Rollup of 7 pull requests

compiler/rustc_resolve/src/diagnostics.rs

@@ -1617,7 +1617,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             let post = format!(", consider renaming `{}` into `{snippet}`", suggestion.candidate);
             (span, snippet, post)
         } else {
-            (span, suggestion.candidate.to_string(), String::new())
+            (span, suggestion.candidate.to_ident_string(), String::new())
         };
         let msg = match suggestion.target {
             SuggestionTarget::SimilarlyNamed => format!(

library/alloc/src/ffi/c_str.rs

@@ -41,6 +41,7 @@ use crate::sync::Arc;
 /// or anything that implements <code>[Into]<[Vec]<[u8]>></code> (for
 /// example, you can build a `CString` straight out of a [`String`] or
 /// a <code>&[str]</code>, since both implement that trait).
+/// You can create a `CString` from a literal with `CString::from(c"Text")`.
 ///
 /// The [`CString::new`] method will actually check that the provided <code>&[[u8]]</code>
 /// does not have 0 bytes in the middle, and return an error if it
@@ -1069,27 +1070,22 @@ impl CStr {
     ///
     /// # Examples
     ///
-    /// Calling `to_string_lossy` on a `CStr` containing valid UTF-8:
+    /// Calling `to_string_lossy` on a `CStr` containing valid UTF-8. The leading
+    /// `c` on the string literal denotes a `CStr`.
     ///
     /// ```
     /// use std::borrow::Cow;
-    /// use std::ffi::CStr;
     ///
-    /// let cstr = CStr::from_bytes_with_nul(b"Hello World\0")
-    ///                  .expect("CStr::from_bytes_with_nul failed");
-    /// assert_eq!(cstr.to_string_lossy(), Cow::Borrowed("Hello World"));
+    /// assert_eq!(c"Hello World".to_string_lossy(), Cow::Borrowed("Hello World"));
     /// ```
     ///
     /// Calling `to_string_lossy` on a `CStr` containing invalid UTF-8:
     ///
     /// ```
     /// use std::borrow::Cow;
-    /// use std::ffi::CStr;
     ///
-    /// let cstr = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0")
-    ///                  .expect("CStr::from_bytes_with_nul failed");
     /// assert_eq!(
-    ///     cstr.to_string_lossy(),
+    ///     c"Hello \xF0\x90\x80World".to_string_lossy(),
     ///     Cow::Owned(String::from("Hello �World")) as Cow<'_, str>
     /// );
     /// ```

library/core/src/ffi/c_str.rs

@@ -23,28 +23,32 @@ use crate::str;
 ///
 /// This type represents a borrowed reference to a nul-terminated
 /// array of bytes. It can be constructed safely from a <code>&[[u8]]</code>
-/// slice, or unsafely from a raw `*const c_char`. It can then be
-/// converted to a Rust <code>&[str]</code> by performing UTF-8 validation, or
-/// into an owned `CString`.
+/// slice, or unsafely from a raw `*const c_char`. It can be expressed as a
+/// literal in the form `c"Hello world"`.
+///
+/// The `CStr` can then be converted to a Rust <code>&[str]</code> by performing
+/// UTF-8 validation, or into an owned `CString`.
 ///
 /// `&CStr` is to `CString` as <code>&[str]</code> is to `String`: the former
 /// in each pair are borrowed references; the latter are owned
 /// strings.
 ///
 /// Note that this structure does **not** have a guaranteed layout (the `repr(transparent)`
-/// notwithstanding) and is not recommended to be placed in the signatures of FFI functions.
-/// Instead, safe wrappers of FFI functions may leverage the unsafe [`CStr::from_ptr`] constructor
-/// to provide a safe interface to other consumers.
+/// notwithstanding) and should not be placed in the signatures of FFI functions.
+/// Instead, safe wrappers of FFI functions may leverage [`CStr::as_ptr`] and the unsafe
+/// [`CStr::from_ptr`] constructor to provide a safe interface to other consumers.
 ///
 /// # Examples
 ///
 /// Inspecting a foreign C string:
 ///
-/// ```ignore (extern-declaration)
+/// ```
 /// use std::ffi::CStr;
 /// use std::os::raw::c_char;
 ///
+/// # /* Extern functions are awkward in doc comments - fake it instead
 /// extern "C" { fn my_string() -> *const c_char; }
+/// # */ unsafe extern "C" fn my_string() -> *const c_char { c"hello".as_ptr() }
 ///
 /// unsafe {
 ///     let slice = CStr::from_ptr(my_string());
@@ -54,12 +58,14 @@ use crate::str;
 ///
 /// Passing a Rust-originating C string:
 ///
-/// ```ignore (extern-declaration)
+/// ```
 /// use std::ffi::{CString, CStr};
 /// use std::os::raw::c_char;
 ///
 /// fn work(data: &CStr) {
+/// #   /* Extern functions are awkward in doc comments - fake it instead
 ///     extern "C" { fn work_with(data: *const c_char); }
+/// #   */ unsafe extern "C" fn work_with(s: *const c_char) {}
 ///
 ///     unsafe { work_with(data.as_ptr()) }
 /// }
@@ -70,11 +76,13 @@ use crate::str;
 ///
 /// Converting a foreign C string into a Rust `String`:
 ///
-/// ```ignore (extern-declaration)
+/// ```
 /// use std::ffi::CStr;
 /// use std::os::raw::c_char;
 ///
+/// # /* Extern functions are awkward in doc comments - fake it instead
 /// extern "C" { fn my_string() -> *const c_char; }
+/// # */ unsafe extern "C" fn my_string() -> *const c_char { c"hello".as_ptr() }
 ///
 /// fn my_string_safe() -> String {
 ///     let cstr = unsafe { CStr::from_ptr(my_string()) };
@@ -241,16 +249,16 @@ impl CStr {
     ///
     /// # Examples
     ///
-    /// ```ignore (extern-declaration)
+    /// ```
     /// use std::ffi::{c_char, CStr};
     ///
-    /// extern "C" {
-    ///     fn my_string() -> *const c_char;
+    /// fn my_string() -> *const c_char {
+    ///     c"hello".as_ptr()
     /// }
     ///
     /// unsafe {
     ///     let slice = CStr::from_ptr(my_string());
-    ///     println!("string returned: {}", slice.to_str().unwrap());
+    ///     assert_eq!(slice.to_str().unwrap(), "hello");
     /// }
     /// ```
     ///
@@ -264,6 +272,8 @@ impl CStr {
     ///     BYTES.as_ptr().cast()
     /// };
     /// const HELLO: &CStr = unsafe { CStr::from_ptr(HELLO_PTR) };
+    ///
+    /// assert_eq!(c"Hello, world!", HELLO);
     /// ```
     ///
     /// [valid]: core::ptr#safety
@@ -549,6 +559,7 @@ impl CStr {
     ///
     /// let empty_cstr = CStr::from_bytes_with_nul(b"\0")?;
     /// assert!(empty_cstr.is_empty());
+    /// assert!(c"".is_empty());
     /// # Ok(())
     /// # }
     /// ```

library/core/src/ptr/const_ptr.rs

@@ -358,6 +358,54 @@ impl<T: ?Sized> *const T {
         if self.is_null() { None } else { unsafe { Some(&*self) } }
     }
 
+    /// Returns a shared reference to the value behind the pointer.
+    /// If the pointer may be null or the value may be uninitialized, [`as_uninit_ref`] must be used instead.
+    /// If the pointer may be null, but the value is known to have been initialized, [`as_ref`] must be used instead.
+    ///
+    /// [`as_ref`]: #method.as_ref
+    /// [`as_uninit_ref`]: #method.as_uninit_ref
+    ///
+    /// # Safety
+    ///
+    /// When calling this method, you have to ensure that all of the following is true:
+    ///
+    /// * The pointer must be properly aligned.
+    ///
+    /// * It must be "dereferenceable" in the sense defined in [the module documentation].
+    ///
+    /// * The pointer must point to an initialized instance of `T`.
+    ///
+    /// * You must enforce Rust's aliasing rules, since the returned lifetime `'a` is
+    ///   arbitrarily chosen and does not necessarily reflect the actual lifetime of the data.
+    ///   In particular, while this reference exists, the memory the pointer points to must
+    ///   not get mutated (except inside `UnsafeCell`).
+    ///
+    /// This applies even if the result of this method is unused!
+    /// (The part about being initialized is not yet fully decided, but until
+    /// it is, the only safe approach is to ensure that they are indeed initialized.)
+    ///
+    /// [the module documentation]: crate::ptr#safety
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ptr_as_ref_unchecked)]
+    /// let ptr: *const u8 = &10u8 as *const u8;
+    ///
+    /// unsafe {
+    ///     println!("We got back the value: {}!", ptr.as_ref_unchecked());
+    /// }
+    /// ```
+    // FIXME: mention it in the docs for `as_ref` and `as_uninit_ref` once stabilized.
+    #[unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
+    #[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
+    #[inline]
+    #[must_use]
+    pub const unsafe fn as_ref_unchecked<'a>(self) -> &'a T {
+        // SAFETY: the caller must guarantee that `self` is valid for a reference
+        unsafe { &*self }
+    }
+
     /// Returns `None` if the pointer is null, or else returns a shared reference to
     /// the value wrapped in `Some`. In contrast to [`as_ref`], this does not require
     /// that the value has to be initialized.

library/core/src/ptr/mut_ptr.rs

@@ -367,6 +367,57 @@ impl<T: ?Sized> *mut T {
         if self.is_null() { None } else { unsafe { Some(&*self) } }
     }
 
+    /// Returns a shared reference to the value behind the pointer.
+    /// If the pointer may be null or the value may be uninitialized, [`as_uninit_ref`] must be used instead.
+    /// If the pointer may be null, but the value is known to have been initialized, [`as_ref`] must be used instead.
+    ///
+    /// For the mutable counterpart see [`as_mut_unchecked`].
+    ///
+    /// [`as_ref`]: #method.as_ref
+    /// [`as_uninit_ref`]: #method.as_uninit_ref
+    /// [`as_mut_unchecked`]: #method.as_mut_unchecked
+    ///
+    /// # Safety
+    ///
+    /// When calling this method, you have to ensure that all of the following is true:
+    ///
+    /// * The pointer must be properly aligned.
+    ///
+    /// * It must be "dereferenceable" in the sense defined in [the module documentation].
+    ///
+    /// * The pointer must point to an initialized instance of `T`.
+    ///
+    /// * You must enforce Rust's aliasing rules, since the returned lifetime `'a` is
+    ///   arbitrarily chosen and does not necessarily reflect the actual lifetime of the data.
+    ///   In particular, while this reference exists, the memory the pointer points to must
+    ///   not get mutated (except inside `UnsafeCell`).
+    ///
+    /// This applies even if the result of this method is unused!
+    /// (The part about being initialized is not yet fully decided, but until
+    /// it is, the only safe approach is to ensure that they are indeed initialized.)
+    ///
+    /// [the module documentation]: crate::ptr#safety
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ptr_as_ref_unchecked)]
+    /// let ptr: *mut u8 = &mut 10u8 as *mut u8;
+    ///
+    /// unsafe {
+    ///     println!("We got back the value: {}!", ptr.as_ref_unchecked());
+    /// }
+    /// ```
+    // FIXME: mention it in the docs for `as_ref` and `as_uninit_ref` once stabilized.
+    #[unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
+    #[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
+    #[inline]
+    #[must_use]
+    pub const unsafe fn as_ref_unchecked<'a>(self) -> &'a T {
+        // SAFETY: the caller must guarantee that `self` is valid for a reference
+        unsafe { &*self }
+    }
+
     /// Returns `None` if the pointer is null, or else returns a shared reference to
     /// the value wrapped in `Some`. In contrast to [`as_ref`], this does not require
     /// that the value has to be initialized.
@@ -688,6 +739,58 @@ impl<T: ?Sized> *mut T {
         if self.is_null() { None } else { unsafe { Some(&mut *self) } }
     }
 
+    /// Returns a unique reference to the value behind the pointer.
+    /// If the pointer may be null or the value may be uninitialized, [`as_uninit_mut`] must be used instead.
+    /// If the pointer may be null, but the value is known to have been initialized, [`as_mut`] must be used instead.
+    ///
+    /// For the shared counterpart see [`as_ref_unchecked`].
+    ///
+    /// [`as_mut`]: #method.as_mut
+    /// [`as_uninit_mut`]: #method.as_uninit_mut
+    /// [`as_ref_unchecked`]: #method.as_mut_unchecked
+    ///
+    /// # Safety
+    ///
+    /// When calling this method, you have to ensure that all of the following is true:
+    ///
+    /// * The pointer must be properly aligned.
+    ///
+    /// * It must be "dereferenceable" in the sense defined in [the module documentation].
+    ///
+    /// * The pointer must point to an initialized instance of `T`.
+    ///
+    /// * You must enforce Rust's aliasing rules, since the returned lifetime `'a` is
+    ///   arbitrarily chosen and does not necessarily reflect the actual lifetime of the data.
+    ///   In particular, while this reference exists, the memory the pointer points to must
+    ///   not get mutated (except inside `UnsafeCell`).
+    ///
+    /// This applies even if the result of this method is unused!
+    /// (The part about being initialized is not yet fully decided, but until
+    /// it is, the only safe approach is to ensure that they are indeed initialized.)
+    ///
+    /// [the module documentation]: crate::ptr#safety
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ptr_as_ref_unchecked)]
+    /// let mut s = [1, 2, 3];
+    /// let ptr: *mut u32 = s.as_mut_ptr();
+    /// let first_value = unsafe { ptr.as_mut_unchecked() };
+    /// *first_value = 4;
+    /// # assert_eq!(s, [4, 2, 3]);
+    /// println!("{s:?}"); // It'll print: "[4, 2, 3]".
+    /// ```
+    // FIXME: mention it in the docs for `as_mut` and `as_uninit_mut` once stabilized.
+    #[unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
+    #[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
+    #[inline]
+    #[must_use]
+    pub const unsafe fn as_mut_unchecked<'a>(self) -> &'a mut T {
+        // SAFETY: the caller must guarantee that `self` is valid for a reference
+        unsafe { &mut *self }
+    }
+
     /// Returns `None` if the pointer is null, or else returns a unique reference to
     /// the value wrapped in `Some`. In contrast to [`as_mut`], this does not require
     /// that the value has to be initialized.

library/core/src/time.rs

@@ -1437,10 +1437,10 @@ impl TryFromFloatSecsError {
     const fn description(&self) -> &'static str {
         match self.kind {
             TryFromFloatSecsErrorKind::Negative => {
-                "can not convert float seconds to Duration: value is negative"
+                "cannot convert float seconds to Duration: value is negative"
             }
             TryFromFloatSecsErrorKind::OverflowOrNan => {
-                "can not convert float seconds to Duration: value is either too big or NaN"
+                "cannot convert float seconds to Duration: value is either too big or NaN"
             }
         }
     }

library/std/src/alloc.rs

@@ -353,6 +353,12 @@ fn default_alloc_error_hook(layout: Layout) {
     if unsafe { __rust_alloc_error_handler_should_panic != 0 } {
         panic!("memory allocation of {} bytes failed", layout.size());
     } else {
+        // This is the default path taken on OOM, and the only path taken on stable with std.
+        // Crucially, it does *not* call any user-defined code, and therefore users do not have to
+        // worry about allocation failure causing reentrancy issues. That makes it different from
+        // the default `__rdl_oom` defined in alloc (i.e., the default alloc error handler that is
+        // called when there is no `#[alloc_error_handler]`), which triggers a regular panic and
+        // thus can invoke a user-defined panic hook, executing arbitrary user-defined code.
         rtprintpanic!("memory allocation of {} bytes failed\n", layout.size());
     }
 }

src/ci/github-actions/jobs.yml

@@ -36,6 +36,17 @@ runners:
     os: [ self-hosted, ARM64, linux ]
 
 envs:
+  env-x86_64-apple-tests: &env-x86_64-apple-tests
+    SCRIPT: ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc --skip tests/run-make-fulldeps
+    RUST_CONFIGURE_ARGS: --build=x86_64-apple-darwin --enable-sanitizers --enable-profiler --set rust.jemalloc
+    RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
+    MACOSX_DEPLOYMENT_TARGET: 10.12
+    MACOSX_STD_DEPLOYMENT_TARGET: 10.12
+    SELECT_XCODE: /Applications/Xcode_14.3.1.app
+    NO_LLVM_ASSERTIONS: 1
+    NO_DEBUG_ASSERTIONS: 1
+    NO_OVERFLOW_CHECKS: 1
+
   production:
     &production
     DEPLOY_BUCKET: rust-lang-ci2
@@ -272,16 +283,8 @@ auto:
     <<: *job-macos-xl
 
   - image: x86_64-apple-1
-    env: &env-x86_64-apple-tests
-      SCRIPT: ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc --skip tests/run-make-fulldeps
-      RUST_CONFIGURE_ARGS: --build=x86_64-apple-darwin --enable-sanitizers --enable-profiler --set rust.jemalloc
-      RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
-      MACOSX_DEPLOYMENT_TARGET: 10.12
-      MACOSX_STD_DEPLOYMENT_TARGET: 10.12
-      SELECT_XCODE: /Applications/Xcode_14.3.1.app
-      NO_LLVM_ASSERTIONS: 1
-      NO_DEBUG_ASSERTIONS: 1
-      NO_OVERFLOW_CHECKS: 1
+    env:
+      <<: *env-x86_64-apple-tests
     <<: *job-macos-xl
 
   - image: x86_64-apple-2