Hi,

Unit shlobj has:

       SIGDN      = longint;

But the constants are for example:

SIGDN_FILESYSPATH               = $80058000;

Maybe SIGDN must be DWord?

Mattias

I think it's deliberately designed that way so such codes are negative numbers in signed 32-bit.

Gareth aka. Kit

J. Gareth "Kit" Moreton wrote

I think it's deliberately designed that way so such codes are negative numbers in signed 32-bit.

I spotted it because code fails to compile with a range check error.

Windows docs says these constants are from an enumeration.

Mattias

Hmmm, that's a little bit difficult.  What happens if you define the constants as, say, "SIGDN_FILESYSPATH = longint($80058000);"?

Gareth aka. Kit

J. Gareth "Kit" Moreton wrote

Hmmm, that's a little bit difficult.  What happens if you define the constants as, say, "SIGDN_FILESYSPATH = longint($80058000);"?

Then it would compile.

But it seems the C code uses DWord, so why should FPC use longint?

Mattias

Ah, if you mean that SIGDN is defined as a DWord in its C headers but as a LongInt in FPC, then I think it's due to backwards compatibility back when Turbo Pascal and Delphi didn't have an unsigned 32-bit integer type (LongWord), and so such a hexadecimal constant would default to LongInt.

Gareth aka. Kit

Historic reasons, most likely.
Of course it should not use longint these days, it must be changed to DWord/Cardinal.

Michael.

W dniu 2026-06-25 o 00:51, Mattias Gaertner via fpc-devel pisze:

This is how it's defined in header file:
enum _SIGDN
{
SIGDN_NORMALDISPLAY = 0,
SIGDN_PARENTRELATIVEPARSING = ( int )0x80018001,
SIGDN_DESKTOPABSOLUTEPARSING = ( int )0x80028000, SIGDN_PARENTRELATIVEEDITING = ( int )0x80031001,
SIGDN_DESKTOPABSOLUTEEDITING = ( int )0x8004c000, SIGDN_FILESYSPATH = ( int )0x80058000,
SIGDN_URL = ( int )0x80068000,
SIGDN_PARENTRELATIVEFORADDRESSBAR = ( int )0x8007c001, SIGDN_PARENTRELATIVE = ( int )0x80080001,
SIGDN_PARENTRELATIVEFORUI = ( int )0x80094001

     } 	SIGDN;

It looks like it's a signed integer.

https://github.com/tpn/winsdk-10/blob/9b69fd26ac0c7d0b83d378dba01080e93349c2ed/Include/10.0.16299.0/um/ShObjIdl_core.h#L7904

https://learn.microsoft.com/en-us/windows/win32/api/shobjidl_core/ne-shobjidl_core-sigdn#constants

Michał.

Ah, thx, so the FPC constants need the typecast.

Mattias

Op 25-6-2026 om 11:58 schreef Mattias Gaertner via fpc-devel:

Shall I change the definition of constants in the header to longint($8000..) ?