This is related to issue #24907.
In the comment I explain the problem :
http://bugs.freepascal.org/view.php?id=24907#c71475 but I copy it also here below.
Now, is it a bug or feature?
Otherwise not a big deal but CodeTools follow FPC behavior and the Delphi converter uses CodeTools. Apparently valid Delphi code cannot be converted because of this problem.

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Neither codetools nor FPC 2.6.2 supports the "operator <" syntax in {$mode delphi}. It is ok in {$mode objfpc}.
Try to code complete and compile the code below. Then try again with {$mode objfpc}.
How does FPC trunk behave?
If the syntax is indeed supported by Delphi then this is a bug in FPC's mode delphi. Codetools only follows the syntax rules of FPC. Who will open a report for FPC?

-----------------------
unit Unit2;
{$mode delphi}
interface
type
  TRootMove = record
    score: integer;
    node_count: uint64;
  end;
  operator < (m1, m2: TRootMove) LessThan : Boolean;
implementation
operator < (m1, m2: TRootMove) LessThan : Boolean;
begin
  if m1.score  m2.score then
    result := m1.score < m2.score
  else
    result := m1.node_count < m2.node_count;
end;
end.

Neither global operators nor symbolic (<, >, etc.) operator names are supported by Delphi.

Regards,
Sven

Sven Barth wrote

Neither global operators nor symbolic (<, >, etc.) operator names are supported by Delphi.

You are right.
Now looking more carefully at the example critterchess code : http://sourceforge.net/projects/critterchess
it is already partly ported for FPC. There is no Lazarus project but the code has IFDEFs:

{$ifndef FPC}
class operator TRootMove.LessThan(m1, m2: TRootMove): boolean;
{$else}
operator < (m1, m2: TRootMove) LessThan : boolean;
{$endif}

The converter defines Mode Delphi and FPC is already defined. The result is illegal code.
This is a good example of a strange code variation the converter gets. It cannot tackle all of them.

Juha