Merge from rustc

Author: The Miri Conjob Bot

core/src/primitive_docs.rs

@@ -1605,9 +1605,9 @@ mod prim_ref {}
 /// type in the function pointer to the type at the function declaration, and the return value is
 /// [`transmute`d][mem::transmute] from the type in the declaration to the type in the
 /// pointer. All the usual caveats and concerns around transmutation apply; for instance, if the
-/// function expects a `NonNullI32` and the function pointer uses the ABI-compatible type
-/// `Option<NonNullI32>`, and the value used for the argument is `None`, then this call is Undefined
-/// Behavior since transmuting `None::<NonNullI32>` to `NonNullI32` violates the non-null
+/// function expects a `NonZeroI32` and the function pointer uses the ABI-compatible type
+/// `Option<NonZeroI32>`, and the value used for the argument is `None`, then this call is Undefined
+/// Behavior since transmuting `None::<NonZeroI32>` to `NonZeroI32` violates the non-zero
 /// requirement.
 ///
 /// #### Requirements concerning target features

core/src/task/wake.rs

@@ -329,12 +329,14 @@ impl Waker {
         Waker { waker }
     }
 
-    /// Creates a new `Waker` that does nothing when `wake` is called.
+    /// Returns a reference to a `Waker` that does nothing when used.
     ///
     /// This is mostly useful for writing tests that need a [`Context`] to poll
     /// some futures, but are not expecting those futures to wake the waker or
     /// do not need to do anything specific if it happens.
     ///
+    /// If an owned `Waker` is needed, `clone()` this one.
+    ///
     /// # Examples
     ///
     /// ```
@@ -343,16 +345,20 @@ impl Waker {
     /// use std::future::Future;
     /// use std::task;
     ///
-    /// let waker = task::Waker::noop();
-    /// let mut cx = task::Context::from_waker(&waker);
+    /// let mut cx = task::Context::from_waker(task::Waker::noop());
     ///
     /// let mut future = Box::pin(async { 10 });
     /// assert_eq!(future.as_mut().poll(&mut cx), task::Poll::Ready(10));
     /// ```
     #[inline]
     #[must_use]
     #[unstable(feature = "noop_waker", issue = "98286")]
-    pub const fn noop() -> Waker {
+    pub const fn noop() -> &'static Waker {
+        // Ideally all this data would be explicitly `static` because it is used by reference and
+        // only ever needs one copy. But `const fn`s (and `const` items) cannot refer to statics,
+        // even though their values can be promoted to static. (That might change; see #119618.)
+        // An alternative would be a `pub static NOOP: &Waker`, but associated static items are not
+        // currently allowed either, and making it non-associated would be unergonomic.
         const VTABLE: RawWakerVTable = RawWakerVTable::new(
             // Cloning just returns a new no-op raw waker
             |_| RAW,
@@ -364,8 +370,9 @@ impl Waker {
             |_| {},
         );
         const RAW: RawWaker = RawWaker::new(ptr::null(), &VTABLE);
+        const WAKER_REF: &Waker = &Waker { waker: RAW };
 
-        Waker { waker: RAW }
+        WAKER_REF
     }
 
     /// Get a reference to the underlying [`RawWaker`].

std/src/sys/mod.rs

@@ -1,124 +1,10 @@
-//! Platform-dependent platform abstraction.
-//!
-//! The `std::sys` module is the abstracted interface through which
-//! `std` talks to the underlying operating system. It has different
-//! implementations for different operating system families, today
-//! just Unix and Windows, and initial support for Redox.
-//!
-//! The centralization of platform-specific code in this module is
-//! enforced by the "platform abstraction layer" tidy script in
-//! `tools/tidy/src/pal.rs`.
-//!
-//! This module is closely related to the platform-independent system
-//! integration code in `std::sys_common`. See that module's
-//! documentation for details.
-//!
-//! In the future it would be desirable for the independent
-//! implementations of this module to be extracted to their own crates
-//! that `std` can link to, thus enabling their implementation
-//! out-of-tree via crate replacement. Though due to the complex
-//! inter-dependencies within `std` that will be a challenging goal to
-//! achieve.
+/// The PAL (platform abstraction layer) contains platform-specific abstractions
+/// for implementing the features in the other submodules, e.g. UNIX file
+/// descriptors.
+mod pal;
 
-#![allow(missing_debug_implementations)]
-
-pub mod common;
 mod personality;
 
-cfg_if::cfg_if! {
-    if #[cfg(unix)] {
-        mod unix;
-        pub use self::unix::*;
-    } else if #[cfg(windows)] {
-        mod windows;
-        pub use self::windows::*;
-    } else if #[cfg(target_os = "solid_asp3")] {
-        mod solid;
-        pub use self::solid::*;
-    } else if #[cfg(target_os = "hermit")] {
-        mod hermit;
-        pub use self::hermit::*;
-    } else if #[cfg(target_os = "wasi")] {
-        mod wasi;
-        pub use self::wasi::*;
-    } else if #[cfg(target_family = "wasm")] {
-        mod wasm;
-        pub use self::wasm::*;
-    } else if #[cfg(target_os = "xous")] {
-        mod xous;
-        pub use self::xous::*;
-    } else if #[cfg(target_os = "uefi")] {
-        mod uefi;
-        pub use self::uefi::*;
-    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
-        mod sgx;
-        pub use self::sgx::*;
-    } else if #[cfg(target_os = "teeos")] {
-        mod teeos;
-        pub use self::teeos::*;
-    } else {
-        mod unsupported;
-        pub use self::unsupported::*;
-    }
-}
-
-cfg_if::cfg_if! {
-    // Fuchsia components default to full backtrace.
-    if #[cfg(target_os = "fuchsia")] {
-        pub const FULL_BACKTRACE_DEFAULT: bool = true;
-    } else {
-        pub const FULL_BACKTRACE_DEFAULT: bool = false;
-    }
-}
-
-#[cfg(not(test))]
-cfg_if::cfg_if! {
-    if #[cfg(target_os = "android")] {
-        pub use self::android::log2f32;
-        pub use self::android::log2f64;
-    } else {
-        #[inline]
-        pub fn log2f32(n: f32) -> f32 {
-            unsafe { crate::intrinsics::log2f32(n) }
-        }
-
-        #[inline]
-        pub fn log2f64(n: f64) -> f64 {
-            unsafe { crate::intrinsics::log2f64(n) }
-        }
-    }
-}
-
-// Solaris/Illumos requires a wrapper around log, log2, and log10 functions
-// because of their non-standard behavior (e.g., log(-n) returns -Inf instead
-// of expected NaN).
-#[cfg(not(test))]
-#[cfg(any(target_os = "solaris", target_os = "illumos"))]
-#[inline]
-pub fn log_wrapper<F: Fn(f64) -> f64>(n: f64, log_fn: F) -> f64 {
-    if n.is_finite() {
-        if n > 0.0 {
-            log_fn(n)
-        } else if n == 0.0 {
-            f64::NEG_INFINITY // log(0) = -Inf
-        } else {
-            f64::NAN // log(-n) = NaN
-        }
-    } else if n.is_nan() {
-        n // log(NaN) = NaN
-    } else if n > 0.0 {
-        n // log(Inf) = Inf
-    } else {
-        f64::NAN // log(-Inf) = NaN
-    }
-}
-
-#[cfg(not(test))]
-#[cfg(not(any(target_os = "solaris", target_os = "illumos")))]
-#[inline]
-pub fn log_wrapper<F: Fn(f64) -> f64>(n: f64, log_fn: F) -> f64 {
-    log_fn(n)
-}
-
-#[cfg(not(target_os = "uefi"))]
-pub type RawOsError = i32;
+// FIXME(117276): remove this, move feature implementations into individual
+//                submodules.
+pub use pal::*;