Understanding the correct syntax for importing functions with v7

[Andrew Truckle]

I have this import:

function SetWindowLongPtr(
  hWnd: HWND;
  nIndex: Integer;
  dwNewLong: NativeInt): NativeInt;
  external 'SetWindo...@user32.dll stdcall';

According to the official docus:

LONG_PTR SetWindowLongPtrW(
  [in] HWND     hWnd,
  [in] int      nIndex,
  [in] LONG_PTR dwNewLong
);

This compiles fine for 64 bit installers but fails to work properly for 32 bit installers:

[15:01:16.605]   Function and DLL name: SetWindo...@user32.dll
[15:01:16.607]   Importing the DLL function. Dest DLL name: user32.dll
[15:01:16.611]   Failed to import the DLL function (127).

I am sorry if I have overlooked an explanation. Thank you.

[Andrew Truckle]

Note that the system obscured the code as it though it was an email address.

SetWindowLongPtrW @ user32.dll

[Martijn Laan]

Hi,

SetWindowLongPtrW doesn't exist in 32-bit Windows. It only has SetWindowLongW.

Greetings,
Martijn

Op 17-3-2026 om 16:11 schreef Andrew Truckle:

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[Andrew Truckle]

Ok so why does the Inno 6 installer work without any errors? Why has it become a problem now? But thanks and I will try as you suggested 

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[Andrew Truckle]

According to:

https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setwindowlongw

It states:

---

Note  This function has been superseded by the SetWindowLongPtr function. To write code that is compatible with both 32-bit and 64-bit versions of Windows, use the SetWindowLongPtr function.
---

So I am confused now.

[Andrew Truckle]

This works:

#ifdef WIN64

function SetWindowLongPtr(
  hWnd: HWND;
  nIndex: Integer;
  dwNewLong: NativeInt): NativeInt;

  external 'SetWindowLongPtrW @ user32.dll stdcall';
#else

function SetWindowLongPtr(
  hWnd: HWND;
  nIndex: Integer;
  dwNewLong: NativeInt): NativeInt;

  external 'SetWindowLongW @ user32.dll stdcall';
#endif

[Martijn Laan]

Hi,

Op 17-3-2026 om 17:59 schreef Andrew Truckle:

Ok so why does the Inno 6 installer work without any errors?

It doesn't. The import you posted doesn't work in Inno Setup 6 or any other version because there simply is no SetWindowLongPtrW function in 32-bit user32.dll. Also Inno Setup 6 doesn't compile the NativeInt type you used.

Note  This function has been superseded by the SetWindowLongPtr function. To write code that is compatible with both 32-bit and 64-bit versions of Windows, use the SetWindowLongPtr function

SetWindowLongPtr is a macro/alias which your compiler translates to the actual function in user32.dll, which is not named that.

Greetings,
Martijn

[Andrew Truckle]

Yep. All understood now. 

Thank you. 

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