Delphi – E2009 Incompatible types – ‘%s’

Posted by AbundantCode

A distinction between the declaration and use of a procedure has been discovered by the compiler.

program Produce;

  type
    ProcedureParm0 = procedure; stdcall;
    ProcedureParm1 = procedure(VAR x : Integer);

  procedure WrongConvention; register;
  begin
  end;

  procedure WrongParms(x, y, z : Integer);
  begin
  end;

  procedure TakesParm0(p : ProcedureParm0);
  begin
  end;

  procedure TakesParm1(p : ProcedureParm1);
  begin
  end;

begin
  TakesParm0(WrongConvention);
  TakesParm1(WrongParms);
end.

Because the type ‘ProcedureParm0′ expects a’stdcall’ procedure, but ‘WrongConvention’ is declared with the’register’ calling convention, the call to ‘TakesParm0’ will result in an error. Similarly, because the parameter lists do not match, the call to ‘TakesParm1’ will fail.

program Solve;

  type
    ProcedureParm0 = procedure; stdcall;
    ProcedureParm1 = procedure(VAR x : Integer);

  procedure RightConvention; stdcall;
  begin
  end;

  procedure RightParms(VAR x : Integer);
  begin
  end;

  procedure TakesParm0(p : ProcedureParm0);
  begin
  end;

  procedure TakesParm1(p : ProcedureParm1);
  begin
  end;

begin
  TakesParm0(RightConvention);
  TakesParm1(RightParms);
end.

Both of these issues can be solved by ensuring that the calling convention or parameter lists match the declaration.

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