Rollup of 7 pull requests

RELEASES.md

@@ -1,3 +1,158 @@
+Version 1.60.0 (2022-04-07)
+==========================
+
+Language
+--------
+- [Stabilize `#[cfg(panic = "...")]` for either `"unwind"` or `"abort"`.][93658]
+- [Stabilize `#[cfg(target_has_atomic = "...")]` for each integer size and `"ptr"`.][93824]
+
+Compiler
+--------
+- [Enable combining `+crt-static` and `relocation-model=pic` on `x86_64-unknown-linux-gnu`][86374]
+- [Fixes wrong `unreachable_pub` lints on nested and glob public reexport][87487]
+- [Stabilize `-Z instrument-coverage` as `-C instrument-coverage`][90132]
+- [Stabilize `-Z print-link-args` as `--print link-args`][91606]
+- [Add new Tier 3 target `mips64-openwrt-linux-musl`\*][92300]
+- [Add new Tier 3 target `armv7-unknown-linux-uclibceabi` (softfloat)\*][92383]
+- [Fix invalid removal of newlines from doc comments][92357]
+- [Add kernel target for RustyHermit][92670]
+- [Deny mixing bin crate type with lib crate types][92933]
+- [Make rustc use `RUST_BACKTRACE=full` by default][93566]
+- [Upgrade to LLVM 14][93577]
+
+\* Refer to Rust's [platform support page][platform-support-doc] for more
+   information on Rust's tiered platform support.
+
+Libraries
+---------
+- [Guarantee call order for `sort_by_cached_key`][89621]
+- [Improve `Duration::try_from_secs_f32`/`f64` accuracy by directly processing exponent and mantissa][90247]
+- [Make `Instant::{duration_since, elapsed, sub}` saturating][89926]
+- [Remove non-monotonic clocks workarounds in `Instant::now`][89926]
+- [Make `BuildHasherDefault`, `iter::Empty` and `future::Pending` covariant][92630]
+
+Stabilized APIs
+---------------
+- [`Arc::new_cyclic`][arc_new_cyclic]
+- [`Rc::new_cyclic`][rc_new_cyclic]
+- [`slice::EscapeAscii`][slice_escape_ascii]
+- [`<[u8]>::escape_ascii`][slice_u8_escape_ascii]
+- [`u8::escape_ascii`][u8_escape_ascii]
+- [`Vec::spare_capacity_mut`][vec_spare_capacity_mut]
+- [`MaybeUninit::assume_init_drop`][assume_init_drop]
+- [`MaybeUninit::assume_init_read`][assume_init_read]
+- [`i8::abs_diff`][i8_abs_diff]
+- [`i16::abs_diff`][i16_abs_diff]
+- [`i32::abs_diff`][i32_abs_diff]
+- [`i64::abs_diff`][i64_abs_diff]
+- [`i128::abs_diff`][i128_abs_diff]
+- [`isize::abs_diff`][isize_abs_diff]
+- [`u8::abs_diff`][u8_abs_diff]
+- [`u16::abs_diff`][u16_abs_diff]
+- [`u32::abs_diff`][u32_abs_diff]
+- [`u64::abs_diff`][u64_abs_diff]
+- [`u128::abs_diff`][u128_abs_diff]
+- [`usize::abs_diff`][usize_abs_diff]
+- [`Display for io::ErrorKind`][display_error_kind]
+- [`From<u8> for ExitCode`][from_u8_exit_code]
+- [`Not for !` (the "never" type)][not_never]
+- [_Op_`Assign<$t> for Wrapping<$t>`][wrapping_assign_ops]
+- [`arch::is_aarch64_feature_detected!`][is_aarch64_feature_detected]
+
+Cargo
+-----
+- [Port cargo from `toml-rs` to `toml_edit`][cargo/10086]
+- [Stabilize `-Ztimings` as `--timings`][cargo/10245]
+- [Stabilize namespaced and weak dependency features.][cargo/10269]
+- [Accept more `cargo:rustc-link-arg-*` types from build script output.][cargo/10274]
+- [cargo-new should not add ignore rule on Cargo.lock inside subdirs][cargo/10379]
+
+Misc
+----
+- [Ship docs on Tier 2 platforms by reusing the closest Tier 1 platform docs][92800]
+- [Drop rustc-docs from complete profile][93742]
+- [bootstrap: tidy up flag handling for llvm build][93918]
+
+Compatibility Notes
+-------------------
+- [Remove compiler-rt linking hack on Android][83822]
+- [Mitigations for platforms with non-monotonic clocks have been removed from
+  `Instant::now`][89926]. On platforms that don't provide monotonic clocks, an
+  instant is not guaranteed to be greater than an earlier instant anymore.
+- [`Instant::{duration_since, elapsed, sub}` do not panic anymore on underflow,
+  saturating to `0` instead][89926]. In the real world the panic happened mostly
+  on platforms with buggy monotonic clock implementations rather than catching
+  programming errors like reversing the start and end times. Such programming
+  errors will now results in `0` rather than a panic.
+- In a future release we're planning to increase the baseline requirements for
+  the Linux kernel to version 3.2, and for glibc to version 2.17. We'd love
+  your feedback in [PR #95026][95026].
+
+Internal Changes
+----------------
+
+These changes provide no direct user facing benefits, but represent significant
+improvements to the internals and overall performance of rustc
+and related tools.
+
+- [Switch all libraries to the 2021 edition][92068]
+
+[83822]: https://github.com/rust-lang/rust/pull/83822
+[86374]: https://github.com/rust-lang/rust/pull/86374
+[87487]: https://github.com/rust-lang/rust/pull/87487
+[89621]: https://github.com/rust-lang/rust/pull/89621
+[89926]: https://github.com/rust-lang/rust/pull/89926
+[90132]: https://github.com/rust-lang/rust/pull/90132
+[90247]: https://github.com/rust-lang/rust/pull/90247
+[91606]: https://github.com/rust-lang/rust/pull/91606
+[92068]: https://github.com/rust-lang/rust/pull/92068
+[92300]: https://github.com/rust-lang/rust/pull/92300
+[92357]: https://github.com/rust-lang/rust/pull/92357
+[92383]: https://github.com/rust-lang/rust/pull/92383
+[92630]: https://github.com/rust-lang/rust/pull/92630
+[92670]: https://github.com/rust-lang/rust/pull/92670
+[92800]: https://github.com/rust-lang/rust/pull/92800
+[92933]: https://github.com/rust-lang/rust/pull/92933
+[93566]: https://github.com/rust-lang/rust/pull/93566
+[93577]: https://github.com/rust-lang/rust/pull/93577
+[93658]: https://github.com/rust-lang/rust/pull/93658
+[93742]: https://github.com/rust-lang/rust/pull/93742
+[93824]: https://github.com/rust-lang/rust/pull/93824
+[93918]: https://github.com/rust-lang/rust/pull/93918
+[95026]: https://github.com/rust-lang/rust/pull/95026
+
+[cargo/10086]: https://github.com/rust-lang/cargo/pull/10086
+[cargo/10245]: https://github.com/rust-lang/cargo/pull/10245
+[cargo/10269]: https://github.com/rust-lang/cargo/pull/10269
+[cargo/10274]: https://github.com/rust-lang/cargo/pull/10274
+[cargo/10379]: https://github.com/rust-lang/cargo/pull/10379
+
+[arc_new_cyclic]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html#method.new_cyclic
+[rc_new_cyclic]: https://doc.rust-lang.org/stable/std/rc/struct.Rc.html#method.new_cyclic
+[slice_escape_ascii]: https://doc.rust-lang.org/stable/std/slice/struct.EscapeAscii.html
+[slice_u8_escape_ascii]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.escape_ascii
+[u8_escape_ascii]: https://doc.rust-lang.org/stable/std/primitive.u8.html#method.escape_ascii
+[vec_spare_capacity_mut]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.spare_capacity_mut
+[assume_init_drop]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_drop
+[assume_init_read]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_read
+[i8_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.i8.html#method.abs_diff
+[i16_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.i16.html#method.abs_diff
+[i32_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.i32.html#method.abs_diff
+[i64_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.i64.html#method.abs_diff
+[i128_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.i128.html#method.abs_diff
+[isize_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.isize.html#method.abs_diff
+[u8_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.u8.html#method.abs_diff
+[u16_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.u16.html#method.abs_diff
+[u32_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.u32.html#method.abs_diff
+[u64_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.u64.html#method.abs_diff
+[u128_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.u128.html#method.abs_diff
+[usize_abs_diff]: https://doc.rust-lang.org/stable/std/primitive.usize.html#method.abs_diff
+[display_error_kind]: https://doc.rust-lang.org/stable/std/io/enum.ErrorKind.html#impl-Display
+[from_u8_exit_code]: https://doc.rust-lang.org/stable/std/process/struct.ExitCode.html#impl-From%3Cu8%3E
+[not_never]: https://doc.rust-lang.org/stable/std/primitive.never.html#impl-Not
+[wrapping_assign_ops]: https://doc.rust-lang.org/stable/std/num/struct.Wrapping.html#trait-implementations
+[is_aarch64_feature_detected]: https://doc.rust-lang.org/stable/std/arch/macro.is_aarch64_feature_detected.html
+
 Version 1.59.0 (2022-02-24)
 ==========================
 

compiler/rustc_expand/src/proc_macro_server.rs

@@ -658,16 +658,16 @@ impl server::Literal for Rustc<'_, '_> {
         self.lit(token::Float, Symbol::intern(n), Some(sym::f64))
     }
     fn string(&mut self, string: &str) -> Self::Literal {
-        let mut escaped = String::new();
-        for ch in string.chars() {
-            escaped.extend(ch.escape_debug());
-        }
-        self.lit(token::Str, Symbol::intern(&escaped), None)
+        let quoted = format!("{:?}", string);
+        assert!(quoted.starts_with('"') && quoted.ends_with('"'));
+        let symbol = &quoted[1..quoted.len() - 1];
+        self.lit(token::Str, Symbol::intern(symbol), None)
     }
     fn character(&mut self, ch: char) -> Self::Literal {
-        let mut escaped = String::new();
-        escaped.extend(ch.escape_unicode());
-        self.lit(token::Char, Symbol::intern(&escaped), None)
+        let quoted = format!("{:?}", ch);
+        assert!(quoted.starts_with('\'') && quoted.ends_with('\''));
+        let symbol = &quoted[1..quoted.len() - 1];
+        self.lit(token::Char, Symbol::intern(symbol), None)
     }
     fn byte_string(&mut self, bytes: &[u8]) -> Self::Literal {
         let string = bytes

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -474,6 +474,12 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                             err.span_label(span, explanation);
                         }
 
+                        if let ObligationCauseCode::ObjectCastObligation(obj_ty) = obligation.cause.code().peel_derives() &&
+                           let Some(self_ty) = trait_predicate.self_ty().no_bound_vars() &&
+                           Some(trait_ref.def_id()) == self.tcx.lang_items().sized_trait() {
+                            self.suggest_borrowing_for_object_cast(&mut err, &obligation, self_ty, *obj_ty);
+                        }
+
                         if trait_predicate.is_const_if_const() && obligation.param_env.is_const() {
                             let non_const_predicate = trait_ref.without_const();
                             let non_const_obligation = Obligation {

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -77,6 +77,14 @@ pub trait InferCtxtExt<'tcx> {
         has_custom_message: bool,
     ) -> bool;
 
+    fn suggest_borrowing_for_object_cast(
+        &self,
+        err: &mut Diagnostic,
+        obligation: &PredicateObligation<'tcx>,
+        self_ty: Ty<'tcx>,
+        object_ty: Ty<'tcx>,
+    );
+
     fn suggest_remove_reference(
         &self,
         obligation: &PredicateObligation<'tcx>,
@@ -801,6 +809,35 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
         }
     }
 
+    // Suggest borrowing the type
+    fn suggest_borrowing_for_object_cast(
+        &self,
+        err: &mut Diagnostic,
+        obligation: &PredicateObligation<'tcx>,
+        self_ty: Ty<'tcx>,
+        object_ty: Ty<'tcx>,
+    ) {
+        let ty::Dynamic(predicates, _) = object_ty.kind() else { return; };
+        let self_ref_ty = self.tcx.mk_imm_ref(self.tcx.lifetimes.re_erased, self_ty);
+
+        for predicate in predicates.iter() {
+            if !self.predicate_must_hold_modulo_regions(
+                &obligation.with(predicate.with_self_ty(self.tcx, self_ref_ty)),
+            ) {
+                return;
+            }
+        }
+
+        err.span_suggestion(
+            obligation.cause.span.shrink_to_lo(),
+            &format!(
+                "consider borrowing the value, since `&{self_ty}` can be coerced into `{object_ty}`"
+            ),
+            "&".to_string(),
+            Applicability::MaybeIncorrect,
+        );
+    }
+
     /// Whenever references are used by mistake, like `for (i, e) in &vec.iter().enumerate()`,
     /// suggest removing these references until we reach a type that implements the trait.
     fn suggest_remove_reference(

library/core/src/cell.rs

@@ -1990,9 +1990,106 @@ impl<T> const From<T> for UnsafeCell<T> {
 #[unstable(feature = "coerce_unsized", issue = "27732")]
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<UnsafeCell<U>> for UnsafeCell<T> {}
 
+/// [`UnsafeCell`], but [`Sync`].
+///
+/// This is just an `UnsafeCell`, except it implements `Sync`
+/// if `T` implements `Sync`.
+///
+/// `UnsafeCell` doesn't implement `Sync`, to prevent accidental mis-use.
+/// You can use `SyncUnsafeCell` instead of `UnsafeCell` to allow it to be
+/// shared between threads, if that's intentional.
+/// Providing proper synchronization is still the task of the user,
+/// making this type just as unsafe to use.
+///
+/// See [`UnsafeCell`] for details.
+#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+#[repr(transparent)]
+pub struct SyncUnsafeCell<T: ?Sized> {
+    value: UnsafeCell<T>,
+}
+
+#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+unsafe impl<T: ?Sized + Sync> Sync for SyncUnsafeCell<T> {}
+
+#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+impl<T> SyncUnsafeCell<T> {
+    /// Constructs a new instance of `SyncUnsafeCell` which will wrap the specified value.
+    #[inline]
+    pub const fn new(value: T) -> Self {
+        Self { value: UnsafeCell { value } }
+    }
+
+    /// Unwraps the value.
+    #[inline]
+    pub const fn into_inner(self) -> T {
+        self.value.into_inner()
+    }
+}
+
+#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+impl<T: ?Sized> SyncUnsafeCell<T> {
+    /// Gets a mutable pointer to the wrapped value.
+    ///
+    /// This can be cast to a pointer of any kind.
+    /// Ensure that the access is unique (no active references, mutable or not)
+    /// when casting to `&mut T`, and ensure that there are no mutations
+    /// or mutable aliases going on when casting to `&T`
+    #[inline]
+    pub const fn get(&self) -> *mut T {
+        self.value.get()
+    }
+
+    /// Returns a mutable reference to the underlying data.
+    ///
+    /// This call borrows the `SyncUnsafeCell` mutably (at compile-time) which
+    /// guarantees that we possess the only reference.
+    #[inline]
+    pub const fn get_mut(&mut self) -> &mut T {
+        self.value.get_mut()
+    }
+
+    /// Gets a mutable pointer to the wrapped value.
+    ///
+    /// See [`UnsafeCell::get`] for details.
+    #[inline]
+    pub const fn raw_get(this: *const Self) -> *mut T {
+        // We can just cast the pointer from `SyncUnsafeCell<T>` to `T` because
+        // of #[repr(transparent)] on both SyncUnsafeCell and UnsafeCell.
+        // See UnsafeCell::raw_get.
+        this as *const T as *mut T
+    }
+}
+
+#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+impl<T: Default> Default for SyncUnsafeCell<T> {
+    /// Creates an `SyncUnsafeCell`, with the `Default` value for T.
+    fn default() -> SyncUnsafeCell<T> {
+        SyncUnsafeCell::new(Default::default())
+    }
+}
+
+#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<T> for SyncUnsafeCell<T> {
+    /// Creates a new `SyncUnsafeCell<T>` containing the given value.
+    fn from(t: T) -> SyncUnsafeCell<T> {
+        SyncUnsafeCell::new(t)
+    }
+}
+
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+//#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+impl<T: CoerceUnsized<U>, U> CoerceUnsized<SyncUnsafeCell<U>> for SyncUnsafeCell<T> {}
+
 #[allow(unused)]
-fn assert_coerce_unsized(a: UnsafeCell<&i32>, b: Cell<&i32>, c: RefCell<&i32>) {
+fn assert_coerce_unsized(
+    a: UnsafeCell<&i32>,
+    b: SyncUnsafeCell<&i32>,
+    c: Cell<&i32>,
+    d: RefCell<&i32>,
+) {
     let _: UnsafeCell<&dyn Send> = a;
-    let _: Cell<&dyn Send> = b;
-    let _: RefCell<&dyn Send> = c;
+    let _: SyncUnsafeCell<&dyn Send> = b;
+    let _: Cell<&dyn Send> = c;
+    let _: RefCell<&dyn Send> = d;
 }

library/core/src/fmt/mod.rs

@@ -2,7 +2,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use crate::cell::{Cell, Ref, RefCell, RefMut, UnsafeCell};
+use crate::cell::{Cell, Ref, RefCell, RefMut, SyncUnsafeCell, UnsafeCell};
 use crate::char::EscapeDebugExtArgs;
 use crate::marker::PhantomData;
 use crate::mem;
@@ -2400,6 +2400,13 @@ impl<T: ?Sized> Debug for UnsafeCell<T> {
     }
 }
 
+#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
+impl<T: ?Sized> Debug for SyncUnsafeCell<T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+        f.debug_struct("SyncUnsafeCell").finish_non_exhaustive()
+    }
+}
+
 // If you expected tests to be here, look instead at the core/tests/fmt.rs file,
 // it's a lot easier than creating all of the rt::Piece structures here.
 // There are also tests in the alloc crate, for those that need allocations.

library/core/src/lib.rs

@@ -139,6 +139,7 @@
 #![feature(const_type_id)]
 #![feature(const_type_name)]
 #![feature(const_default_impls)]
+#![feature(const_unsafecell_get_mut)]
 #![feature(core_panic)]
 #![feature(duration_consts_float)]
 #![feature(maybe_uninit_uninit_array)]