freepascal.compiler/compiler/objcutil.pas

{
    Copyright (c) 2009 by Jonas Maebe

    This unit implements some Objective-C helper routines at the node tree
    level.

    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.

 ****************************************************************************
}

{$i fpcdefs.inc}

unit objcutil;

interface

    uses
      node,
      symtype,symdef;

    { Check whether a string contains a syntactically valid selector name.  }
    function objcvalidselectorname(value_str: pchar; len: longint): boolean;

    { Generate a node loading the superclass structure necessary to call
      an inherited Objective-C method.  }
    function objcsuperclassnode(def: tdef): tnode;

    { The internals of Objective-C's @encode() functionality: encode a
      type into the internal format used by the run time. Returns false
      if a type is not representable by the Objective-C run time, and in
      that case also the failing definition.  }
    function objctryencodetype(def: tdef; out encodedtype: ansistring; out founderror: tdef): boolean;

    { Encode a method's parameters and result type into the format used by the
      run time (for generating protocol and class rtti).  }
    function objcencodemethod(pd: tprocdef): ansistring;

    { Check whether a type can be used in an Objective-C method
      signature or field declaration.  }
    function objcchecktype(def: tdef; out founderror: tdef): boolean;

    { Exports all assembler symbols related to the obj-c class }
    procedure exportobjcclass(def: tobjectdef);

implementation

    uses
      globtype,
      cutils,cclasses,
      pass_1,
      verbose,systems,
      symtable,symconst,symsym,
      defutil,paramgr,
      nbas,nmem,ncal,nld,ncon,ncnv,
      export;


{******************************************************************
                       validselectorname
*******************************************************************}

function objcvalidselectorname(value_str: pchar; len: longint): boolean;
  var
    i         : longint;
    gotcolon  : boolean;
begin
  result:=false;
  { empty name is not allowed }
  if (len=0) then
    exit;

  gotcolon:=false;

  { if the first character is a colon, all of them must be colons }
  if (value_str[0] = ':') then
    begin
      for i:=1 to len-1 do
        if (value_str[i]<>':') then
          exit;
    end
  else
    begin
      { no special characters other than ':'
      }
      for i:=0 to len-1 do
        if (value_str[i] = ':') then
          gotcolon:=true
        else if not(value_str[i] in ['_','A'..'Z','a'..'z','0'..'9',':']) then
          exit;

      { if there is at least one colon, the final character must
        also be a colon (in case it's only one character that is
        a colon, this was already checked before the above loop)
      }
      if gotcolon and
         (value_str[len-1] <> ':') then
        exit;
    end;

  result:=true;
end;

{******************************************************************
                       objcsuperclassnode
*******************************************************************}

    function objcloadbasefield(n: tnode; const fieldname: string): tnode;
      var
        vs         : tsym;
      begin
        result:=ctypeconvnode.create_internal(cderefnode.create(ctypeconvnode.create_internal(n,voidpointertype)),objc_objecttype);
        vs:=tsym(tabstractrecorddef(objc_objecttype).symtable.Find(fieldname));
        if not assigned(vs) or
           (vs.typ<>fieldvarsym) then
          internalerror(200911301);
        result:=csubscriptnode.create(vs,result);
      end;


    function objcsuperclassnode(def: tdef): tnode;
      var
        para       : tcallparanode;
      begin
        { only valid for Objective-C classes and classrefs }
        if not is_objcclass(def) and
           not is_objcclassref(def) then
          internalerror(2009090901);
        { Can be done a lot more efficiently with direct symbol accesses, but
          requires extra node types. Maybe later. }
        if is_objcclassref(def) then
          begin
            if (oo_is_classhelper in tobjectdef(tclassrefdef(def).pointeddef).objectoptions) then
              begin
                { in case we are in a category method, we need the metaclass of the
                  superclass class extended by this category (= metaclass of superclass of superclass) }
                result:=cloadvmtaddrnode.create(ctypenode.create(tobjectdef(tclassrefdef(def).pointeddef).childof.childof));
                result:=objcloadbasefield(result,'ISA');
                typecheckpass(result);
                { we're done }
                exit;
              end
            else
              begin
                { otherwise we need the superclass of the metaclass }
                para:=ccallparanode.create(cstringconstnode.createstr(tobjectdef(tclassrefdef(def).pointeddef).objextname^),nil);
                result:=ccallnode.createinternfromunit('OBJC','OBJC_GETMETACLASS',para);
              end
          end
        else
          begin
            if not(oo_is_classhelper in tobjectdef(def).objectoptions) then
              result:=cloadvmtaddrnode.create(ctypenode.create(def))
            else
              result:=cloadvmtaddrnode.create(ctypenode.create(tobjectdef(def).childof))
          end;

{$if defined(onlymacosx10_6) or defined(arm) }
        { For the non-fragile ABI, the superclass send2 method itself loads the
          superclass. For the fragile ABI, we have to do this ourselves.

          NOTE: those send2 methods are only available on Mac OS X 10.6 and later!
            (but also on all iPhone SDK revisions we support) }
        if not(target_info.system in system_objc_nfabi) then
{$endif onlymacosx10_6 or arm}
          result:=objcloadbasefield(result,'SUPERCLASS');
        typecheckpass(result);
      end;


{******************************************************************
                          Type encoding
*******************************************************************}

    type
      trecordinfostate = (ris_initial, ris_afterpointer, ris_dontprint);

    function objcparasize(vs: tparavarsym): ptrint;
      begin
        result:=vs.paraloc[callerside].intsize;
        { In Objective-C, all ordinal types are widened to at least the
          size of the C "int" type. Assume __LP64__/4 byte ints for now. }
        if is_ordinal(vs.vardef) and
           (result<4) then
          result:=4;
      end;


    function addencodedtype(def: tdef; recordinfostate: trecordinfostate; bpacked: boolean; var encodedstr: ansistring; out founderror: tdef): boolean; forward;

    function encoderecst(const recname: ansistring; recst: tabstractrecordsymtable; var encodedstr: ansistring; out founderror: tdef): boolean;
      var
        variantstarts: tfplist;
        i, varindex: longint;
        field,
        firstfield: tfieldvarsym;
        firstfieldvariant,
        bpacked: boolean;
      begin
        result:=false;
        bpacked:=recst.fieldalignment=bit_alignment;
        { Is the first field already the start of a variant?  }
        firstfield:=nil;
        firstfieldvariant:=false;
        for i:=0 to recst.symlist.count-1 do
          begin
            if (tsym(recst.symlist[i]).typ<>fieldvarsym) then
              continue;
            field:=tfieldvarsym(recst.symlist[i]);
            if not assigned(firstfield) then
              firstfield:=field
            else if (vo_is_first_field in field.varoptions) then
              begin
                if (field.fieldoffset=firstfield.fieldoffset) then
                  firstfieldvariant:=true;
              end;
          end;
        variantstarts:=tfplist.create;
        encodedstr:=encodedstr+'{'+recname+'=';
        for i:=0 to recst.symlist.count-1 do
          begin
            if (tsym(recst.symlist[i]).typ<>fieldvarsym) then
              continue;

            field:=tfieldvarsym(recst.symlist[i]);
            { start of a variant part? }
            if ((field=firstfield) and
                firstfieldvariant) or
               ((field<>firstfield) and
                (vo_is_first_field in field.varoptions)) then
              begin
                varindex:=variantstarts.count-1;
                if (varindex=-1) or
                   (tfieldvarsym(variantstarts[varindex]).fieldoffset<field.fieldoffset) then
                  begin
                    { new, more deeply nested variant }
                    encodedstr:=encodedstr+'(?={?=';
                    variantstarts.add(field);
                  end
                else
                  begin
                    { close existing nested variants if any }
                    while (varindex>=0) and
                          (tfieldvarsym(variantstarts[varindex]).fieldoffset>field.fieldoffset) do
                      begin
                        { close more deeply nested variants }
                        encodedstr:=encodedstr+'})';
                        dec(varindex);
                      end;
                    if (varindex<0) then
                      internalerror(2009081805);
                    if (tfieldvarsym(variantstarts[varindex]).fieldoffset<>field.fieldoffset) then
                      internalerror(2009081804);

                    { variant at the same level as a previous one }
                    variantstarts.count:=varindex+1;
                    { No need to add this field, it has the same offset as the
                      previous one at this position.  }
                    if tfieldvarsym(variantstarts[varindex]).fieldoffset<>field.fieldoffset then
                      internalerror(2009081601);
                    { close previous variant sub-part and start new one }
                    encodedstr:=encodedstr+'}{?=';
                  end
              end;
            if not addencodedtype(field.vardef,ris_afterpointer,bpacked,encodedstr,founderror) then
              exit;
          end;
        for i:=0 to variantstarts.count-1 do
          encodedstr:=encodedstr+'})';
        variantstarts.free;
        encodedstr:=encodedstr+'}';
        result:=true
      end;


    function addencodedtype(def: tdef; recordinfostate: trecordinfostate; bpacked: boolean; var encodedstr: ansistring; out founderror: tdef): boolean;
      var
        recname: ansistring;
        recdef: trecorddef;
        objdef: tobjectdef;
        len: aint;
        c: char;
        newstate: trecordinfostate;
        addrpara: boolean;
      begin
        result:=true;
        case def.typ of
          stringdef :
            begin
              case tstringdef(def).stringtype of
                st_shortstring:
                  { include length byte }
                  encodedstr:=encodedstr+'['+tostr(tstringdef(def).len+1)+'C]';
                else
                  { While we could handle refcounted Pascal strings correctly
                    when such methods are called from Pascal code, things would
                    completely break down if they were called from Objective-C
                    code/reflection since the necessary refcount helper calls
                    would be missing on the caller side (unless we'd
                    automatically generate wrappers).  }
                  result:=false;
              end;
            end;
          enumdef,
          orddef :
            begin
              if bpacked and
                 not is_void(def) then
                encodedstr:=encodedstr+'b'+tostr(def.packedbitsize)
              else
                begin
                  if is_void(def) then
                    c:='v'
                  { in gcc, sizeof(_Bool) = sizeof(char) }
                  else if is_boolean(def) and
                          (def.size=1) then
                    c:='B'
                  else
                    begin
                      case def.size of
                        1:
                          c:='c';
                        2:
                          c:='s';
                        4:
                          c:='i';
                        8:
                          c:='q';
                        else
                          internalerror(2009081502);
                      end;
                      if not is_signed(def) then
                        c:=upcase(c);
                    end;
                  encodedstr:=encodedstr+c;
                end;
            end;
          pointerdef :
            begin
              if is_pchar(def) then
                encodedstr:=encodedstr+'*'
              else if (def=objc_idtype) then
                encodedstr:=encodedstr+'@'
              else if (def=objc_seltype) then
                encodedstr:=encodedstr+':'
              else if (def=objc_metaclasstype) then
                encodedstr:=encodedstr+'#'
              else
                begin
                  encodedstr:=encodedstr+'^';
                  newstate:=recordinfostate;
                  if (recordinfostate<ris_dontprint) then
                    newstate:=succ(newstate);
                  if not addencodedtype(tpointerdef(def).pointeddef,newstate,false,encodedstr,founderror) then
                    begin
                      result:=false;
                      { report the exact (nested) error defintion }
                      exit;
                    end;
                end;
            end;
          floatdef :
            begin
              case tfloatdef(def).floattype of
                s32real:
                  c:='f';
                s64real:
                  c:='d';
                else
                  begin
                    c:='!';
                    result:=false;
                  end;
              end;
              encodedstr:=encodedstr+c;
            end;
          filedef :
            result:=false;
          recorddef :
            begin
              if assigned(def.typesym) then
                recname:=def.typename
              else
                recname:='?';

              if (recordinfostate<>ris_dontprint) then
                begin
                  if not encoderecst(recname,tabstractrecordsymtable(trecorddef(def).symtable),encodedstr,founderror) then
                    begin
                      result:=false;
                      { report the exact (nested) error defintion }
                      exit;
                    end
                end
              else
                encodedstr:=encodedstr+'{'+recname+'}'
            end;
          variantdef :
            begin
              recdef:=trecorddef(search_system_type('TVARDATA').typedef);
              if (recordinfostate<>ris_dontprint) then
                begin
                  if not encoderecst(recdef.typename,tabstractrecordsymtable(recdef.symtable),encodedstr,founderror) then
                    begin
                      result:=false;
                      { report the exact (nested) error defintion }
                      exit;
                    end
                end
              else
                encodedstr:=encodedstr+'{'+recdef.typename+'}';
            end;
          classrefdef :
            begin
              encodedstr:=encodedstr+'^';
              newstate:=recordinfostate;
              if (recordinfostate<>ris_dontprint) then
                newstate:=succ(newstate);
              if is_objcclassref(def) then
                begin
                  objdef:=tobjectdef(tclassrefdef(def).pointeddef);
                  if (newstate<>ris_dontprint) then
                    { anonymous (objc)class definitions do not exist }
                    begin
                      if not encoderecst(objdef.objextname^,tabstractrecordsymtable(objdef.symtable),encodedstr,founderror) then
                        { The fields of an Objective-C class should always be
                          encodeable.  }
                        internalerror(2009081702);
                    end
                  else
                    encodedstr:=encodedstr+'{'+objdef.objextname^+'}'
                end
              { Object Pascal classrefdefs point to a vmt, not really useful
                to completely write those here.  I'm not even sure what the
                Objective-C run time uses this information for, since in C you
                can have forward struct definitions so not all structs passed
                to functions can be written out here either -> treat
                classrefdefs the same as such forward-defined structs.  }
              else
                begin
                  if assigned(def.typesym) then
                    recname:=def.typename
                  else
                    recname:='?';
                  encodedstr:=encodedstr+'{'+recname;
                  if (newstate<>ris_dontprint) then
                    encodedstr:=encodedstr+'=';
                  encodedstr:=encodedstr+'}'
                end;
            end;
          setdef :
            begin
              addrpara:=paramanager.push_addr_param(vs_value,def,pocall_cdecl);
              if not addrpara then
                { encode as an record, they are always passed by value in C.  }
                encodedstr:=encodedstr+'{?=';
              { Encode the set itself as an array. Without an encompassing
                record, these are always passed by reference in C.  }
              encodedstr:=encodedstr+'['+tostr(def.size)+'C]';
              if not addrpara then
                encodedstr:=encodedstr+'}';
            end;
          formaldef :
            begin
              encodedstr:=encodedstr+'^v';
            end;
          arraydef :
            begin
              if is_array_of_const(def) then
                { do nothing, varargs are ignored in signatures }
              else if is_special_array(def) then
                result:=false
              else
                begin
                  len:=tarraydef(def).highrange-tarraydef(def).lowrange+1;
                  if is_packed_array(def) then
                    begin
                      { convert from bits to bytes for bitpacked arrays }
                      len:=(len+7) div 8;
                      { and encode as plain array of bytes }
                      encodedstr:=encodedstr+'['+tostr(len)+'C]';
                    end
                  else
                    begin
                      encodedstr:=encodedstr+'['+tostr(len);
                      { Embedded structured types in the array are printed
                        in full regardless of the current recordinfostate.  }
                      if not addencodedtype(tarraydef(def).elementdef,ris_initial,false,encodedstr,founderror) then
                        begin
                          result:=false;
                          { report the exact (nested) error defintion }
                          exit;
                        end;
                      encodedstr:=encodedstr+']';
                    end;
                end;
            end;
          procvardef :
            encodedstr:=encodedstr+'^?';
          objectdef :
            case tobjectdef(def).objecttype of
              odt_class,
              odt_object,
              odt_cppclass:
                begin
                  newstate:=recordinfostate;
                  { implicit pointer for classes }
                  if (tobjectdef(def).objecttype=odt_class) then
                    begin
                      encodedstr:=encodedstr+'^';
                      if (recordinfostate<ris_dontprint) then
                        newstate:=succ(newstate);
                    end;
                  if newstate<>ris_dontprint then
                    begin
                      if not encoderecst(def.typename,tabstractrecordsymtable(tobjectdef(def).symtable),encodedstr,founderror) then
                        begin
                          result:=false;
                          { report the exact (nested) error defintion }
                          exit;
                        end
                    end
                  else
                    encodedstr:=encodedstr+'{'+def.typename+'}'
                end;
              odt_interfacecom,
              odt_interfacecom_property,
              odt_interfacecom_function,
              odt_dispinterface:
                result:=false;
              odt_interfacecorba:
                encodedstr:=encodedstr+'^{'+def.typename+'=}';
              { In Objective-C, the actual types of class instances are
                NSObject* etc, and those are encoded as "@". In FPC, to keep
                the similarity with Delphi-style Object Pascal, the type is
                NSObject and the pointer is implicit. Objective-C's "NSObject"
                has "class of NSObject" as equivalent here.  }
              odt_objcclass,
              odt_objcprotocol:
                encodedstr:=encodedstr+'@';
              else
                internalerror(2009081509);
            end;
          undefineddef,
          errordef :
            result:=false;
          procdef :
            { must be done via objcencodemethod() }
            internalerror(2009081511);
        else
          internalerror(2009150812);
        end;
        if not result then
          founderror:=def;
      end;


    function objctryencodetype(def: tdef; out encodedtype: ansistring; out founderror: tdef): boolean;
      begin
        result:=addencodedtype(def,ris_initial,false,encodedtype,founderror);
      end;


    function objcencodemethod(pd: tprocdef): ansistring;
      var
        parasize,
        totalsize: aint;
        vs: tparavarsym;
        i: longint;
        temp: ansistring;
        founderror: tdef;
      begin
        result:='';
        totalsize:=0;
        if not pd.has_paraloc_info then
          begin
            pd.requiredargarea:=paramanager.create_paraloc_info(pd,callerside);
            pd.has_paraloc_info:=true;
          end;
{$if defined(powerpc) and defined(dummy)}
        { Disabled, because neither Clang nor gcc does this, and the ObjC
          runtime contains an explicit fix to detect this error.  }

        { On ppc, the callee is responsible for removing the hidden function
          result parameter from the stack, so it has to know. On i386, it's
          the caller that does this.  }
        if (pd.returndef<>voidtype) and
            paramgr.ret_in_param(pd.returndef,pocall_cdecl) then
          inc(totalsize,sizeof(pint));
{$endif}
        for i:=0 to pd.paras.count-1 do
          begin
            vs:=tparavarsym(pd.paras[i]);
            if (vo_is_funcret in vs.varoptions) then
              continue;
            { addencodedtype always assumes a value parameter, so add
              a pointer indirection for var/out parameters.  }
            if not paramanager.push_addr_param(vs_value,vs.vardef,pocall_cdecl) and
               (vs.varspez in [vs_var,vs_out]) then
              result:=result+'^';
            { Add the parameter type.  }
            if not addencodedtype(vs.vardef,ris_initial,false,result,founderror) then
              { should be checked earlier on }
              internalerror(2009081701);
            { And the total size of the parameters coming before this one
              (i.e., the "offset" of this parameter).  }
            result:=result+tostr(totalsize);
            { Update the total parameter size }
            parasize:=objcparasize(vs);
            inc(totalsize,parasize);
          end;
        { Prepend the total parameter size.  }
        result:=tostr(totalsize)+result;
        { And the type of the function result (void in case of a procedure).  }
        temp:='';
        if not addencodedtype(pd.returndef,ris_initial,false,temp,founderror) then
          internalerror(2009081801);
        result:=temp+result;
      end;


{******************************************************************
                    ObjC type validity checking
*******************************************************************}

    function objcdochecktype(def: tdef; recordinfostate: trecordinfostate; out founderror: tdef): boolean; forward;

    function checkrecsttype(recst: tabstractrecordsymtable; recordinfostate: trecordinfostate; out founderror: tdef): boolean;
      var
        i: longint;
        field: tfieldvarsym;
        newstate: trecordinfostate;
      begin
        result:=false;
        newstate:=recordinfostate;
        { Although we never have to print the type info for nested
          records, check them anyway in case we're not after a pointer
          since if such records contain refcounted types then they
          can cause just as much trouble as if they were a simple
          refcounted field.  }
        if (newstate=ris_afterpointer) then
          newstate:=ris_dontprint;
        for i:=0 to recst.symlist.count-1 do
          begin
            if (tsym(recst.symlist[i]).typ<>fieldvarsym) then
              continue;

            field:=tfieldvarsym(recst.symlist[i]);
            if not objcdochecktype(field.vardef,newstate,founderror) then
              exit;
          end;
        result:=true
      end;


    function objcdochecktype(def: tdef; recordinfostate: trecordinfostate; out founderror: tdef): boolean;
      var
        recdef: trecorddef;
        objdef: tobjectdef;
        newstate: trecordinfostate;
      begin
        result:=true;
        case def.typ of
          stringdef :
            begin
              case tstringdef(def).stringtype of
                st_shortstring:
                  ;
                else
                  { While we could handle refcounted Pascal strings correctly
                    when such methods are called from Pascal code, things would
                    completely break down if they were called from Objective-C
                    code/reflection since the necessary refcount helper calls
                    would be missing on the caller side (unless we'd
                    automatically generate wrappers).  }
                  result:=false;
              end;
            end;
          enumdef,
          orddef :
            ;
          pointerdef :
            begin
              newstate:=recordinfostate;
              if (recordinfostate<ris_dontprint) then
                newstate:=succ(newstate);
              if not objcdochecktype(tpointerdef(def).pointeddef,newstate,founderror) then
                begin
                  result:=false;
                  { report the exact (nested) error defintion }
                  exit;
                end;
            end;
          floatdef :
            begin
              case tfloatdef(def).floattype of
                s32real,
                s64real:
                  ;
                else
                  result:=false;
              end;
            end;
          filedef :
            result:=false;
          recorddef :
            begin
              if (recordinfostate<>ris_dontprint) then
                begin
                  if not checkrecsttype(tabstractrecordsymtable(trecorddef(def).symtable),recordinfostate,founderror) then
                    begin
                      result:=false;
                      { report the exact (nested) error defintion }
                      exit;
                    end
                end
            end;
          variantdef :
            begin
              recdef:=trecorddef(search_system_type('TVARDATA').typedef);
              if (recordinfostate<>ris_dontprint) then
                begin
                  if not checkrecsttype(tabstractrecordsymtable(recdef.symtable),recordinfostate,founderror) then
                    begin
                      result:=false;
                      { report the exact (nested) error defintion }
                      exit;
                    end
                end;
            end;
          classrefdef:
            begin
              if is_objcclassref(def) then
                begin
                  objdef:=tobjectdef(tclassrefdef(def).pointeddef);
                  newstate:=recordinfostate;
                  if (recordinfostate<ris_dontprint) then
                    newstate:=succ(newstate);
                  if (newstate<>ris_dontprint) then
                    begin
                      if not checkrecsttype(tabstractrecordsymtable(objdef.symtable),recordinfostate,founderror) then
                        begin
                          result:=false;
                          { report the exact (nested) error defintion }
                          exit;
                        end
                    end
                end
            end;
          setdef,
          formaldef :
            ;
          arraydef :
            begin
              if is_array_of_const(def) then
                { ok, varargs are ignored in signatures }
              else if is_special_array(def) then
                result:=false
              else
                begin
                  if not is_packed_array(def) then
                    begin
                      if not objcdochecktype(tarraydef(def).elementdef,ris_initial,founderror) then
                        begin
                          result:=false;
                          { report the exact (nested) error defintion }
                          exit;
                        end;
                    end;
                end;
            end;
          procvardef :
            ;
          objectdef :
            case tobjectdef(def).objecttype of
              odt_class,
              odt_object,
              odt_cppclass:
                begin
                  newstate:=recordinfostate;
                  { implicit pointer for classes }
                  if (tobjectdef(def).objecttype=odt_class) then
                    begin
                      if (recordinfostate<ris_dontprint) then
                        newstate:=succ(newstate);
                    end;
                  if newstate<>ris_dontprint then
                    begin
                      if not checkrecsttype(tabstractrecordsymtable(tobjectdef(def).symtable),newstate,founderror) then
                        begin
                          result:=false;
                          { report the exact (nested) error defintion }
                          exit;
                        end
                    end
                end;
              odt_interfacecom,
              odt_interfacecom_property,
              odt_interfacecom_function,
              odt_dispinterface:
                result:=false;
              odt_interfacecorba,
              odt_objcclass,
              odt_objcprotocol:
                ;
              else
                internalerror(2009081709);
            end;
          undefineddef,
          errordef :
            result:=false;
          procdef :
            result:=false;
        else
          internalerror(2009170812);
        end;
        if not result then
          founderror:=def;
      end;


    function objcchecktype(def: tdef; out founderror: tdef): boolean;
      begin
        result:=objcdochecktype(def,ris_initial,founderror);
      end;


{******************************************************************
                    ObjC class exporting
*******************************************************************}

    procedure exportobjcclassfields(objccls: tobjectdef);
    var
      i: longint;
      vf: tfieldvarsym;
      prefix: string;
    begin
      prefix:=target_info.cprefix+'OBJC_IVAR_$_'+objccls.objextname^+'.';
      for i:=0 to objccls.symtable.SymList.Count-1 do
        if tsym(objccls.symtable.SymList[i]).typ=fieldvarsym then
          begin
            vf:=tfieldvarsym(objccls.symtable.SymList[i]);
            { TODO: package visibility (private_extern) -- must not be exported
               either}
            if not(vf.visibility in [vis_private,vis_strictprivate]) then
              exportname(prefix+vf.RealName,0);
          end;
    end;


    procedure exportobjcclass(def: tobjectdef);
      begin
        if (target_info.system in system_objc_nfabi) then
          begin
            { export class and metaclass symbols }
            exportname(def.rtti_mangledname(objcclassrtti),0);
            exportname(def.rtti_mangledname(objcmetartti),0);
            { export public/protected instance variable offset symbols }
            exportobjcclassfields(def);
          end
        else
          begin
             { export the class symbol }
             exportname('.objc_class_name_'+def.objextname^,0);
          end;
      end;

end.