SetWindowLongPtrW documentation expects isize, compilation fails expecting i32 (i686-pc-windows-msvc)

[LGUG2Z]

Summary

The docs state that SetWindowLongPtrW's final argument should take an isize: https://microsoft.github.io/windows-docs-rs/doc/windows/Win32/UI/WindowsAndMessaging/fn.SetWindowLongPtrW.html

When compiling against stable-i686-pc-windows-msvc, a compilation error suggests that an i32 is expected:

cargo +stable-i686-pc-windows-msvc build

error[E0308]: mismatched types
    --> src/main.rs:8:72
     |
8    |         SetWindowLongPtrW(HWND::default(), WINDOW_LONG_PTR_INDEX(-20), 1_isize);
     |         ----------------- arguments to this function are incorrect     ^^^^^^^ expected `i32`, found `isize`
     |
note: function defined here
    --> C:\Users\LGUG2Z\.cargo\registry\src\index.crates.io-1cd66030c949c28d\windows-0.58.0\src\Windows\Win32\UI\WindowsAndMessaging\mod.rs:3034:15
     |
3034 | pub unsafe fn SetWindowLongW<P0>(hwnd: P0, nindex: WINDOW_LONG_PTR_INDEX, dwnewlong: i32) -> i32
     |               ^^^^^^^^^^^^^^
help: change the type of the numeric literal from `isize` to `i32`
     |
8    |         SetWindowLongPtrW(HWND::default(), WINDOW_LONG_PTR_INDEX(-20), 1_i32);
     |                                                                          ~~~

For more information about this error, try `rustc --explain E0308`.
error: could not compile `winrs-repro` (bin "winrs-repro") due to 1 previous error

Compilation against stable-x86_64-pc-windows-msvc succeeds as expected.

Crate manifest

[package]
name = "winrs-repro"
version = "0.1.0"
edition = "2021"

[dependencies]

[dependencies.windows]
version = "0.58"
features = [
    "Win32_Foundation",
    "Win32_UI_WindowsAndMessaging",
]

Crate code

use windows::Win32::{
    Foundation::HWND,
    UI::WindowsAndMessaging::{SetWindowLongPtrW, WINDOW_LONG_PTR_INDEX},
};

fn main() {
    unsafe {
        SetWindowLongPtrW(HWND::default(), WINDOW_LONG_PTR_INDEX(-20), 1_isize);
    }
}

[kennykerr]

That's because SetWindowLongPtrW does not actually exist on 32-bit builds of Windows, but as a convenience it is defined in terms of SetWindowLongW to make it easier to target both 32-bit and 64-bit builds.

windows-rs/crates/libs/windows/src/includes/Win32/UI/WindowsAndMessaging/WindowLong.rs

Lines 1 to 8 in 622d8bd

	#[cfg(target_pointer_width = "32")]
	pub use GetWindowLongA as GetWindowLongPtrA;
	#[cfg(target_pointer_width = "32")]
	pub use GetWindowLongW as GetWindowLongPtrW;
	#[cfg(target_pointer_width = "32")]
	pub use SetWindowLongA as SetWindowLongPtrA;
	#[cfg(target_pointer_width = "32")]
	pub use SetWindowLongW as SetWindowLongPtrW;