STD support for the Nintendo 3DS
Rustc already supports compiling for the Nintendo 3DS using the `armv6k-nintendo-3ds` target (Tier 3). Until now though, only `core` and `alloc` were supported. This PR adds standard library support for the Nintendo 3DS. A notable exclusion is `std::thread` support, which will come in a follow-up PR as it requires more complicated changes.
This has been a joint effort by `@Meziu,` `@ian-h-chamberlain,` myself, and prior work by `@rust3ds` members.
### Background
The Nintendo 3DS (Horizon OS) is a mostly-UNIX looking system, with the caveat that it does not come with a full libc implementation out of the box. On the homebrew side (I'm not under NDA), the libc interface is partially implemented by the [devkitPro](https://devkitpro.org/wiki/devkitPro_pacman) toolchain and a user library like [`libctru`](https://github.com/devkitPro/libctru). This is important because there are [some possible legal barriers](https://github.com/rust-lang/rust/pull/88529#issuecomment-919938396) to linking directly to a library that uses the underlying platform APIs, since they might be considered a trade secret or under NDA.
To get around this, the standard library impl for the 3DS does not directly depend on any platform-level APIs. Instead, it expects standard libc functions to be linked in. The implementation of these libc functions is left to the user. Some functions are provided by the devkitPro toolchain, but in our testing, we used the following to fill in the other functions:
- [`libctru`] - provides more basic APIs, such as `nanosleep`. Linked in by way of [`ctru-sys`](https://github.com/Meziu/ctru-rs/tree/master/ctru-sys).
- [`pthread-3ds`](https://github.com/Meziu/pthread-3ds) - provides pthread APIs for `std::thread`. Implemented using [`libctru`].
- [`linker-fix-3ds`](https://github.com/Meziu/rust-linker-fix-3ds) - fulfills some other missing libc APIs. Implemented using [`libctru`].
For more details, see the `src/doc/rustc/src/platform-support/armv6k-nintendo-3ds.md` file added in this PR.
### Notes
We've already upstreamed changes to the [`libc`] crate to support this PR, as well as the upcoming threading PR. These changes have all been released as of 0.2.121, so we bump the crate version in this PR.
Edit: After some rebases, the version bump has already been merged so it doesn't appear in this PR.
A lot of the changes in this PR are straightforward, and follow in the footsteps of the ESP-IDF target: https://github.com/rust-lang/rust/pull/87666.
The 3DS does not support user space process spawning, so these APIs are unimplemented (similar to ESP-IDF).
[`libctru`]: https://github.com/devkitPro/libctru
[`libc`]: https://github.com/rust-lang/libc
Remove `#[rustc_deprecated]`
This removes `#[rustc_deprecated]` and introduces diagnostics to help users to the right direction (that being `#[deprecated]`). All uses of `#[rustc_deprecated]` have been converted. CI is expected to fail initially; this requires #95958, which includes converting `stdarch`.
I plan on following up in a short while (maybe a bootstrap cycle?) removing the diagnostics, as they're only intended to be short-term.
As discussed here
https://github.com/rust-lang/rust/pull/88300#issuecomment-936085371
exit is (conventionally) a library function, with _exit being the
actual system call.
I have checked the other references and they say "if the process
terminated by calling `exti`". I think despite the slight
imprecision (strictly, it should read iff ... `_exit`), this is
clearer. Anyone who knows about the distinction between `exit` and
`_exit` will not be confused.
`_exit` is the correct traditional name for the system call, despite
Linux calling it `exit_group` or `exit`:
https://www.freebsd.org/cgi/man.cgi?query=_exit&sektion=2&n=1
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Stabilise unix_process_wait_more, extra ExitStatusExt methods
This stabilises the feature `unix_process_wait_more`. Tracking issue #80695, FCP needed.
This was implemented in #79982 and merged in January.
Provide ExitStatusError
Closes#73125
In MR #81452 "Add #[must_use] to [...] process::ExitStatus" we concluded that the existing arrangements in are too awkward so adding that `#[must_use]` is blocked on improving the ergonomics.
I wrote a mini-RFC-style discusion of the approach in https://github.com/rust-lang/rust/issues/73125#issuecomment-771092741
It is unergnomic to have to say things like
bad.into_status().signal()
Implementing `ExitStatusExt` for `ExitStatusError` fixes this.
Unfortunately it does mean making a previously-infallible method
capable of panicing, although of course the existing impl remains
infallible.
The alternative would be a whole new `ExitStatusErrorExt` trait.
`<ExitStatus as ExitStatusExt>::into_raw()` is not particularly
ergonomic to call because of the often-required type annotation.
See for example the code in the test case in
library/std/src/sys/unix/process/process_unix/tests.rs
Perhaps we should provide equivalent free functions for `ExitStatus`
and `ExitStatusExt` in std::os::unix::process and maybe deprecate this
trait method. But I think that is for the future.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
