Hello,
Consider the following types:
TPuts1 = procedure; cdecl varargs;
TPuts2 = procedure(par: string); cdecl varargs;
TPuts3 = procedure(const par: string); cdecl varargs;
this procedure:
procedure Puts(par1, par2, par3: string); cdecl;
begin
Write(par1, ' ');
Write(par2, ' ');
Write(par3, ' ');
Writeln('');
end;
and this callings:
var
PutsX: Pointer;
begin
TPuts1(@Puts)('Hello1', 'World1', 'HogeMoge1');
TPuts2(@Puts)('Hello2', 'World2', 'HogeMoge2');
TPuts3(@Puts)('Hello3', 'World3', 'HogeMoge3');
PutsX := @Puts;
TPuts1(PutsX)('Hello4', 'World4', 'HogeMoge4');
TPuts2(PutsX)('Hello5', 'World5', 'HogeMoge5');
TPuts2(PutsX)('Hello6', 'World6', 'HogeMoge6');
Readln;
end.
It compiles fine on Delphi, but in FPC I got the following error:
'Wrong number of parameters specified for call to "<Procedure Variable>"'.
OK, I just commented the wrong lines to be able to compile that:
begin
// TPuts1(@Puts)('Hello1', 'World1', 'HogeMoge1');
TPuts2(@Puts)('Hello2', 'World2', 'HogeMoge2');
TPuts3(@Puts)('Hello3', 'World3', 'HogeMoge3');
PutsX := @Puts;
// TPuts1(PutsX)('Hello4', 'World4', 'HogeMoge4');
TPuts2(PutsX)('Hello5', 'World5', 'HogeMoge5');
TPuts2(PutsX)('Hello6', 'World6', 'HogeMoge6');
Readln;
end.
But, after compile it in FPC and run the program, I got a SIGSEGV with the
following stack trace (compiled on Delphi it runs properly):
#0 SYSTEM_$$_SPTR$$POINTER at :0
#1 fpc_ansistr_incr_ref at :0
#2 PUTS(<error reading variable>, <error reading variable>, <error reading
variable>) at project1.lpr:14
#3 main at project1.lpr:25
However, if you declare it using integers, it compiles and works fine in
both compilers:
TPuts = procedure(p0: Integer); cdecl varargs;
procedure Puts(p1, p2, p3: Integer); cdecl;
begin
WriteLn(p1, p2, p3);
end;
begin
TPuts(@Puts)(1, 2, 3);
Below the generated asm to check why the first calling doesn't work in FPC
if the params was declared as strings:
{$IFDEF FPC}
{$MODE DELPHI}
{$ENDIF}
TPuts = procedure(const p0: string); cdecl varargs;
procedure Puts(const p1, p2, p3: string); cdecl;
begin
WriteLn(p1, p2, p3);
end;
begin
TPuts(@Puts)('1', '2', '3');
[FPC]
project1.lpr:17 TPuts(@Puts)('1', '2', '3');
004015B9 6a33 push $0x33
004015BB 6a32 push $0x32
004015BD b810b04000 mov $0x40b010,%eax
004015C2 50 push %eax
004015C3 b850154000 mov $0x401550,%eax
004015C8 ffd0 call *%eax
004015CA 83c40c add $0xc,%esp
[/FPC]
[DELPHI]
Project1.dpr.17: TPuts(@Puts)('1', '2', '3');
004060D4 6A33 push $33
004060D6 6A32 push $32
004060D8 6808614000 push $00406108
004060DD B86C5B4000 mov eax,$00405b6c
004060E2 FFD0 call eax
004060E4 83C40C add esp,$0c
[/DELPHI]
What I'm doing wrong? Can I use this callings on FPC in the DELPHI mode?!
:-/
--
Silvio Clécio
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