Add `x86_64-unikraft-linux-musl` target
This introduces `x86_64-unikraft-linux-musl` as the first Rust target for the [Unikraft] Unikernel Development Kit.
[Unikraft]: https://unikraft.org/
Unikraft imitates Linux and uses musl as libc.
It is extremely configurable, and does not even provide a `poll` implementation or a network stack, unless enabled by the end user who compiles the application.
Our approach for integrating the build process with `rustc` is to hide the build process as well as the actual final linking step behind a linker-shim (`kraftld`, see https://github.com/unikraft/kraftkit/issues/612).
## Tier 3 target policy
> - A tier 3 target must have a designated developer or developers (the "target
> maintainers") on record to be CCed when issues arise regarding the target.
> (The mechanism to track and CC such developers may evolve over time.)
I will be the target maintainer.
> - Targets must use naming consistent with any existing targets; for instance, a
> target for the same CPU or OS as an existing Rust target should use the same
> name for that CPU or OS. Targets should normally use the same names and
> naming conventions as used elsewhere in the broader ecosystem beyond Rust
> (such as in other toolchains), unless they have a very good reason to
> diverge. Changing the name of a target can be highly disruptive, especially
> once the target reaches a higher tier, so getting the name right is important
> even for a tier 3 target.
> - Target names should not introduce undue confusion or ambiguity unless
> absolutely necessary to maintain ecosystem compatibility. For example, if
> the name of the target makes people extremely likely to form incorrect
> beliefs about what it targets, the name should be changed or augmented to
> disambiguate it.
> - If possible, use only letters, numbers, dashes and underscores for the name.
> Periods (`.`) are known to cause issues in Cargo.
The target name `x86_64-unikraft-linux-musl` was derived from `x86_64-unknown-linux-musl`, setting Unikraft as vendor.
Unikraft exactly imitates Linux + musl.
> - Tier 3 targets may have unusual requirements to build or use, but must not
> create legal issues or impose onerous legal terms for the Rust project or for
> Rust developers or users.
> - The target must not introduce license incompatibilities.
> - Anything added to the Rust repository must be under the standard Rust
> license (`MIT OR Apache-2.0`).
> - The target must not cause the Rust tools or libraries built for any other
> host (even when supporting cross-compilation to the target) to depend
> on any new dependency less permissive than the Rust licensing policy. This
> applies whether the dependency is a Rust crate that would require adding
> new license exceptions (as specified by the `tidy` tool in the
> rust-lang/rust repository), or whether the dependency is a native library
> or binary. In other words, the introduction of the target must not cause a
> user installing or running a version of Rust or the Rust tools to be
> subject to any new license requirements.
> - Compiling, linking, and emitting functional binaries, libraries, or other
> code for the target (whether hosted on the target itself or cross-compiling
> from another target) must not depend on proprietary (non-FOSS) libraries.
> Host tools built for the target itself may depend on the ordinary runtime
> libraries supplied by the platform and commonly used by other applications
> built for the target, but those libraries must not be required for code
> generation for the target; cross-compilation to the target must not require
> such libraries at all. For instance, `rustc` built for the target may
> depend on a common proprietary C runtime library or console output library,
> but must not depend on a proprietary code generation library or code
> optimization library. Rust's license permits such combinations, but the
> Rust project has no interest in maintaining such combinations within the
> scope of Rust itself, even at tier 3.
> - "onerous" here is an intentionally subjective term. At a minimum, "onerous"
> legal/licensing terms include but are *not* limited to: non-disclosure
> requirements, non-compete requirements, contributor license agreements
> (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms,
> requirements conditional on the employer or employment of any particular
> Rust developers, revocable terms, any requirements that create liability
> for the Rust project or its developers or users, or any requirements that
> adversely affect the livelihood or prospects of the Rust project or its
> developers or users.
No dependencies were added to Rust.
Requirements for linking are [Unikraft] and [KraftKit] (both BSD-3-Clause), but none of these are added to Rust.
[KraftKit]: https://github.com/unikraft/kraftkit
> - Neither this policy nor any decisions made regarding targets shall create any
> binding agreement or estoppel by any party. If any member of an approving
> Rust team serves as one of the maintainers of a target, or has any legal or
> employment requirement (explicit or implicit) that might affect their
> decisions regarding a target, they must recuse themselves from any approval
> decisions regarding the target's tier status, though they may otherwise
> participate in discussions.
> - This requirement does not prevent part or all of this policy from being
> cited in an explicit contract or work agreement (e.g. to implement or
> maintain support for a target). This requirement exists to ensure that a
> developer or team responsible for reviewing and approving a target does not
> face any legal threats or obligations that would prevent them from freely
> exercising their judgment in such approval, even if such judgment involves
> subjective matters or goes beyond the letter of these requirements.
Understood.
I am not a member of a Rust team.
> - Tier 3 targets should attempt to implement as much of the standard libraries
> as possible and appropriate (`core` for most targets, `alloc` for targets
> that can support dynamic memory allocation, `std` for targets with an
> operating system or equivalent layer of system-provided functionality), but
> may leave some code unimplemented (either unavailable or stubbed out as
> appropriate), whether because the target makes it impossible to implement or
> challenging to implement. The authors of pull requests are not obligated to
> avoid calling any portions of the standard library on the basis of a tier 3
> target not implementing those portions.
Understood.
`std` is supported.
> - The target must provide documentation for the Rust community explaining how
> to build for the target, using cross-compilation if possible. If the target
> supports running binaries, or running tests (even if they do not pass), the
> documentation must explain how to run such binaries or tests for the target,
> using emulation if possible or dedicated hardware if necessary.
Building is described in the platform support doc.
It will be updated once proper `kraftld` support has landed.
> - Tier 3 targets must not impose burden on the authors of pull requests, or
> other developers in the community, to maintain the target. In particular,
> do not post comments (automated or manual) on a PR that derail or suggest a
> block on the PR based on a tier 3 target. Do not send automated messages or
> notifications (via any medium, including via ``@`)` to a PR author or others
> involved with a PR regarding a tier 3 target, unless they have opted into
> such messages.
> - Backlinks such as those generated by the issue/PR tracker when linking to
> an issue or PR are not considered a violation of this policy, within
> reason. However, such messages (even on a separate repository) must not
> generate notifications to anyone involved with a PR who has not requested
> such notifications.
Understood.
> - Patches adding or updating tier 3 targets must not break any existing tier 2
> or tier 1 target, and must not knowingly break another tier 3 target without
> approval of either the compiler team or the maintainers of the other tier 3
> target.
> - In particular, this may come up when working on closely related targets,
> such as variations of the same architecture with different features. Avoid
> introducing unconditional uses of features that another variation of the
> target may not have; use conditional compilation or runtime detection, as
> appropriate, to let each target run code supported by that target.
I don't think this PR breaks anything.
r? compiler-team
fix docs & example for `std::os::unix::prelude::FileExt::write_at`
Changelog:
* used `File::create` instead of `File::read` to get a writeable file
* explicity mentioned the bug with `pwrite64` in docs
Unfortunately, I don't think that there is really much we can do about this since the feature has already been stabilised.
We could potentially add a clippy lint warning people on Linux that using `write_at` with the `O_APPEND` flag does not exhibit the behaviour that they would have assumed.
fixes#113627
Allow limited access to `OsString` bytes
This extends #109698 to allow no-cost conversion between `Vec<u8>` and `OsString` as suggested in feedback from `os_str_bytes` crate in #111544.
std: remove an allocation in `Path::with_extension`
`Path::with_extension` used to reallocate (and copy) paths twice per call, now it does it once, by checking the size of the previous and new extensions it's possible to call `PathBuf::with_capacity` and pass the exact capacity required.
This also reduces the memory consumption of the path returned from `Path::with_extension` by using exact capacity instead of using amortized exponential growth.
Update documentation for std::process::Command's new method
In the current documentation, it's not specified that when creating a Command, the .exe extension can be omitted for Windows executables. However, for other types of executable files like .bat or .cmd, the complete filename including the extension must be provided.
I encountered it by noticing that `Command::new("wt").spawn().unwrap()` succeeds on my machine while `Command::new("code").spawn().unwrap()` panics. Turns out VS Code's entrypoint is .cmd file.
`resolve_exe` method mentions this behaviour in [a comment](e7fda447e7/library/std/src/sys/windows/process.rs (L425)), but it makes sense to mention it at a more visible place.
I've added this clarification to the documentation, which should make it more accurate and helpful for Rust developers working on the Windows platform.
Implement rust-lang/compiler-team#578.
When an ICE is encountered on nightly releases, the new rustc panic
handler will also write the contents of the backtrace to disk. If any
`delay_span_bug`s are encountered, their backtrace is also added to the
file. The platform and rustc version will also be collected.
In the current documentation, it's not specified that when creating
a Command, the .exe extension can be omitted for Windows executables.
However, for other types of executable files like .bat or .cmd,
the complete filename including the extension must be provided.
I encountered it by noticing that `Command::new("wt").spawn().unwrap()`
succeeds on my machine while `Command::new("code").spawn().unwrap()`
panics. Turns out VS Code's entrypoint is .cmd file.
`resolve_exe` method mentions this behaviour in a comment[1], but it
makes sense to mention it at more visible place.
I've added this clarification to the documentation, which should
make it more accurate and helpful for Rust developers
working on the Windows platform.
[1] e7fda447e7/library/std/src/sys/windows/process.rs (L425)
Like the other CStr and CString error types, make a re-export for
std::ffi::FromBytesUntilNulError.
This seems to have slipped through the cracks in the
cstr_from_bytes_until_nul implementation and core_c_str migration.
Tracking Issue: #95027
Adjustments for RustyHermit
The interface between `libstd` and the OS changed and some changes are not correctly merged for RustHermit. For instance, the crate `hermit_abi` isn't defined as public, although it provided the socket interface for the application.
In addition, the support of thread::available_parallelism is realized. It returns the number of available processors.
Add `Read`, `Write` and `Seek` impls for `Arc<File>` where appropriate
If `&T` implements these traits, `Arc<T>` has no reason not to do so
either. This is useful for operating system handles like `File` or
`TcpStream` which don't need a mutable reference to implement these
traits.
CC #53835.
CC #94744.
move pal cfgs in f32 and f64 to sys
I'd like to push forward on `sys` being a separate crate. To start with, most of these PAL exception cases are very simple little bits of code like this, so I thought I would try tidying them up.
Revert the lexing of `c"…"` string literals
Fixes \[after beta-backport\] #113235.
Further progress is tracked in #113333.
This PR *manually* reverts parts of #108801 (since a git-revert would've been too coarse-grained & messy)
and git-reverts #111647.
CC `@fee1-dead` (#108801) `@klensy` (#111647)
r? `@compiler-errors`
`@rustbot` label F-c_str_literals beta-nominated
`Path::with_extension` used to reallocate (and copy) paths twice per
call, now it does it once, by checking the size of the previous and new
extensions it's possible to call `PathBuf::with_capacity` and pass the
exact capacity it takes.
Also reduce the memory consumption of the path returned from
`Path::with_extension` by using exact capacity instead of using
amortized exponential growth.
Move windows-sys arm32 shim to c.rs
This moves the arm32 shim in to c.rs instead of appending to the generated file itself.
This makes it simpler to change these workarounds if/when needed. The downside is we need to exclude a couple of functions from being generated (see the comment). A metadata solution could help here but they'll be easy enough to add back if that happens.
Remove unnecessary `path` attribute
Follow up to #111401. I missed this at the time but it should now be totally unnecessary since the other include was removed.
r? `@workingjubilee`
Expose `compiler-builtins-weak-intrinsics` feature for `-Zbuild-std`
This was added in rust-lang/compiler-builtins#526 to force all compiler-builtins intrinsics to use weak linkage.
Implement `Sync` for `mpsc::Sender`
`mpsc::Sender` is currently `!Sync` because the previous implementation contained an optimization where the channel started out as single-producer and was dynamically upgraded on the first clone, which relied on a unique reference to the sender. This optimization is one of the main reasons the old implementation was so complex and was removed in #93563. `mpsc::Sender` can now soundly implement `Sync`.
Note for any potential confusion, this chance does *not* add MPMC behavior. This only affects the already `Send + Clone` *sender*, not *receiver*.
It's technically possible to rely on the `!Sync` behavior in the same way as a `PhantomData<*mut T>`, but that seems very unlikely in practice. Either way, this change is insta-stable and needs an FCP.
`@rustbot` label +T-libs-api -T-libs
If `&T` implements these traits, `Arc<T>` has no reason not to do so
either. This is useful for operating system handles like `File` or
`TcpStream` which don't need a mutable reference to implement these
traits.
CC #53835.
CC #94744.
Document memory orderings of `thread::{park, unpark}`
Document `thread::park/unpark` as having acquire/release synchronization. Without that guarantee, even the example in the documentation can deadlock:
```rust
let flag = Arc::new(AtomicBool::new(false));
let t2 = thread::spawn(move || {
while !flag.load(Ordering::Acquire) {
thread::park();
}
});
flag.store(true, Ordering::Release);
t2.thread().unpark();
// t1: flag.store(true)
// t1: thread.unpark()
// t2: flag.load() == false
// t2 now parks, is immediately unblocked but never
// acquires the flag, and thus spins forever
```
Multiple calls to `unpark` should also maintain a release sequence to make sure operations released by previous `unpark`s are not lost:
```rust
let a = Arc::new(AtomicBool::new(false));
let b = Arc::new(AtomicBool::new(false));
let t2 = thread::spawn(move || {
while !a.load(Ordering::Acquire) || !b.load(Ordering::Acquire) {
thread::park();
}
});
thread::spawn(move || {
a.store(true, Ordering::Release);
t2.thread().unpark();
});
b.store(true, Ordering::Release);
t2.thread().unpark();
// t1: a.store(true)
// t1: t2.unpark()
// t3: b.store(true)
// t3: t2.unpark()
// t2 now parks, is immediately unblocked but never
// acquires the store of `a`, only the store of `b` which
// was released by the most recent unpark, and thus spins forever
```
This is of course a contrived example, but is reasonable to rely upon in real code.
Note that all implementations of park/unpark already comply with the rules, it's just undocumented.
std: only depend on dlmalloc for wasm*-unknown
It was already filtered out for emscripten, but wasi doesn't need dlmalloc
either since it reuses `unix/alloc.rs`.
io: soften ‘at most one write attempt’ requirement in io::Write::write
At the moment, documentation of std::io::Write::write indicates that
call to it ‘represents at most one attempt to write to any wrapped
object’. It seems that such wording was put there to contrast it with
pre-1.0 interface which attempted to write all the data (it has since
been changed in [RFC 517]).
However, the requirement puts unnecessary constraints and may
complicate adaptors which perform non-trivial transformations on the
data. For example, they may maintain an internal buffer which needs
to be written out before the write method accepts more data. It might
be natural to code the method such that it flushes the buffer and then
grabs another chunk of user data. With the current wording in the
documentation, the adaptor would be forced to return Ok(0).
This commit softens the wording such that implementations can choose
code structure which makes most sense for their particular use case.
While at it, elaborate on the meaning of `Ok(0)` return pointing out
that the write_all methods interprets it as an error.
[RFC 517]: https://rust-lang.github.io/rfcs/0517-io-os-reform.html
fix: get the l4re target working again
This is based on work from https://github.com/rust-lang/rust/pull/103966, addressing the review comment by `@m-ou-se` at the time and "fixing" the (probably newly) missing read_buf.
Rollup of 6 pull requests
Successful merges:
- #112352 (Fix documentation build on FreeBSD)
- #112644 (Correct types in method descriptions of `NonZero*` types)
- #112683 (fix ICE on specific malformed asm clobber_abi)
- #112707 ([rustdoc] Fix invalid handling of "going back in history" when "go to only search result" setting is enabled)
- #112719 (Replace fvdl with ffx, allow test without install)
- #112728 (Add `<meta charset="utf-8">` to `-Zdump-mir-spanview` output)
r? `@ghost`
`@rustbot` modify labels: rollup
Fix documentation build on FreeBSD
After the socket ancillary data implementation was introduced, the documentation build was broken on FreeBSD hosts, add the same workaround as for the existing implementations.
Fixes the doc build after #91793
previously it was only able to use BufWriter. This was due to a limitation in the
BufReader generics that prevented specialization. This change works around the issue
by using `where Self: Read` instead of `where I: Read`. This limits our options, e.g.
we can't access BufRead methods, but it happens to work out if we rely on some
implementation details.
Fix building libstd documentation on FreeBSD.
It fixes the following error:
```
error[E0412]: cannot find type `sockcred2` in module `libc`
--> library/std/src/os/unix/net/ancillary.rs:211:29
|
211 | pub struct SocketCred(libc::sockcred2);
| ^^^^^^^^^ not found in `libc`
```
