp^.cl4_count)+
                          ' l5: '+tostr(hp^.cl5_count)+
                          ' oper: '+tostr(hp^.coper_count)+
                          ' ord: '+realtostr(hp^.ordinal_distance));
              { Print parameters in left-right order }
              for i:=0 to hp^.data.paras.count-1 do
               begin
                 currpara:=tparavarsym(hp^.data.paras[i]);
                 if not(vo_is_hidden_para in currpara.varoptions) then
                   Comment(lvl,'    - '+currpara.vardef.typename+' : '+EqualTypeName[currpara.eqval]);
               end;
            end;
           hp:=hp^.next;
         end;
      end;
{$endif EXTDEBUG}


    procedure tcallcandidates.get_information;
      var
        hp       : pcandidate;
        currpara : tparavarsym;
        paraidx  : integer;
        currparanr : byte;
        rfh,rth  : double;
        objdef   : tobjectdef;
        def_from,
        def_to   : tdef;
        currpt,
        pt       : tcallparanode;
        eq       : tequaltype;
        convtype : tconverttype;
        pdtemp,
        pdoper   : tprocdef;
        releasecurrpt : boolean;
        cdoptions : tcompare_defs_options;
        n : tnode;

    {$ifopt r+}{$define ena_r}{$r-}{$endif}
    {$ifopt q+}{$define ena_q}{$q-}{$endif}
      const
        inf=1.0/0.0;
    {$ifdef ena_r}{$r+}{$endif}
    {$ifdef ena_q}{$q+}{$endif}

      begin
        cdoptions:=[cdo_check_operator];
        if FAllowVariant then
          include(cdoptions,cdo_allow_variant);
        { process all procs }
        hp:=FCandidateProcs;
        while assigned(hp) do
         begin
           { We compare parameters in reverse order (right to left),
             the firstpara is already pointing to the last parameter
             were we need to start comparing }
           currparanr:=FParalength;
           paraidx:=hp^.firstparaidx;
           while (paraidx>=0) and (vo_is_hidden_para in tparavarsym(hp^.data.paras[paraidx]).varoptions) do
             dec(paraidx);
           pt:=tcallparanode(FParaNode);
           while assigned(pt) and (paraidx>=0) do
            begin
              currpara:=tparavarsym(hp^.data.paras[paraidx]);
              { currpt can be changed from loadn to calln when a procvar
                is passed. This is to prevent that the change is permanent }
              currpt:=pt;
              releasecurrpt:=false;
              { retrieve current parameter definitions to compares }
              eq:=te_incompatible;
              def_from:=currpt.resultdef;
              def_to:=currpara.vardef;
              if not(assigned(def_from)) then
               internalerror(200212091);
              if not(
                     assigned(def_to) or
                     ((po_varargs in hp^.data.procoptions) and
                      (currparanr>hp^.data.minparacount))
                    ) then
               internalerror(200212092);

              { Convert tp procvars when not expecting a procvar }
             if (currpt.left.resultdef.typ=procvardef) and
                not(def_to.typ in [procvardef,formaldef]) and
                 { Only convert to call when there is no overload or the return type
                   is equal to the expected type. }
                 (
                  (count=1) or
                  equal_defs(tprocvardef(currpt.left.resultdef).returndef,def_to)
                 ) then
                begin
                  releasecurrpt:=true;
                  currpt:=tcallparanode(pt.getcopy);
                  if maybe_call_procvar(currpt.left,true) then
                    begin
                      currpt.resultdef:=currpt.left.resultdef;
                      def_from:=currpt.left.resultdef;
                    end;
                end;

             { If we expect a procvar and the left is loadnode that
               returns a procdef we need to find the correct overloaded
               procdef that matches the expected procvar. The loadnode
               temporary returned the first procdef (PFV) }
             if (def_to.typ=procvardef) and
                (currpt.left.nodetype=loadn) and
                (currpt.left.resultdef.typ=procdef) then
               begin
                 pdtemp:=tprocsym(Tloadnode(currpt.left).symtableentry).Find_procdef_byprocvardef(Tprocvardef(def_to));
                 if assigned(pdtemp) then
                   begin
                     tloadnode(currpt.left).setprocdef(pdtemp);
                     currpt.resultdef:=currpt.left.resultdef;
                     def_from:=currpt.left.resultdef;
                   end;
               end;

              { varargs are always equal, but not exact }
              if (po_varargs in hp^.data.procoptions) and
                 (currparanr>hp^.data.minparacount) and
                 not is_array_of_const(def_from) and
                 not is_array_constructor(def_from) then
                eq:=te_equal
              else
              { same definition -> exact }
               if (def_from=def_to) then
                 eq:=te_exact
              else
              { for value and const parameters check if a integer is constant or
                included in other integer -> equal and calc ordinal_distance }
               if not(currpara.varspez in [vs_var,vs_out]) and
                  is_integer(def_from) and
                  is_integer(def_to) and
                  is_in_limit(def_from,def_to) then
                 begin
                   eq:=te_equal;
                   hp^.ordinal_distance:=hp^.ordinal_distance+
                     abs(bestreal(torddef(def_from).low)-bestreal(torddef(def_to).low));
                   rth:=bestreal(torddef(def_to).high);
                   rfh:=bestreal(torddef(def_from).high);
                   hp^.ordinal_distance:=hp^.ordinal_distance+abs(rth-rfh);
                   { Give wrong sign a small penalty, this is need to get a diffrence
                     from word->[longword,longint] }
                   if is_signed(def_from)<>is_signed(def_to) then
                   {$ifopt r+}{$define ena_rq}{$q-}{$r-}{$endif}
                     hp^.ordinal_distance:=nextafter(hp^.ordinal_distance,inf);
                   {$ifdef ena_rq}{$r+}{$q+}{$endif}
                 end
              else
              { for value and const parameters check precision of real, give
                penalty for loosing of precision. var and out parameters must match exactly }
               if not(currpara.varspez in [vs_var,vs_out]) and
                  is_real(def_from) and
                  is_real(def_to) then
                 begin
                   eq:=te_equal;
                   if is_extended(def_to) then
                     rth:=4
                   else
                     if is_double (def_to) then
                       rth:=2
                   else
                     rth:=1;
                   if is_extended(def_from) then
                     rfh:=4
                   else
                     if is_double (def_from) then
                       rfh:=2
                   else
                     rfh:=1;
                   { penalty for shrinking of precision }
                   if rth<rfh then
                     rfh:=(rfh-rth)*16
                   else
                     rfh:=rth-rfh;
                   hp^.ordinal_distance:=hp^.ordinal_distance+rfh;
                 end
              else
              { related object parameters also need to determine the distance between the current
                object and the object we are comparing with. var and out parameters must match exactly }
               if not(currpara.varspez in [vs_var,vs_out]) and
                  (def_from.typ=objectdef) and
                  (def_to.typ=objectdef) and
                  (tobjectdef(def_from).objecttype=tobjectdef(def_to).objecttype) and
                  tobjectdef(def_from).is_related(tobjectdef(def_to)) then
                 begin
                   eq:=te_convert_l1;
                   objdef:=tobjectdef(def_from);
                   while assigned(objdef) do
                     begin
                       if objdef=def_to then
                         break;
                       hp^.ordinal_distance:=hp^.ordinal_distance+1;
                       objdef:=objdef.childof;
                     end;
                 end
               { compare_defs_ext compares sets and array constructors very poorly because
                 it has too little information. So we do explicitly a detailed comparisation,
                 see also bug #11288 (FK)
               }
               else if (def_to.typ=setdef) and is_array_constructor(currpt.left.resultdef) then
                 begin
                   n:=currpt.left.getcopy;
                   arrayconstructor_to_set(n);
                   eq:=compare_defs_ext(n.resultdef,def_to,n.nodetype,convtype,pdoper,cdoptions);
                   n.free;
                 end
              else
              { generic type comparision }
               begin
                 eq:=compare_defs_ext(def_from,def_to,currpt.left.nodetype,convtype,pdoper,cdoptions);

                 { when the types are not equal we need to check
                   some special case for parameter passing }
                 if (eq<te_equal) then
                  begin
                    if currpara.varspez in [vs_var,vs_out] then
                      begin
                        { para requires an equal type so the previous found
                          match was not good enough, reset to incompatible }
                        eq:=te_incompatible;
                        { var_para_allowed will return te_equal and te_convert_l1 to
                          make a difference for best matching }
                        var_para_allowed(eq,currpt.resultdef,currpara.vardef,currpt.left)
                      end
                    else
                      para_allowed(eq,currpt,def_to);
                  end;
               end;

              { when a procvar was changed to a call an exact much is
                downgraded to equal. This way an overload call with the
                procvar is choosen. See tb0471 (PFV) }
              if (pt<>currpt) and (eq=te_exact) then
                eq:=te_equal;

              { increase correct counter }
              case eq of
                te_exact :
                  inc(hp^.exact_count);
                te_equal :
                  inc(hp^.equal_count);
                te_convert_l1 :
                  inc(hp^.cl1_count);
                te_convert_l2 :
                  inc(hp^.cl2_count);
                te_convert_l3 :
                  inc(hp^.cl3_count);
                te_convert_l4 :
                  inc(hp^.cl4_count);
                te_convert_l5 :
                  inc(hp^.cl5_count);
                te_convert_operator :
                  inc(hp^.coper_count);
                te_incompatible :
                  hp^.invalid:=true;
                else
                  internalerror(200212072);
              end;

              { stop checking when an incompatible parameter is found }
              if hp^.invalid then
               begin
                 { store the current parameter info for
                   a nice error message when no procedure is found }
                 hp^.wrongparaidx:=paraidx;
                 hp^.wrongparanr:=currparanr;
                 break;
               end;

{$ifdef EXTDEBUG}
              { store equal in node tree for dump }
              currpara.eqval:=eq;
{$endif EXTDEBUG}

              { maybe release temp currpt }
              if releasecurrpt then
                currpt.free;

              { next parameter in the call tree }
              pt:=tcallparanode(pt.right);

              { next parameter for definition, only goto next para
                if we're out of the varargs }
              if not(po_varargs in hp^.data.procoptions) or
                 (currparanr<=hp^.data.maxparacount) then
               begin
                 { Ignore vs_hidden parameters }
                 repeat
                   dec(paraidx);
                 until (paraidx<0) or not(vo_is_hidden_para in tparavarsym(hp^.data.paras[paraidx]).varoptions);
               end;
              dec(currparanr);
            end;
           if not(hp^.invalid) and
              (assigned(pt) or (paraidx>=0) or (currparanr<>0)) then
             internalerror(200212141);
           { next candidate }
           hp:=hp^.next;
         end;
      end;


    function get_variantequaltype(def: tdef): tvariantequaltype;
      const
        variantorddef_cl: array[tordtype] of tvariantequaltype =
          (tve_incompatible,tve_byte,tve_word,tve_cardinal,tve_chari64,
           tve_shortint,tve_smallint,tve_longint,tve_chari64,
           tve_boolformal,tve_boolformal,tve_boolformal,tve_boolformal,tve_boolformal,
           tve_chari64,tve_chari64,tve_dblcurrency);
{ TODO: fixme for 128 bit floats }
        variantfloatdef_cl: array[tfloattype] of tvariantequaltype =
          (tve_single,tve_dblcurrency,tve_extended,
           tve_dblcurrency,tve_dblcurrency,tve_extended);
        variantstringdef_cl: array[tstringtype] of tvariantequaltype =
          (tve_sstring,tve_astring,tve_astring,tve_wstring,tve_ustring);
      begin
        case def.typ of
          orddef:
            begin
              result:=variantorddef_cl[torddef(def).ordtype];
            end;
          floatdef:
            begin
              result:=variantfloatdef_cl[tfloatdef(def).floattype];
            end;
          stringdef:
            begin
              result:=variantstringdef_cl[tstringdef(def).stringtype];
            end;
          formaldef:
            begin
              result:=tve_boolformal;
            end;
          else
            begin
              result:=tve_incompatible;
            end;
        end
      end;


    function is_better_candidate(currpd,bestpd:pcandidate):integer;
      var
        res : integer;
      begin
        {
          Return values:
            > 0 when currpd is better than bestpd
            < 0 when bestpd is better than currpd
            = 0 when both are equal

          To choose the best candidate we use the following order:
          - Incompatible flag
          - (Smaller) Number of convert operator parameters.
          - (Smaller) Number of convertlevel 2 parameters.
          - (Smaller) Number of convertlevel 1 parameters.
          - (Bigger) Number of exact parameters.
          - (Smaller) Number of equal parameters.
          - (Smaller) Total of ordinal distance. For example, the distance of a word
            to a byte is 65535-255=65280.
        }
        if bestpd^.invalid then
         begin
           if currpd^.invalid then
            res:=0
           else
            res:=1;
         end
        else
         if currpd^.invalid then
          res:=-1
        else
         begin
           { less operator parameters? }
           res:=(bestpd^.coper_count-currpd^.coper_count);
           if (res=0) then
            begin
             { less cl5 parameters? }
             res:=(bestpd^.cl5_count-currpd^.cl5_count);
             if (res=0) then
              begin
               { less cl4 parameters? }
               res:=(bestpd^.cl4_count-currpd^.cl4_count);
               if (res=0) then
                begin
                 { less cl3 parameters? }
                 res:=(bestpd^.cl3_count-currpd^.cl3_count);
                 if (res=0) then
                  begin
                    { less cl2 parameters? }
                    res:=(bestpd^.cl2_count-currpd^.cl2_count);
                    if (res=0) then
                     begin
                       { less cl1 parameters? }
                       res:=(bestpd^.cl1_count-currpd^.cl1_count);
                       if (res=0) then
                        begin
                          { more exact parameters? }
                          res:=(currpd^.exact_count-bestpd^.exact_count);
                          if (res=0) then
                           begin
                             { less equal parameters? }
                             res:=(bestpd^.equal_count-currpd^.equal_count);
                             if (res=0) then
                              begin
                                { smaller ordinal distance? }
                                if (currpd^.ordinal_distance<bestpd^.ordinal_distance) then
                                 res:=1
                                else
                                 if (currpd^.ordinal_distance>bestpd^.ordinal_distance) then
                                  res:=-1
                                else
                                 res:=0;
                              end;
                           end;
                        end;
                     end;
                  end;
                end;
              end;
            end;
         end;
        is_better_candidate:=res;
      end;


{ Delphi precedence rules extracted from test programs. Only valid if passing
  a variant parameter to overloaded procedures expecting exactly one parameter.

  single > (char, currency, int64, shortstring, ansistring, widestring, extended, double)
  double/currency > (char, int64, shortstring, ansistring, widestring, extended)
  extended > (char, int64, shortstring, ansistring, widestring)
  longint/cardinal > (int64, shortstring, ansistring, widestring, extended, double, single, char, currency)
  smallint > (longint, int64, shortstring, ansistring, widestring, extended, double single, char, currency);
  word > (longint, cardinal, int64, shortstring, ansistring, widestring, extended, double single, char, currency);
  shortint > (longint, smallint, int64, shortstring, ansistring, widestring, extended, double, single, char, currency)
  byte > (longint, cardinal, word, smallint, int64, shortstring, ansistring, widestring, extended, double, single, char, currency);
  boolean/formal > (char, int64, shortstring, ansistring, widestring)
  shortstring > (char, int64, ansistring, widestring)
  ansistring > (char, int64, widestring)
  widestring > (char, int64)

  Relations not mentioned mean that they conflict: no decision possible }

    function is_better_candidate_single_variant(currpd,bestpd:pcandidate):integer;

      function calculate_relation(const currvcl, bestvcl, testvcl:
          tvariantequaltype; const conflictvcls: tvariantequaltypes):integer;
        begin
          { if (bestvcl=conflictvcl) or
               (currvcl=conflictvcl) then
              result:=0
            else if (bestvcl=testvcl) then
              result:=-1
            else result:=1 }
          result:=1-2*ord(bestvcl=testvcl)+
                  ord(currvcl in conflictvcls)-ord(bestvcl in conflictvcls);
        end;


        function getfirstrealparaidx(pd: pcandidate): integer;
          begin
            { can be different for currpd and bestpd in case of overloaded }
            { functions, e.g. lowercase():char and lowercase():shortstring }
            { (depending on the calling convention and parameter order)    }
            result:=pd^.firstparaidx;
            while (result>=0) and (vo_is_hidden_para in tparavarsym(pd^.data.paras[result]).varoptions) do
              dec(result);
            if (vo_is_hidden_para in tparavarsym(pd^.data.paras[result]).varoptions) then
              internalerror(2006122803);
          end;

      var
        currpara, bestpara: tparavarsym;
        currvcl, bestvcl: tvariantequaltype;
      begin
        {
          Return values:
            > 0 when currpd is better than bestpd
            < 0 when bestpd is better than currpd
            = 0 when both are equal
        }
        currpara:=tparavarsym(currpd^.data.paras[getfirstrealparaidx(currpd)]);
        bestpara:=tparavarsym(bestpd^.data.paras[getfirstrealparaidx(bestpd)]);

        { if one of the parameters is a regular variant, fall back to the }
        { default algorithm                                               }
        if (currpara.vardef.typ = variantdef) or
           (bestpara.vardef.typ = variantdef) then
          begin
            result:=is_better_candidate(currpd,bestpd);
            exit;
          end;

        currvcl:=get_variantequaltype(currpara.vardef);
        bestvcl:=get_variantequaltype(bestpara.vardef);

        { sanity check }
        result:=-5;

        { if both are the same, there is a conflict }
        if (currvcl=bestvcl) then
          result:=0
        { if one of the two cannot be used as variant, the other is better }
        else if (bestvcl=tve_incompatible) then
          result:=1
        else if (currvcl=tve_incompatible) then
          result:=-1
        { boolean and formal are better than chari64str, but conflict with }
        { everything else                                                  }
        else if (currvcl=tve_boolformal) or
                (bestvcl=tve_boolformal) then
          if (currvcl=tve_boolformal) then
            result:=ord(bestvcl in [tve_chari64,tve_sstring,tve_astring,tve_wstring,tve_ustring])
          else
            result:=-ord(currvcl in [tve_chari64,tve_sstring,tve_astring,tve_wstring,tve_ustring])
        { byte is better than everything else (we assume both aren't byte, }
        { since there's only one parameter and that one can't be the same) }
        else if (currvcl=tve_byte) or
                (bestvcl=tve_byte) then
          result:=calculate_relation(currvcl,bestvcl,tve_byte,[tve_shortint])
        { shortint conflicts with word and cardinal, but is better than    }
        { everything else but byte (which has already been handled)        }
        else if (currvcl=tve_shortint) or
                (bestvcl=tve_shortint) then
          result:=calculate_relation(currvcl,bestvcl,tve_shortint,[tve_word, tve_cardinal])
        { word conflicts with smallint, but is better than everything else }
        { but shortint and byte (which has already been handled)           }
        else if (currvcl=tve_word) or
                (bestvcl=tve_word) then
          result:=calculate_relation(currvcl,bestvcl,tve_word,[tve_smallint])
        { smallint conflicts with cardinal, but is better than everything  }
        { which has not yet been tested                                    }
        else if (currvcl=tve_smallint) or
                (bestvcl=tve_smallint) then
          result:=calculate_relation(currvcl,bestvcl,tve_smallint,[tve_cardinal])
        { cardinal conflicts with each longint and is better than everything }
        { which has not yet been tested                                      }
        else if (currvcl=tve_cardinal) or
                (bestvcl=tve_cardinal) then
          result:=calculate_relation(currvcl,bestvcl,tve_cardinal,[tve_longint])
        { longint is better than everything which has not yet been tested }
        else if (currvcl=tve_longint) or
                (bestvcl=tve_longint) then
          { if bestvcl=tve_longint then
              result:=-1
            else
              result:=1 }
          result:=1-2*ord(bestvcl=tve_longint)
        { single is better than everything left }
        else if (currvcl=tve_single) or
                (bestvcl=tve_single) then
          result:=1-2*ord(bestvcl=tve_single)
        { double/comp/currency are better than everything left, and conflict }
        { with each other (but that's already tested)                        }
        else if (currvcl=tve_dblcurrency) or
                (bestvcl=tve_dblcurrency) then
          result:=1-2*ord(bestvcl=tve_dblcurrency)
        { extended is better than everything left }
        else if (currvcl=tve_extended) or
                (bestvcl=tve_extended) then
          result:=1-2*ord(bestvcl=tve_extended)
        { shortstring is better than everything left }
        else if (currvcl=tve_sstring) or
                (bestvcl=tve_sstring) then
          result:=1-2*ord(bestvcl=tve_sstring)
        { ansistring is better than everything left }
        else if (currvcl=tve_astring) or
                (bestvcl=tve_astring) then
          result:=1-2*ord(bestvcl=tve_astring)
        { widestring is better than everything left }
        else if (currvcl=tve_wstring) or
                (bestvcl=tve_wstring) then
          result:=1-2*ord(bestvcl=tve_wstring)
        { unicodestring is better than everything left }
        else if (currvcl=tve_ustring) or
                (bestvcl=tve_ustring) then
          result:=1-2*ord(bestvcl=tve_ustring);

        { all possibilities should have been checked now }
        if (result=-5) then
          internalerror(2006122805);
      end;


    function tcallcandidates.choose_best(var bestpd:tabstractprocdef; singlevariant: boolean):integer;
      var
        besthpstart,
        hp            : pcandidate;
        cntpd,
        res           : integer;
      begin
        {
          Returns the number of candidates left and the
          first candidate is returned in pdbest
        }
        { Setup the first procdef as best, only count it as a result
          when it is valid }
        bestpd:=FCandidateProcs^.data;
        if FCandidateProcs^.invalid then
         cntpd:=0
        else
         cntpd:=1;
        if assigned(FCandidateProcs^.next) then
         begin
           besthpstart:=FCandidateProcs;
           hp:=FCandidateProcs^.next;
           while assigned(hp) do
            begin
              if not singlevariant then
                res:=is_better_candidate(hp,besthpstart)
              else
                res:=is_better_candidate_single_variant(hp,besthpstart);
              if (res>0) then
               begin
                 { hp is better, flag all procs to be incompatible }
                 while (besthpstart<>hp) do
                  begin
                    besthpstart^.invalid:=true;
                    besthpstart:=besthpstart^.next;
                  end;
                 { besthpstart is already set to hp }
                 bestpd:=besthpstart^.data;
                 cntpd:=1;
               end
              else
               if (res<0) then
                begin
                  { besthpstart is better, flag current hp to be incompatible }
                  hp^.invalid:=true;
                end
              else
               begin
                 { res=0, both are valid }
                 if not hp^.invalid then
                   inc(cntpd);
               end;
              hp:=hp^.next;
            end;
         end;

        result:=cntpd;
      end;


    procedure tcallcandidates.find_wrong_para;
      var
        currparanr : smallint;
        hp : pcandidate;
        pt : tcallparanode;
        wrongpara : tparavarsym;
      begin
        { Only process the first overloaded procdef }
        hp:=FCandidateProcs;
        { Find callparanode corresponding to the argument }
        pt:=tcallparanode(FParanode);
        currparanr:=FParalength;
        while assigned(pt) and
              (currparanr>hp^.wrongparanr) do
         begin
           pt:=tcallparanode(pt.right);
           dec(currparanr);
         end;
        if (currparanr<>hp^.wrongparanr) or
           not assigned(pt) then
          internalerror(200212094);
        { Show error message, when it was a var or out parameter
          guess that it is a missing typeconv }
        wrongpara:=tparavarsym(hp^.data.paras[hp^.wrongparaidx]);
        if wrongpara.varspez in [vs_var,vs_out] then
          begin
            { Maybe passing the correct type but passing a const to var parameter }
            if (compare_defs(pt.resultdef,wrongpara.vardef,pt.nodetype)<>te_incompatible) and
               not valid_for_var(pt.left,true) then
              CGMessagePos(pt.left.fileinfo,type_e_variable_id_expected)
            else
              CGMessagePos3(pt.left.fileinfo,parser_e_call_by_ref_without_typeconv,tostr(hp^.wrongparanr),
                FullTypeName(pt.left.resultdef,wrongpara.vardef),
                FullTypeName(wrongpara.vardef,pt.left.resultdef))
          end
        else
          CGMessagePos3(pt.left.fileinfo,type_e_wrong_parameter_type,tostr(hp^.wrongparanr),
            FullTypeName(pt.left.resultdef,wrongpara.vardef),
            FullTypeName(wrongpara.vardef,pt.left.resultdef));
      end;


    procedure check_hints(const srsym: tsym; const symoptions: tsymoptions);
      begin
        if not assigned(srsym) then
          internalerror(200602051);
        if sp_hint_deprecated in symoptions then
          Message1(sym_w_deprecated_symbol,srsym.realname);
        if sp_hint_experimental in symoptions then
          Message1(sym_w_experimental_symbol,srsym.realname);
        if sp_hint_platform in symoptions then
          Message1(sym_w_non_portable_symbol,srsym.realname);
        if sp_hint_unimplemented in symoptions then
          Message1(sym_w_non_implemented_symbol,srsym.realname);
      end;


    procedure check_ranges(const location: tfileposinfo; source: tnode; destdef: tdef);
      begin
        if not(cs_check_ordinal_size in current_settings.localswitches) then
          exit;
        { check if the assignment may cause a range check error }
        { if its not explicit, and only if the values are       }
        { ordinals, enumdef and floatdef                        }
        if assigned(destdef) and
          (destdef.typ in [enumdef,orddef,floatdef]) and
          not is_boolean(destdef) and
          assigned(source.resultdef) and
          (source.resultdef.typ in [enumdef,orddef,floatdef]) and
          not is_boolean(source.resultdef) and
          not is_constrealnode(source) then
         begin
           if (destdef.size < source.resultdef.size) then
             begin
               if (cs_check_range in current_settings.localswitches) then
                 MessagePos(location,type_w_smaller_possible_range_check)
               else
                 MessagePos(location,type_h_smaller_possible_range_check);
             end;
         end;
      end;


end.