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Strange conflict between NSProcessInfo and NSScreen, causing segmentation fault. #107
Description
I found a strange conflict issue between NSScreen and NSProcessInfo. Using both NSProcessInfo.operatingSystemVersion and UIScreen.mainScreen will cause the application to crash with "segmentation fault". But I can't imagine the relation between them.
Minimal Example:
#[macro_use]
extern crate objc;
use cocoa::{appkit::NSScreen, base::nil};
use objc::{runtime::Object};
fn main() {
unsafe {
let ns_process_info = class!(NSProcessInfo);
let process_info: *mut Object = msg_send![ns_process_info, processInfo];
// Deleting either of the following two lines will avoid the crash.
let os_version: *const Object = msg_send![process_info, operatingSystemVersion];
let screen = NSScreen::mainScreen(nil);
}
}[package]
name = "rsplg"
version = "0.1.0"
edition = "2018"
[dependencies]
cocoa = "0.24"
objc = "0.2.7"
objc-foundation = "0.1"
Activity
madsmtm commentedon Oct 14, 2021
msg_send!has no way to know what sending theoperatingSystemVersionselector toNSProcessInfocould possibly return, so when you writelet os_version: *const Object, you have the responsibility to ensure that the return type is correct. When it isn't you get to keep both pieces (this isunsafecode after all).In this case,
operatingSystemVersiondoes not return an instance pointer (*const Object), the return type is a structNSOperatingSystemVersionwith three integers (found out by looking at C header files and the documentation).So the correct usage would be: