Implement ExitCodeExt for Windows by AronParker · Pull Request #97917 · rust-lang/rust (original) (raw)

Motivation:

On Windows it is common for applications to return HRESULT (i32) or DWORD (u32) values. These stem from COM based components (HRESULTS), Win32 errors (GetLastError), GUI applications (WM_QUIT) and more. The newly stabilized ExitCode provides an excellent fit for propagating these values, because std::process::exit does not run deconstructors which can result in errors. However, ExitCode currently only implements From<u8> for ExitCode, which disallows the full range of i32/u32 values. This pull requests attempts to address that shortcoming by providing windows specific extensions that accept a u32 value (which covers all possible HRESULTS and Win32 errors) analog to ExitStatusExt::from_raw.

This was also intended by the original Stabilization #93840 (comment) as pointed out by @eggyal in #97914 (comment):

Issues around platform specific representations: We resolved this issue by changing the return type of report from i32 to the opaque type ExitCode. That way we can change the underlying representation without affecting the API, letting us offer full support for platform specific exit code APIs in the future.

[Emphasis added]

API

/// Windows-specific extensions to [process::ExitCode]. /// /// This trait is sealed: it cannot be implemented outside the standard library. /// This is so that future additional methods are not breaking changes. #[stable(feature = "windows_process_exit_code_from", since = "1.63.0")] pub trait ExitCodeExt: Sealed { /// Creates a new ExitCode from the raw underlying u32 return value of /// a process. #[stable(feature = "windows_process_exit_code_from", since = "1.63.0")] fn from_raw(raw: u32) -> Self; }

#[stable(feature = "windows_process_exit_code_from", since = "1.63.0")] impl ExitCodeExt for process::ExitCode { fn from_raw(raw: u32) -> Self { process::ExitCode::from_inner(From::from(raw)) } }

Misc

I apologize in advance if I misplaced any attributes regarding stabilzation, as far as I learned traits are insta-stable so I chose to make them stable. If this is an error, please let me know and I'll correct it. I also added some additional machinery to make it work, analog to ExitStatus.

EDIT: Proposal: rust-lang/libs-team#48