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Auto merge of #128469 - matthiaskrgr:rollup-00svite, r=matthiaskrgr

Browse Source 
Rollup of 6 pull requests

Successful merges:

 - #127567 (std: implement the `once_wait` feature)
 - #128162 (Cleanup sys module to match house style)
 - #128296 (Update target-spec metadata for loongarch64 targets)
 - #128443 (Properly mark loop as diverging if it has no breaks)
 - #128449 (Temporarily switch `ambiguous_negative_literals` lint to allow)
 - #128452 (derive(SmartPointer): require pointee to be maybe sized)

r? `@ghost`
`@rustbot` modify labels: rollup
This commit is contained in:
bors 2024-08-01 00:03:28 +00:00
commit 71b2116096
26 changed files with 490 additions and 214 deletions
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50
compiler/rustc_builtin_macros/src/deriving/smart_ptr.rs
View File

@ -1,5 +1,3 @@
use std::mem::swap;
use ast::ptr::P;
use ast::HasAttrs;
use rustc_ast::mut_visit::MutVisitor;
@ -154,13 +152,28 @@ pub fn expand_deriving_smart_ptr(
{
let pointee = &mut impl_generics.params[pointee_param_idx];
self_bounds = pointee.bounds.clone();
if !contains_maybe_sized_bound(&self_bounds)
&& !contains_maybe_sized_bound_on_pointee(
&generics.where_clause.predicates,
pointee_ty_ident.name,
)
{
cx.dcx()
.struct_span_err(
pointee_ty_ident.span,
format!(
"`derive(SmartPointer)` requires {} to be marked `?Sized`",
pointee_ty_ident.name
),
)
.emit();
return;
}
let arg = GenericArg::Type(s_ty.clone());
let unsize = cx.path_all(span, true, path!(span, core::marker::Unsize), vec![arg]);
pointee.bounds.push(cx.trait_bound(unsize, false));
let mut attrs = thin_vec![];
swap(&mut pointee.attrs, &mut attrs);
// Drop `#[pointee]` attribute since it should not be recognized outside `derive(SmartPointer)`
pointee.attrs = attrs.into_iter().filter(|attr| !attr.has_name(sym::pointee)).collect();
pointee.attrs.retain(|attr| !attr.has_name(sym::pointee));
}
// # Rewrite generic parameter bounds
@ -169,14 +182,14 @@ pub fn expand_deriving_smart_ptr(
// ```
// struct<
// U: Trait<T>,
// #[pointee] T: Trait<T>,
// #[pointee] T: Trait<T> + ?Sized,
// V: Trait<T>> ...
// ```
// ... generates this `impl` generic parameters
// ```
// impl<
// U: Trait<T> + Trait<__S>,
// T: Trait<T> + Unsize<__S>, // (**)
// T: Trait<T> + ?Sized + Unsize<__S>, // (**)
// __S: Trait<__S> + ?Sized, // (*)
// V: Trait<T> + Trait<__S>> ...
// ```
@ -218,23 +231,6 @@ pub fn expand_deriving_smart_ptr(
//
// We now insert `__S` with the missing bounds marked with (*) above.
// We should also write the bounds from `#[pointee]` to `__S` as required by `Unsize<__S>`.
let sized = cx.path_global(span, path!(span, core::marker::Sized));
// For some reason, we are not allowed to write `?Sized` bound twice like `__S: ?Sized + ?Sized`.
if !contains_maybe_sized_bound(&self_bounds)
&& !contains_maybe_sized_bound_on_pointee(
&generics.where_clause.predicates,
pointee_ty_ident.name,
)
{
self_bounds.push(GenericBound::Trait(
cx.poly_trait_ref(span, sized),
TraitBoundModifiers {
polarity: ast::BoundPolarity::Maybe(span),
constness: ast::BoundConstness::Never,
asyncness: ast::BoundAsyncness::Normal,
},
));
}
{
let mut substitution =
TypeSubstitution { from_name: pointee_ty_ident.name, to_ty: &s_ty, rewritten: false };
@ -252,7 +248,7 @@ pub fn expand_deriving_smart_ptr(
// where
// U: Trait<V> + Trait<T>,
// Companion<T>: Trait<T>,
// T: Trait<T>,
// T: Trait<T> + ?Sized,
// { .. }
// ```
// ... will have a impl prelude like so
@ -263,8 +259,8 @@ pub fn expand_deriving_smart_ptr(
// U: Trait<__S>,
// Companion<T>: Trait<T>,
// Companion<__S>: Trait<__S>,
// T: Trait<T>,
// __S: Trait<__S>,
// T: Trait<T> + ?Sized,
// __S: Trait<__S> + ?Sized,
// ```
//
// We should also write a few new `where` bounds from `#[pointee] T` to `__S`

2
compiler/rustc_hir_typeck/src/expr.rs
View File

@ -1306,6 +1306,8 @@ fn check_expr_loop(
// No way to know whether it's diverging because
// of a `break` or an outer `break` or `return`.
self.diverges.set(Diverges::Maybe);
} else {
self.diverges.set(self.diverges.get() | Diverges::always(expr.span));
}
// If we permit break with a value, then result type is

30
compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
View File

@ -48,16 +48,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
/// Produces warning on the given node, if the current point in the
/// function is unreachable, and there hasn't been another warning.
pub(crate) fn warn_if_unreachable(&self, id: HirId, span: Span, kind: &str) {
// FIXME: Combine these two 'if' expressions into one once
// let chains are implemented
if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() {
// If span arose from a desugaring of `if` or `while`, then it is the condition itself,
// which diverges, that we are about to lint on. This gives suboptimal diagnostics.
// Instead, stop here so that the `if`- or `while`-expression's block is linted instead.
if !span.is_desugaring(DesugaringKind::CondTemporary)
&& !span.is_desugaring(DesugaringKind::Async)
&& !orig_span.is_desugaring(DesugaringKind::Await)
{
if span.is_desugaring(DesugaringKind::CondTemporary) {
return;
}
// Don't lint if the result of an async block or async function is `!`.
// This does not affect the unreachable lints *within* the body.
if span.is_desugaring(DesugaringKind::Async) {
return;
}
// Don't lint *within* the `.await` operator, since that's all just desugaring junk.
// We only want to lint if there is a subsequent expression after the `.await`.
if span.is_desugaring(DesugaringKind::Await) {
return;
}
let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() else {
return;
};
// Don't warn twice.
self.diverges.set(Diverges::WarnedAlways);
debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind);
@ -71,8 +85,6 @@ pub(crate) fn warn_if_unreachable(&self, id: HirId, span: Span, kind: &str) {
);
})
}
}
}
/// Resolves type and const variables in `ty` if possible. Unlike the infcx
/// version (resolve_vars_if_possible), this version will

3
compiler/rustc_lint/src/precedence.rs
View File

@ -16,6 +16,7 @@
/// ### Example
///
/// ```rust,compile_fail
/// # #![deny(ambiguous_negative_literals)]
/// # #![allow(unused)]
/// -1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1
/// ```
@ -27,7 +28,7 @@
/// Method calls take precedence over unary precedence. Setting the
/// precedence explicitly makes the code clearer and avoid potential bugs.
pub AMBIGUOUS_NEGATIVE_LITERALS,
Deny,
Allow,
"ambiguous negative literals operations",
report_in_external_macro
}

8
compiler/rustc_target/src/spec/targets/loongarch64_unknown_linux_musl.rs
View File

@ -4,10 +4,10 @@ pub fn target() -> Target {
Target {
llvm_target: "loongarch64-unknown-linux-musl".into(),
metadata: crate::spec::TargetMetadata {
description: Some("LoongArch64 Linux (LP64D ABI) with musl 1.2.3".into()),
tier: Some(3),
host_tools: Some(false),
std: None, // ?
description: Some("LoongArch64 Linux (LP64D ABI) with musl 1.2.5".into()),
tier: Some(2),
host_tools: Some(true),
std: Some(true),
},
pointer_width: 64,
data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),

2
compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs
View File

@ -6,7 +6,7 @@ pub fn target() -> Target {
Target {
llvm_target: "loongarch64-unknown-none".into(),
metadata: crate::spec::TargetMetadata {
description: None,
description: Some("Freestanding/bare-metal LoongArch64".into()),
tier: Some(2),
host_tools: Some(false),
std: Some(false),

2
compiler/rustc_target/src/spec/targets/loongarch64_unknown_none_softfloat.rs
View File

@ -6,7 +6,7 @@ pub fn target() -> Target {
Target {
llvm_target: "loongarch64-unknown-none".into(),
metadata: crate::spec::TargetMetadata {
description: None,
description: Some("Freestanding/bare-metal LoongArch64 softfloat".into()),
tier: Some(2),
host_tools: Some(false),
std: Some(false),

1
library/std/src/sys/anonymous_pipe/tests.rs → library/std/src/pipe/tests.rs
View File

@ -2,6 +2,7 @@
use crate::pipe::pipe;
#[test]
#[cfg(all(windows, unix, not(miri)))]
fn pipe_creation_clone_and_rw() {
let (rx, tx) = pipe().unwrap();

41
library/std/src/sync/once.rs
View File

@ -264,6 +264,47 @@ pub fn is_completed(&self) -> bool {
self.inner.is_completed()
}
/// Blocks the current thread until initialization has completed.
///
/// # Example
///
/// ```rust
/// #![feature(once_wait)]
///
/// use std::sync::Once;
/// use std::thread;
///
/// static READY: Once = Once::new();
///
/// let thread = thread::spawn(|| {
/// READY.wait();
/// println!("everything is ready");
/// });
///
/// READY.call_once(|| println!("performing setup"));
/// ```
///
/// # Panics
///
/// If this [`Once`] has been poisoned because an initialization closure has
/// panicked, this method will also panic. Use [`wait_force`](Self::wait_force)
/// if this behaviour is not desired.
#[unstable(feature = "once_wait", issue = "127527")]
pub fn wait(&self) {
if !self.inner.is_completed() {
self.inner.wait(false);
}
}
/// Blocks the current thread until initialization has completed, ignoring
/// poisoning.
#[unstable(feature = "once_wait", issue = "127527")]
pub fn wait_force(&self) {
if !self.inner.is_completed() {
self.inner.wait(true);
}
}
/// Returns the current state of the `Once` instance.
///
/// Since this takes a mutable reference, no initialization can currently

47
library/std/src/sync/once/tests.rs
View File

@ -1,5 +1,8 @@
use super::Once;
use crate::sync::atomic::AtomicBool;
use crate::sync::atomic::Ordering::Relaxed;
use crate::sync::mpsc::channel;
use crate::time::Duration;
use crate::{panic, thread};
#[test]
@ -113,3 +116,47 @@ fn wait_for_force_to_finish() {
assert!(t1.join().is_ok());
assert!(t2.join().is_ok());
}
#[test]
fn wait() {
for _ in 0..50 {
let val = AtomicBool::new(false);
let once = Once::new();
thread::scope(|s| {
for _ in 0..4 {
s.spawn(|| {
once.wait();
assert!(val.load(Relaxed));
});
}
once.call_once(|| val.store(true, Relaxed));
});
}
}
#[test]
fn wait_on_poisoned() {
let once = Once::new();
panic::catch_unwind(|| once.call_once(|| panic!())).unwrap_err();
panic::catch_unwind(|| once.wait()).unwrap_err();
}
#[test]
fn wait_force_on_poisoned() {
let once = Once::new();
thread::scope(|s| {
panic::catch_unwind(|| once.call_once(|| panic!())).unwrap_err();
s.spawn(|| {
thread::sleep(Duration::from_millis(100));
once.call_once_force(|_| {});
});
once.wait_force();
})
}

28
library/std/src/sync/once_lock.rs
View File

@ -167,6 +167,34 @@ pub fn get_mut(&mut self) -> Option<&mut T> {
}
}
/// Blocks the current thread until the cell is initialized.
///
/// # Example
///
/// Waiting for a computation on another thread to finish:
/// ```rust
/// #![feature(once_wait)]
///
/// use std::thread;
/// use std::sync::OnceLock;
///
/// let value = OnceLock::new();
///
/// thread::scope(|s| {
/// s.spawn(|| value.set(1 + 1));
///
/// let result = value.wait();
/// assert_eq!(result, &2);
/// })
/// ```
#[inline]
#[unstable(feature = "once_wait", issue = "127527")]
pub fn wait(&self) -> &T {
self.once.wait_force();
unsafe { self.get_unchecked() }
}
/// Sets the contents of this cell to `value`.
///
/// May block if another thread is currently attempting to initialize the cell. The cell is

14
library/std/src/sys/anonymous_pipe/mod.rs
View File

@ -1,18 +1,14 @@
#![forbid(unsafe_op_in_unsafe_fn)]
cfg_if::cfg_if! {
if #[cfg(unix)] {
mod unix;
pub(crate) use unix::{AnonPipe, pipe};
#[cfg(all(test, not(miri)))]
mod tests;
pub use unix::{AnonPipe, pipe};
} else if #[cfg(windows)] {
mod windows;
pub(crate) use windows::{AnonPipe, pipe};
#[cfg(all(test, not(miri)))]
mod tests;
pub use windows::{AnonPipe, pipe};
} else {
mod unsupported;
pub(crate) use unsupported::{AnonPipe, pipe};
pub use unsupported::{AnonPipe, pipe};
}
}

8
library/std/src/sys/anonymous_pipe/unix.rs
View File

@ -6,10 +6,10 @@
use crate::sys::pipe::anon_pipe;
use crate::sys_common::{FromInner, IntoInner};
pub(crate) type AnonPipe = FileDesc;
pub type AnonPipe = FileDesc;
#[inline]
pub(crate) fn pipe() -> io::Result<(AnonPipe, AnonPipe)> {
pub fn pipe() -> io::Result<(AnonPipe, AnonPipe)> {
anon_pipe().map(|(rx, wx)| (rx.into_inner(), wx.into_inner()))
}
@ -34,7 +34,7 @@ fn from(pipe: PipeReader) -> Self {
#[unstable(feature = "anonymous_pipe", issue = "127154")]
impl FromRawFd for PipeReader {
unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
Self(FileDesc::from_raw_fd(raw_fd))
unsafe { Self(FileDesc::from_raw_fd(raw_fd)) }
}
}
#[unstable(feature = "anonymous_pipe", issue = "127154")]
@ -71,7 +71,7 @@ fn from(pipe: PipeWriter) -> Self {
#[unstable(feature = "anonymous_pipe", issue = "127154")]
impl FromRawFd for PipeWriter {
unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
Self(FileDesc::from_raw_fd(raw_fd))
unsafe { Self(FileDesc::from_raw_fd(raw_fd)) }
}
}
#[unstable(feature = "anonymous_pipe", issue = "127154")]

4
library/std/src/sys/anonymous_pipe/unsupported.rs
View File

@ -1,10 +1,10 @@
use crate::io;
use crate::pipe::{PipeReader, PipeWriter};
use crate::process::Stdio;
pub(crate) use crate::sys::pipe::AnonPipe;
pub use crate::sys::pipe::AnonPipe;
#[inline]
pub(crate) fn pipe() -> io::Result<(AnonPipe, AnonPipe)> {
pub fn pipe() -> io::Result<(AnonPipe, AnonPipe)> {
Err(io::Error::UNSUPPORTED_PLATFORM)
}

24
library/std/src/sys/anonymous_pipe/windows.rs
View File

@ -1,18 +1,26 @@
use crate::io;
use crate::os::windows::io::{
AsHandle, AsRawHandle, BorrowedHandle, FromRawHandle, IntoRawHandle, OwnedHandle, RawHandle,
};
use crate::pipe::{PipeReader, PipeWriter};
use crate::process::Stdio;
use crate::sys::c;
use crate::sys::handle::Handle;
use crate::sys::pipe::unnamed_anon_pipe;
use crate::sys_common::{FromInner, IntoInner};
use crate::{io, ptr};
pub(crate) type AnonPipe = Handle;
pub type AnonPipe = Handle;
#[inline]
pub(crate) fn pipe() -> io::Result<(AnonPipe, AnonPipe)> {
unnamed_anon_pipe().map(|(rx, wx)| (rx.into_inner(), wx.into_inner()))
pub fn pipe() -> io::Result<(AnonPipe, AnonPipe)> {
let mut read_pipe = c::INVALID_HANDLE_VALUE;
let mut write_pipe = c::INVALID_HANDLE_VALUE;
let ret = unsafe { c::CreatePipe(&mut read_pipe, &mut write_pipe, ptr::null_mut(), 0) };
if ret == 0 {
Err(io::Error::last_os_error())
} else {
unsafe { Ok((Handle::from_raw_handle(read_pipe), Handle::from_raw_handle(write_pipe))) }
}
}
#[unstable(feature = "anonymous_pipe", issue = "127154")]
@ -31,7 +39,7 @@ fn as_raw_handle(&self) -> RawHandle {
#[unstable(feature = "anonymous_pipe", issue = "127154")]
impl FromRawHandle for PipeReader {
unsafe fn from_raw_handle(raw_handle: RawHandle) -> Self {
Self(Handle::from_raw_handle(raw_handle))
unsafe { Self(Handle::from_raw_handle(raw_handle)) }
}
}
#[unstable(feature = "anonymous_pipe", issue = "127154")]
@ -70,7 +78,7 @@ fn as_raw_handle(&self) -> RawHandle {
#[unstable(feature = "anonymous_pipe", issue = "127154")]
impl FromRawHandle for PipeWriter {
unsafe fn from_raw_handle(raw_handle: RawHandle) -> Self {
Self(Handle::from_raw_handle(raw_handle))
unsafe { Self(Handle::from_raw_handle(raw_handle)) }
}
}
#[unstable(feature = "anonymous_pipe", issue = "127154")]

1
library/std/src/sys/mod.rs
View File

@ -7,7 +7,6 @@
mod personality;
#[unstable(feature = "anonymous_pipe", issue = "127154")]
pub mod anonymous_pipe;
pub mod backtrace;
pub mod cmath;

17
library/std/src/sys/pal/windows/pipe.rs
View File

@ -36,23 +36,6 @@ pub struct Pipes {
pub theirs: AnonPipe,
}
/// Create true unnamed anonymous pipe.
pub fn unnamed_anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
let mut read_pipe = c::INVALID_HANDLE_VALUE;
let mut write_pipe = c::INVALID_HANDLE_VALUE;
let ret = unsafe { c::CreatePipe(&mut read_pipe, &mut write_pipe, ptr::null_mut(), 0) };
if ret == 0 {
Err(io::Error::last_os_error())
} else {
Ok((
AnonPipe::from_inner(unsafe { Handle::from_raw_handle(read_pipe) }),
AnonPipe::from_inner(unsafe { Handle::from_raw_handle(write_pipe) }),
))
}
}
/// Although this looks similar to `anon_pipe` in the Unix module it's actually
/// subtly different. Here we'll return two pipes in the `Pipes` return value,
/// but one is intended for "us" where as the other is intended for "someone

124
library/std/src/sys/sync/once/futex.rs
View File

@ -6,7 +6,7 @@
use crate::sys::futex::{futex_wait, futex_wake_all};
// On some platforms, the OS is very nice and handles the waiter queue for us.
// This means we only need one atomic value with 5 states:
// This means we only need one atomic value with 4 states:
/// No initialization has run yet, and no thread is currently using the Once.
const INCOMPLETE: u32 = 0;
@ -17,16 +17,20 @@
/// Some thread is currently attempting to run initialization. It may succeed,
/// so all future threads need to wait for it to finish.
const RUNNING: u32 = 2;
/// Some thread is currently attempting to run initialization and there are threads
/// waiting for it to finish.
const QUEUED: u32 = 3;
/// Initialization has completed and all future calls should finish immediately.
const COMPLETE: u32 = 4;
const COMPLETE: u32 = 3;
// Threads wait by setting the state to QUEUED and calling `futex_wait` on the state
// An additional bit indicates whether there are waiting threads:
/// May only be set if the state is not COMPLETE.
const QUEUED: u32 = 4;
// Threads wait by setting the QUEUED bit and calling `futex_wait` on the state
// variable. When the running thread finishes, it will wake all waiting threads using
// `futex_wake_all`.
const STATE_MASK: u32 = 0b11;
pub struct OnceState {
poisoned: bool,
set_state_to: Cell<u32>,
@ -45,7 +49,7 @@ pub fn poison(&self) {
}
struct CompletionGuard<'a> {
state: &'a AtomicU32,
state_and_queued: &'a AtomicU32,
set_state_on_drop_to: u32,
}
@ -54,32 +58,32 @@ fn drop(&mut self) {
// Use release ordering to propagate changes to all threads checking
// up on the Once. `futex_wake_all` does its own synchronization, hence
// we do not need `AcqRel`.
if self.state.swap(self.set_state_on_drop_to, Release) == QUEUED {
futex_wake_all(self.state);
if self.state_and_queued.swap(self.set_state_on_drop_to, Release) & QUEUED != 0 {
futex_wake_all(self.state_and_queued);
}
}
}
pub struct Once {
state: AtomicU32,
state_and_queued: AtomicU32,
}
impl Once {
#[inline]
pub const fn new() -> Once {
Once { state: AtomicU32::new(INCOMPLETE) }
Once { state_and_queued: AtomicU32::new(INCOMPLETE) }
}
#[inline]
pub fn is_completed(&self) -> bool {
// Use acquire ordering to make all initialization changes visible to the
// current thread.
self.state.load(Acquire) == COMPLETE
self.state_and_queued.load(Acquire) == COMPLETE
}
#[inline]
pub(crate) fn state(&mut self) -> ExclusiveState {
match *self.state.get_mut() {
match *self.state_and_queued.get_mut() {
INCOMPLETE => ExclusiveState::Incomplete,
POISONED => ExclusiveState::Poisoned,
COMPLETE => ExclusiveState::Complete,
@ -87,31 +91,73 @@ pub(crate) fn state(&mut self) -> ExclusiveState {
}
}
// This uses FnMut to match the API of the generic implementation. As this
// implementation is quite light-weight, it is generic over the closure and
// so avoids the cost of dynamic dispatch.
#[cold]
#[track_caller]
pub fn call(&self, ignore_poisoning: bool, f: &mut impl FnMut(&public::OnceState)) {
let mut state = self.state.load(Acquire);
pub fn wait(&self, ignore_poisoning: bool) {
let mut state_and_queued = self.state_and_queued.load(Acquire);
loop {
let state = state_and_queued & STATE_MASK;
let queued = state_and_queued & QUEUED != 0;
match state {
COMPLETE => return,
POISONED if !ignore_poisoning => {
// Panic to propagate the poison.
panic!("Once instance has previously been poisoned");
}
_ => {
// Set the QUEUED bit if it has not already been set.
if !queued {
state_and_queued += QUEUED;
if let Err(new) = self.state_and_queued.compare_exchange_weak(
state,
state_and_queued,
Relaxed,
Acquire,
) {
state_and_queued = new;
continue;
}
}
futex_wait(&self.state_and_queued, state_and_queued, None);
state_and_queued = self.state_and_queued.load(Acquire);
}
}
}
}
#[cold]
#[track_caller]
pub fn call(&self, ignore_poisoning: bool, f: &mut dyn FnMut(&public::OnceState)) {
let mut state_and_queued = self.state_and_queued.load(Acquire);
loop {
let state = state_and_queued & STATE_MASK;
let queued = state_and_queued & QUEUED != 0;
match state {
COMPLETE => return,
POISONED if !ignore_poisoning => {
// Panic to propagate the poison.
panic!("Once instance has previously been poisoned");
}
INCOMPLETE | POISONED => {
// Try to register the current thread as the one running.
if let Err(new) =
self.state.compare_exchange_weak(state, RUNNING, Acquire, Acquire)
{
state = new;
let next = RUNNING + if queued { QUEUED } else { 0 };
if let Err(new) = self.state_and_queued.compare_exchange_weak(
state_and_queued,
next,
Acquire,
Acquire,
) {
state_and_queued = new;
continue;
}
// `waiter_queue` will manage other waiting threads, and
// wake them up on drop.
let mut waiter_queue =
CompletionGuard { state: &self.state, set_state_on_drop_to: POISONED };
let mut waiter_queue = CompletionGuard {
state_and_queued: &self.state_and_queued,
set_state_on_drop_to: POISONED,
};
// Run the function, letting it know if we're poisoned or not.
let f_state = public::OnceState {
inner: OnceState {
@ -123,21 +169,27 @@ pub fn call(&self, ignore_poisoning: bool, f: &mut impl FnMut(&public::OnceState
waiter_queue.set_state_on_drop_to = f_state.inner.set_state_to.get();
return;
}
RUNNING | QUEUED => {
// Set the state to QUEUED if it is not already.
if state == RUNNING
&& let Err(new) =
self.state.compare_exchange_weak(RUNNING, QUEUED, Relaxed, Acquire)
{
state = new;
_ => {
// All other values must be RUNNING.
assert!(state == RUNNING);
// Set the QUEUED bit if it is not already set.
if !queued {
state_and_queued += QUEUED;
if let Err(new) = self.state_and_queued.compare_exchange_weak(
state,
state_and_queued,
Relaxed,
Acquire,
) {
state_and_queued = new;
continue;
}
}
futex_wait(&self.state, QUEUED, None);
state = self.state.load(Acquire);
}
COMPLETE => return,
_ => unreachable!("state is never set to invalid values"),
futex_wait(&self.state_and_queued, state_and_queued, None);
state_and_queued = self.state_and_queued.load(Acquire);
}
}
}
}

6
library/std/src/sys/sync/once/no_threads.rs
View File

@ -55,6 +55,12 @@ pub(crate) fn state(&mut self) -> ExclusiveState {
}
}
#[cold]
#[track_caller]
pub fn wait(&self, _ignore_poisoning: bool) {
panic!("not implementable on this target");
}
#[cold]
#[track_caller]
pub fn call(&self, ignore_poisoning: bool, f: &mut impl FnMut(&public::OnceState)) {

146
library/std/src/sys/sync/once/queue.rs
View File

@ -56,20 +56,21 @@
// allowed, so no need for `SeqCst`.
use crate::cell::Cell;
use crate::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
use crate::sync::atomic::Ordering::{AcqRel, Acquire, Release};
use crate::sync::atomic::{AtomicBool, AtomicPtr};
use crate::sync::once::ExclusiveState;
use crate::thread::{self, Thread};
use crate::{fmt, ptr, sync as public};
type Masked = ();
type StateAndQueue = *mut ();
pub struct Once {
state_and_queue: AtomicPtr<Masked>,
state_and_queue: AtomicPtr<()>,
}
pub struct OnceState {
poisoned: bool,
set_state_on_drop_to: Cell<*mut Masked>,
set_state_on_drop_to: Cell<StateAndQueue>,
}
// Four states that a Once can be in, encoded into the lower bits of
@ -81,7 +82,8 @@ pub struct OnceState {
// Mask to learn about the state. All other bits are the queue of waiters if
// this is in the RUNNING state.
const STATE_MASK: usize = 0x3;
const STATE_MASK: usize = 0b11;
const QUEUE_MASK: usize = !STATE_MASK;
// Representation of a node in the linked list of waiters, used while in the
// RUNNING state.
@ -93,15 +95,23 @@ pub struct OnceState {
struct Waiter {
thread: Cell<Option<Thread>>,
signaled: AtomicBool,
next: *const Waiter,
next: Cell<*const Waiter>,
}
// Head of a linked list of waiters.
// Every node is a struct on the stack of a waiting thread.
// Will wake up the waiters when it gets dropped, i.e. also on panic.
struct WaiterQueue<'a> {
state_and_queue: &'a AtomicPtr<Masked>,
set_state_on_drop_to: *mut Masked,
state_and_queue: &'a AtomicPtr<()>,
set_state_on_drop_to: StateAndQueue,
}
fn to_queue(current: StateAndQueue) -> *const Waiter {
current.mask(QUEUE_MASK).cast()
}
fn to_state(current: StateAndQueue) -> usize {
current.addr() & STATE_MASK
}
impl Once {
@ -117,7 +127,7 @@ pub fn is_completed(&self) -> bool {
// operations visible to us, and, this being a fast path, weaker
// ordering helps with performance. This `Acquire` synchronizes with
// `Release` operations on the slow path.
self.state_and_queue.load(Ordering::Acquire).addr() == COMPLETE
self.state_and_queue.load(Acquire).addr() == COMPLETE
}
#[inline]
@ -130,6 +140,25 @@ pub(crate) fn state(&mut self) -> ExclusiveState {
}
}
#[cold]
#[track_caller]
pub fn wait(&self, ignore_poisoning: bool) {
let mut current = self.state_and_queue.load(Acquire);
loop {
let state = to_state(current);
match state {
COMPLETE => return,
POISONED if !ignore_poisoning => {
// Panic to propagate the poison.
panic!("Once instance has previously been poisoned");
}
_ => {
current = wait(&self.state_and_queue, current, !ignore_poisoning);
}
}
}
}
// This is a non-generic function to reduce the monomorphization cost of
// using `call_once` (this isn't exactly a trivial or small implementation).
//
@ -144,9 +173,10 @@ pub(crate) fn state(&mut self) -> ExclusiveState {
#[cold]
#[track_caller]
pub fn call(&self, ignore_poisoning: bool, init: &mut dyn FnMut(&public::OnceState)) {
let mut state_and_queue = self.state_and_queue.load(Ordering::Acquire);
let mut current = self.state_and_queue.load(Acquire);
loop {
match state_and_queue.addr() {
let state = to_state(current);
match state {
COMPLETE => break,
POISONED if !ignore_poisoning => {
// Panic to propagate the poison.
@ -154,16 +184,16 @@ pub fn call(&self, ignore_poisoning: bool, init: &mut dyn FnMut(&public::OnceSta
}
POISONED | INCOMPLETE => {
// Try to register this thread as the one RUNNING.
let exchange_result = self.state_and_queue.compare_exchange(
state_and_queue,
ptr::without_provenance_mut(RUNNING),
Ordering::Acquire,
Ordering::Acquire,
);
if let Err(old) = exchange_result {
state_and_queue = old;
if let Err(new) = self.state_and_queue.compare_exchange_weak(
current,
current.mask(QUEUE_MASK).wrapping_byte_add(RUNNING),
Acquire,
Acquire,
) {
current = new;
continue;
}
// `waiter_queue` will manage other waiting threads, and
// wake them up on drop.
let mut waiter_queue = WaiterQueue {
@ -174,54 +204,57 @@ pub fn call(&self, ignore_poisoning: bool, init: &mut dyn FnMut(&public::OnceSta
// poisoned or not.
let init_state = public::OnceState {
inner: OnceState {
poisoned: state_and_queue.addr() == POISONED,
poisoned: state == POISONED,
set_state_on_drop_to: Cell::new(ptr::without_provenance_mut(COMPLETE)),
},
};
init(&init_state);
waiter_queue.set_state_on_drop_to = init_state.inner.set_state_on_drop_to.get();
break;
return;
}
_ => {
// All other values must be RUNNING with possibly a
// pointer to the waiter queue in the more significant bits.
assert!(state_and_queue.addr() & STATE_MASK == RUNNING);
wait(&self.state_and_queue, state_and_queue);
state_and_queue = self.state_and_queue.load(Ordering::Acquire);
assert!(state == RUNNING);
current = wait(&self.state_and_queue, current, true);
}
}
}
}
}
fn wait(state_and_queue: &AtomicPtr<Masked>, mut current_state: *mut Masked) {
// Note: the following code was carefully written to avoid creating a
// mutable reference to `node` that gets aliased.
loop {
// Don't queue this thread if the status is no longer running,
// otherwise we will not be woken up.
if current_state.addr() & STATE_MASK != RUNNING {
return;
}
// Create the node for our current thread.
let node = Waiter {
fn wait(
state_and_queue: &AtomicPtr<()>,
mut current: StateAndQueue,
return_on_poisoned: bool,
) -> StateAndQueue {
let node = &Waiter {
thread: Cell::new(Some(thread::current())),
signaled: AtomicBool::new(false),
next: current_state.with_addr(current_state.addr() & !STATE_MASK) as *const Waiter,
next: Cell::new(ptr::null()),
};
let me = core::ptr::addr_of!(node) as *const Masked as *mut Masked;
loop {
let state = to_state(current);
let queue = to_queue(current);
// If initialization has finished, return.
if state == COMPLETE || (return_on_poisoned && state == POISONED) {
return current;
}
// Update the node for our current thread.
node.next.set(queue);
// Try to slide in the node at the head of the linked list, making sure
// that another thread didn't just replace the head of the linked list.
let exchange_result = state_and_queue.compare_exchange(
current_state,
me.with_addr(me.addr() | RUNNING),
Ordering::Release,
Ordering::Relaxed,
);
if let Err(old) = exchange_result {
current_state = old;
if let Err(new) = state_and_queue.compare_exchange_weak(
current,
ptr::from_ref(node).wrapping_byte_add(state) as StateAndQueue,
Release,
Acquire,
) {
current = new;
continue;
}
@ -230,14 +263,15 @@ fn wait(state_and_queue: &AtomicPtr<Masked>, mut current_state: *mut Masked) {
// would drop our `Waiter` node and leave a hole in the linked list
// (and a dangling reference). Guard against spurious wakeups by
// reparking ourselves until we are signaled.
while !node.signaled.load(Ordering::Acquire) {
while !node.signaled.load(Acquire) {
// If the managing thread happens to signal and unpark us before we
// can park ourselves, the result could be this thread never gets
// unparked. Luckily `park` comes with the guarantee that if it got
// an `unpark` just before on an unparked thread it does not park.
thread::park();
}
break;
return state_and_queue.load(Acquire);
}
}
@ -251,11 +285,10 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
impl Drop for WaiterQueue<'_> {
fn drop(&mut self) {
// Swap out our state with however we finished.
let state_and_queue =
self.state_and_queue.swap(self.set_state_on_drop_to, Ordering::AcqRel);
let current = self.state_and_queue.swap(self.set_state_on_drop_to, AcqRel);
// We should only ever see an old state which was RUNNING.
assert_eq!(state_and_queue.addr() & STATE_MASK, RUNNING);
assert_eq!(current.addr() & STATE_MASK, RUNNING);
// Walk the entire linked list of waiters and wake them up (in lifo
// order, last to register is first to wake up).
@ -264,16 +297,13 @@ fn drop(&mut self) {
// free `node` if there happens to be has a spurious wakeup.
// So we have to take out the `thread` field and copy the pointer to
// `next` first.
let mut queue =
state_and_queue.with_addr(state_and_queue.addr() & !STATE_MASK) as *const Waiter;
let mut queue = to_queue(current);
while !queue.is_null() {
let next = (*queue).next;
let next = (*queue).next.get();
let thread = (*queue).thread.take().unwrap();
(*queue).signaled.store(true, Ordering::Release);
// ^- FIXME (maybe): This is another case of issue #55005
// `store()` has a potentially dangling ref to `signaled`.
queue = next;
(*queue).signaled.store(true, Release);
thread.unpark();
queue = next;
}
}
}

15
tests/ui/async-await/unreachable-lint-2.rs Normal file
View File

@ -0,0 +1,15 @@
//@ edition:2018
#![deny(unreachable_code)]
async fn foo() {
endless().await;
println!("this is unreachable!");
//~^ ERROR unreachable statement
}
async fn endless() -> ! {
loop {}
}
fn main() { }

17
tests/ui/async-await/unreachable-lint-2.stderr Normal file
View File

@ -0,0 +1,17 @@
error: unreachable statement
--> $DIR/unreachable-lint-2.rs:7:5
|
LL | endless().await;
| ----- any code following this expression is unreachable
LL | println!("this is unreachable!");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
|
note: the lint level is defined here
--> $DIR/unreachable-lint-2.rs:3:9
|
LL | #![deny(unreachable_code)]
| ^^^^^^^^^^^^^^^^
= note: this error originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error

30
tests/ui/deriving/deriving-smart-pointer-neg.rs
View File

@ -1,5 +1,6 @@
#![feature(derive_smart_pointer, arbitrary_self_types)]
extern crate core;
use std::marker::SmartPointer;
#[derive(SmartPointer)]
@ -35,6 +36,13 @@ struct NotTransparent<'a, #[pointee] T: ?Sized> {
ptr: &'a T,
}
#[derive(SmartPointer)]
#[repr(transparent)]
struct NoMaybeSized<'a, #[pointee] T> {
//~^ ERROR: `derive(SmartPointer)` requires T to be marked `?Sized`
ptr: &'a T,
}
// However, reordering attributes should work nevertheless.
#[repr(transparent)]
#[derive(SmartPointer)]
@ -42,4 +50,26 @@ struct ThisIsAPossibleSmartPointer<'a, #[pointee] T: ?Sized> {
ptr: &'a T,
}
// Also, these paths to Sized should work
#[derive(SmartPointer)]
#[repr(transparent)]
struct StdSized<'a, #[pointee] T: ?std::marker::Sized> {
ptr: &'a T,
}
#[derive(SmartPointer)]
#[repr(transparent)]
struct CoreSized<'a, #[pointee] T: ?core::marker::Sized> {
ptr: &'a T,
}
#[derive(SmartPointer)]
#[repr(transparent)]
struct GlobalStdSized<'a, #[pointee] T: ?::std::marker::Sized> {
ptr: &'a T,
}
#[derive(SmartPointer)]
#[repr(transparent)]
struct GlobalCoreSized<'a, #[pointee] T: ?::core::marker::Sized> {
ptr: &'a T,
}
fn main() {}

26
tests/ui/deriving/deriving-smart-pointer-neg.stderr
View File

@ -1,5 +1,5 @@
error: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
--> $DIR/deriving-smart-pointer-neg.rs:5:10
--> $DIR/deriving-smart-pointer-neg.rs:6:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
@ -7,7 +7,7 @@ LL | #[derive(SmartPointer)]
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: At least one generic type should be designated as `#[pointee]` in order to derive `SmartPointer` traits
--> $DIR/deriving-smart-pointer-neg.rs:11:10
--> $DIR/deriving-smart-pointer-neg.rs:12:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
@ -15,7 +15,7 @@ LL | #[derive(SmartPointer)]
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: `SmartPointer` can only be derived on `struct`s with at least one field
--> $DIR/deriving-smart-pointer-neg.rs:18:10
--> $DIR/deriving-smart-pointer-neg.rs:19:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
@ -23,7 +23,7 @@ LL | #[derive(SmartPointer)]
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: `SmartPointer` can only be derived on `struct`s with at least one field
--> $DIR/deriving-smart-pointer-neg.rs:25:10
--> $DIR/deriving-smart-pointer-neg.rs:26:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
@ -31,15 +31,21 @@ LL | #[derive(SmartPointer)]
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: `SmartPointer` can only be derived on `struct`s with `#[repr(transparent)]`
--> $DIR/deriving-smart-pointer-neg.rs:32:10
--> $DIR/deriving-smart-pointer-neg.rs:33:10
|
LL | #[derive(SmartPointer)]
| ^^^^^^^^^^^^
|
= note: this error originates in the derive macro `SmartPointer` (in Nightly builds, run with -Z macro-backtrace for more info)
error: `derive(SmartPointer)` requires T to be marked `?Sized`
--> $DIR/deriving-smart-pointer-neg.rs:41:36
|
LL | struct NoMaybeSized<'a, #[pointee] T> {
| ^
error[E0392]: lifetime parameter `'a` is never used
--> $DIR/deriving-smart-pointer-neg.rs:21:16
--> $DIR/deriving-smart-pointer-neg.rs:22:16
|
LL | struct NoField<'a, #[pointee] T: ?Sized> {}
| ^^ unused lifetime parameter
@ -47,7 +53,7 @@ LL | struct NoField<'a, #[pointee] T: ?Sized> {}
= help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`
error[E0392]: type parameter `T` is never used
--> $DIR/deriving-smart-pointer-neg.rs:21:31
--> $DIR/deriving-smart-pointer-neg.rs:22:31
|
LL | struct NoField<'a, #[pointee] T: ?Sized> {}
| ^ unused type parameter
@ -55,7 +61,7 @@ LL | struct NoField<'a, #[pointee] T: ?Sized> {}
= help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
error[E0392]: lifetime parameter `'a` is never used
--> $DIR/deriving-smart-pointer-neg.rs:28:20
--> $DIR/deriving-smart-pointer-neg.rs:29:20
|
LL | struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
| ^^ unused lifetime parameter
@ -63,13 +69,13 @@ LL | struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
= help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`
error[E0392]: type parameter `T` is never used
--> $DIR/deriving-smart-pointer-neg.rs:28:35
--> $DIR/deriving-smart-pointer-neg.rs:29:35
|
LL | struct NoFieldUnit<'a, #[pointee] T: ?Sized>();
| ^ unused type parameter
|
= help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
error: aborting due to 9 previous errors
error: aborting due to 10 previous errors
For more information about this error, try `rustc --explain E0392`.

2
tests/ui/lint/negative_literals.rs
View File

@ -1,5 +1,7 @@
//@ check-fail
#![deny(ambiguous_negative_literals)]
fn main() {
let _ = -1i32.abs();
//~^ ERROR `-` has lower precedence than method calls

28
tests/ui/lint/negative_literals.stderr
View File

@ -1,11 +1,15 @@
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:4:13
--> $DIR/negative_literals.rs:6:13
|
LL | let _ = -1i32.abs();
| ^^^^^^^^^^^
|
= note: e.g. `-4.abs()` equals `-4`; while `(-4).abs()` equals `4`
= note: `#[deny(ambiguous_negative_literals)]` on by default
note: the lint level is defined here
--> $DIR/negative_literals.rs:3:9
|
LL | #![deny(ambiguous_negative_literals)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: add parentheses around the `-` and the literal to call the method on a negative literal
|
LL | let _ = (-1i32).abs();
@ -16,7 +20,7 @@ LL | let _ = -(1i32.abs());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:6:13
--> $DIR/negative_literals.rs:8:13
|
LL | let _ = -1f32.abs();
| ^^^^^^^^^^^
@ -32,7 +36,7 @@ LL | let _ = -(1f32.abs());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:8:13
--> $DIR/negative_literals.rs:10:13
|
LL | let _ = -1f64.asin();
| ^^^^^^^^^^^^
@ -48,7 +52,7 @@ LL | let _ = -(1f64.asin());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:10:13
--> $DIR/negative_literals.rs:12:13
|
LL | let _ = -1f64.asinh();
| ^^^^^^^^^^^^^
@ -64,7 +68,7 @@ LL | let _ = -(1f64.asinh());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:12:13
--> $DIR/negative_literals.rs:14:13
|
LL | let _ = -1f64.tan();
| ^^^^^^^^^^^
@ -80,7 +84,7 @@ LL | let _ = -(1f64.tan());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:14:13
--> $DIR/negative_literals.rs:16:13
|
LL | let _ = -1f64.tanh();
| ^^^^^^^^^^^^
@ -96,7 +100,7 @@ LL | let _ = -(1f64.tanh());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:16:13
--> $DIR/negative_literals.rs:18:13
|
LL | let _ = -1.0_f64.cos().cos();
| ^^^^^^^^^^^^^^^^^^^^
@ -112,7 +116,7 @@ LL | let _ = -(1.0_f64.cos().cos());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:18:13
--> $DIR/negative_literals.rs:20:13
|
LL | let _ = -1.0_f64.cos().sin();
| ^^^^^^^^^^^^^^^^^^^^
@ -128,7 +132,7 @@ LL | let _ = -(1.0_f64.cos().sin());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:20:13
--> $DIR/negative_literals.rs:22:13
|
LL | let _ = -1.0_f64.sin().cos();
| ^^^^^^^^^^^^^^^^^^^^
@ -144,7 +148,7 @@ LL | let _ = -(1.0_f64.sin().cos());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:22:13
--> $DIR/negative_literals.rs:24:13
|
LL | let _ = -1f64.sin().sin();
| ^^^^^^^^^^^^^^^^^
@ -160,7 +164,7 @@ LL | let _ = -(1f64.sin().sin());
| + +
error: `-` has lower precedence than method calls, which might be unexpected
--> $DIR/negative_literals.rs:25:11
--> $DIR/negative_literals.rs:27:11
|
LL | dbg!( -1.0_f32.cos() );
| ^^^^^^^^^^^^^^