Rollup of 16 pull requests

RELEASES.md

@@ -12,6 +12,7 @@ Compiler
 - [Added tier 3\* support for the `armv5te-unknown-linux-uclibceabi` target.][78142]
 - [Added tier 3 support for the `aarch64-apple-ios-macabi` target.][77484]
 - [The `x86_64-unknown-freebsd` is now built with the full toolset.][79484]
+- [Dropped support for all cloudabi targets.][78439]
 
 \* Refer to Rust's [platform support page][forge-platform-support] for more
 information on Rust's tiered platform support.
@@ -77,7 +78,6 @@ Compatibility Notes
 - [`#![test]` as an inner attribute is now considered unstable like other inner macro
   attributes, and reports an error by default through the `soft_unstable` lint.][79003]
 - [Overriding a `forbid` lint at the same level that it was set is now a hard error.][78864]
-- [Dropped support for all cloudabi targets.][78439]
 - [You can no longer intercept `panic!` calls by supplying your own macro.][78343] It's
   recommended to use the `#[panic_handler]` attribute to provide your own implementation.
 - [Semi-colons after item statements (e.g. `struct Foo {};`) now produce a warning.][78296]

compiler/rustc_error_codes/src/error_codes/E0542.md

@@ -19,7 +19,7 @@ fn _stable_const_fn() {}
 fn _deprecated_fn() {}
 ```
 
-To fix the issue you need to provide the `since` field.
+To fix this issue, you need to provide the `since` field. Example:
 
 ```
 #![feature(staged_api)]

compiler/rustc_error_codes/src/error_codes/E0546.md

@@ -13,7 +13,7 @@ fn unstable_fn() {}
 fn stable_fn() {}
 ```
 
-To fix the issue you need to provide the `feature` field.
+To fix this issue, you need to provide the `feature` field. Example:
 
 ```
 #![feature(staged_api)]

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2248,13 +2248,18 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     "...",
                 );
                 if let Some(infer::RelateParamBound(_, t)) = origin {
+                    let return_impl_trait = self
+                        .in_progress_typeck_results
+                        .map(|typeck_results| typeck_results.borrow().hir_owner)
+                        .and_then(|owner| self.tcx.return_type_impl_trait(owner))
+                        .is_some();
                     let t = self.resolve_vars_if_possible(t);
                     match t.kind() {
                         // We've got:
                         // fn get_later<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
                         // suggest:
                         // fn get_later<'a, G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_ + 'a
-                        ty::Closure(_, _substs) | ty::Opaque(_, _substs) => {
+                        ty::Closure(_, _substs) | ty::Opaque(_, _substs) if return_impl_trait => {
                             new_binding_suggestion(&mut err, type_param_span, bound_kind);
                         }
                         _ => {

compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs

@@ -540,7 +540,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         );
     }
 
-    // Attempt to search similar mutable assosiated items for suggestion.
+    // Attempt to search similar mutable associated items for suggestion.
     // In the future, attempt in all path but initially for RHS of for_loop
     fn suggest_similar_mut_method_for_for_loop(&self, err: &mut DiagnosticBuilder<'_>) {
         let hir = self.infcx.tcx.hir();

compiler/rustc_mir/src/borrow_check/type_check/mod.rs

@@ -2191,19 +2191,18 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     CastKind::Pointer(PointerCast::ArrayToPointer) => {
                         let ty_from = op.ty(body, tcx);
 
-                        let opt_ty_elem = match ty_from.kind() {
-                            ty::RawPtr(ty::TypeAndMut {
-                                mutbl: hir::Mutability::Not,
-                                ty: array_ty,
-                            }) => match array_ty.kind() {
-                                ty::Array(ty_elem, _) => Some(ty_elem),
-                                _ => None,
-                            },
+                        let opt_ty_elem_mut = match ty_from.kind() {
+                            ty::RawPtr(ty::TypeAndMut { mutbl: array_mut, ty: array_ty }) => {
+                                match array_ty.kind() {
+                                    ty::Array(ty_elem, _) => Some((ty_elem, *array_mut)),
+                                    _ => None,
+                                }
+                            }
                             _ => None,
                         };
 
-                        let ty_elem = match opt_ty_elem {
-                            Some(ty_elem) => ty_elem,
+                        let (ty_elem, ty_mut) = match opt_ty_elem_mut {
+                            Some(ty_elem_mut) => ty_elem_mut,
                             None => {
                                 span_mirbug!(
                                     self,
@@ -2215,11 +2214,10 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             }
                         };
 
-                        let ty_to = match ty.kind() {
-                            ty::RawPtr(ty::TypeAndMut {
-                                mutbl: hir::Mutability::Not,
-                                ty: ty_to,
-                            }) => ty_to,
+                        let (ty_to, ty_to_mut) = match ty.kind() {
+                            ty::RawPtr(ty::TypeAndMut { mutbl: ty_to_mut, ty: ty_to }) => {
+                                (ty_to, *ty_to_mut)
+                            }
                             _ => {
                                 span_mirbug!(
                                     self,
@@ -2231,6 +2229,17 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             }
                         };
 
+                        if ty_to_mut == Mutability::Mut && ty_mut == Mutability::Not {
+                            span_mirbug!(
+                                self,
+                                rvalue,
+                                "ArrayToPointer cast from const {:?} to mut {:?}",
+                                ty,
+                                ty_to
+                            );
+                            return;
+                        }
+
                         if let Err(terr) = self.sub_types(
                             ty_elem,
                             ty_to,

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

@@ -468,22 +468,21 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                                 trait_ref,
                                 obligation.cause.body_id,
                             );
-                        } else {
-                            if !have_alt_message {
-                                // Can't show anything else useful, try to find similar impls.
-                                let impl_candidates = self.find_similar_impl_candidates(trait_ref);
-                                self.report_similar_impl_candidates(impl_candidates, &mut err);
-                            }
-                            // Changing mutability doesn't make a difference to whether we have
-                            // an `Unsize` impl (Fixes ICE in #71036)
-                            if !is_unsize {
-                                self.suggest_change_mut(
-                                    &obligation,
-                                    &mut err,
-                                    trait_ref,
-                                    points_at_arg,
-                                );
-                            }
+                        } else if !have_alt_message {
+                            // Can't show anything else useful, try to find similar impls.
+                            let impl_candidates = self.find_similar_impl_candidates(trait_ref);
+                            self.report_similar_impl_candidates(impl_candidates, &mut err);
+                        }
+
+                        // Changing mutability doesn't make a difference to whether we have
+                        // an `Unsize` impl (Fixes ICE in #71036)
+                        if !is_unsize {
+                            self.suggest_change_mut(
+                                &obligation,
+                                &mut err,
+                                trait_ref,
+                                points_at_arg,
+                            );
                         }
 
                         // If this error is due to `!: Trait` not implemented but `(): Trait` is

compiler/rustc_typeck/src/check/cast.rs

@@ -765,9 +765,8 @@ impl<'a, 'tcx> CastCheck<'tcx> {
         m_expr: ty::TypeAndMut<'tcx>,
         m_cast: ty::TypeAndMut<'tcx>,
     ) -> Result<CastKind, CastError> {
-        // array-ptr-cast.
-
-        if m_expr.mutbl == hir::Mutability::Not && m_cast.mutbl == hir::Mutability::Not {
+        // array-ptr-cast: allow mut-to-mut, mut-to-const, const-to-const
+        if m_expr.mutbl == hir::Mutability::Mut || m_cast.mutbl == hir::Mutability::Not {
             if let ty::Array(ety, _) = m_expr.ty.kind() {
                 // Due to the limitations of LLVM global constants,
                 // region pointers end up pointing at copies of

compiler/rustc_typeck/src/collect.rs

@@ -280,7 +280,7 @@ impl ItemCtxt<'tcx> {
         ItemCtxt { tcx, item_def_id }
     }
 
-    pub fn to_ty(&self, ast_ty: &'tcx hir::Ty<'tcx>) -> Ty<'tcx> {
+    pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
         AstConv::ast_ty_to_ty(self, ast_ty)
     }
 

compiler/rustc_typeck/src/lib.rs

@@ -421,8 +421,7 @@ pub fn hir_ty_to_ty<'tcx>(tcx: TyCtxt<'tcx>, hir_ty: &hir::Ty<'_>) -> Ty<'tcx> {
     let env_node_id = tcx.hir().get_parent_item(hir_ty.hir_id);
     let env_def_id = tcx.hir().local_def_id(env_node_id);
     let item_cx = self::collect::ItemCtxt::new(tcx, env_def_id.to_def_id());
-
-    astconv::AstConv::ast_ty_to_ty(&item_cx, hir_ty)
+    item_cx.to_ty(hir_ty)
 }
 
 pub fn hir_trait_to_predicates<'tcx>(

library/core/src/cell.rs

@@ -1622,7 +1622,7 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RefMut<'_, T> {
 /// `UnsafeCell<T>` is a type that wraps some `T` and indicates unsafe interior operations on the
 /// wrapped type. Types with an `UnsafeCell<T>` field are considered to have an 'unsafe interior'.
 /// The `UnsafeCell<T>` type is the only legal way to obtain aliasable data that is considered
-/// mutable. In general, transmuting an `&T` type into an `&mut T` is considered undefined behavior.
+/// mutable. In general, transmuting a `&T` type into a `&mut T` is considered undefined behavior.
 ///
 /// If you have a reference `&SomeStruct`, then normally in Rust all fields of `SomeStruct` are
 /// immutable. The compiler makes optimizations based on the knowledge that `&T` is not mutably

library/core/src/iter/adapters/zip.rs

@@ -198,12 +198,13 @@ where
                 Some((self.a.__iterator_get_unchecked(i), self.b.__iterator_get_unchecked(i)))
             }
         } else if A::may_have_side_effect() && self.index < self.a.size() {
+            let i = self.index;
+            self.index += 1;
             // match the base implementation's potential side effects
-            // SAFETY: we just checked that `self.index` < `self.a.len()`
+            // SAFETY: we just checked that `i` < `self.a.len()`
             unsafe {
-                self.a.__iterator_get_unchecked(self.index);
+                self.a.__iterator_get_unchecked(i);
             }
-            self.index += 1;
             None
         } else {
             None

library/std/src/ffi/os_str.rs

@@ -76,6 +76,10 @@ pub struct OsString {
     inner: Buf,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for OsString {}
+
 /// Borrowed reference to an OS string (see [`OsString`]).
 ///
 /// This type represents a borrowed reference to a string in the operating system's preferred
@@ -100,6 +104,10 @@ pub struct OsStr {
     inner: Slice,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for OsStr {}
+
 impl OsString {
     /// Constructs a new empty `OsString`.
     ///

library/std/src/lib.rs

@@ -582,3 +582,11 @@ include!("keyword_docs.rs");
 // is unconditional, so the unstable feature needs to be defined somewhere.
 #[unstable(feature = "restricted_std", issue = "none")]
 mod __restricted_std_workaround {}
+
+mod sealed {
+    /// This trait being unreachable from outside the crate
+    /// prevents outside implementations of our extension traits.
+    /// This allows adding more trait methods in the future.
+    #[unstable(feature = "sealed", issue = "none")]
+    pub trait Sealed {}
+}

library/std/src/process.rs

@@ -498,6 +498,10 @@ pub struct Command {
     inner: imp::Command,
 }
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for Command {}
+
 impl Command {
     /// Constructs a new `Command` for launching the program at
     /// path `program`, with the following default configuration:
@@ -1375,6 +1379,10 @@ impl From<fs::File> for Stdio {
 #[stable(feature = "process", since = "1.0.0")]
 pub struct ExitStatus(imp::ExitStatus);
 
+/// Allows extension traits within `std`.
+#[unstable(feature = "sealed", issue = "none")]
+impl crate::sealed::Sealed for ExitStatus {}
+
 impl ExitStatus {
     /// Was termination successful? Signal termination is not considered a
     /// success, and success is defined as a zero exit status.

library/std/src/sys/unix/ext/process.rs

@@ -6,20 +6,16 @@ use crate::ffi::OsStr;
 use crate::io;
 use crate::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 use crate::process;
+use crate::sealed::Sealed;
 use crate::sys;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
 
-mod private {
-    /// This trait being unreachable from outside the crate
-    /// prevents other implementations of the `ExitStatusExt` trait,
-    /// which allows potentially adding more trait methods in the future.
-    #[stable(feature = "none", since = "1.51.0")]
-    pub trait Sealed {}
-}
-
 /// Unix-specific extensions to the [`process::Command`] builder.
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait CommandExt {
+pub trait CommandExt: Sealed {
     /// Sets the child process's user ID. This translates to a
     /// `setuid` call in the child process. Failure in the `setuid`
     /// call will cause the spawn to fail.
@@ -193,7 +189,7 @@ impl CommandExt for process::Command {
 /// This trait is sealed: it cannot be implemented outside the standard library.
 /// This is so that future additional methods are not breaking changes.
 #[stable(feature = "rust1", since = "1.0.0")]
-pub trait ExitStatusExt: private::Sealed {
+pub trait ExitStatusExt: Sealed {
     /// Creates a new `ExitStatus` from the raw underlying `i32` return value of
     /// a process.
     #[stable(feature = "exit_status_from", since = "1.12.0")]
@@ -228,9 +224,6 @@ pub trait ExitStatusExt: private::Sealed {
     fn into_raw(self) -> i32;
 }
 
-#[stable(feature = "none", since = "1.51.0")]
-impl private::Sealed for process::ExitStatus {}
-
 #[stable(feature = "rust1", since = "1.0.0")]
 impl ExitStatusExt for process::ExitStatus {
     fn from_raw(raw: i32) -> Self {

library/std/src/sys/unix/os.rs

@@ -22,6 +22,7 @@ use crate::str;
 use crate::sys::cvt;
 use crate::sys::fd;
 use crate::sys_common::mutex::{StaticMutex, StaticMutexGuard};
+use crate::sys_common::rwlock::{RWLockReadGuard, StaticRWLock};
 use crate::vec;
 
 use libc::{c_char, c_int, c_void};
@@ -490,20 +491,20 @@ pub unsafe fn environ() -> *mut *const *const c_char {
     extern "C" {
         static mut environ: *const *const c_char;
     }
-    &mut environ
+    ptr::addr_of_mut!(environ)
 }
 
-pub unsafe fn env_lock() -> StaticMutexGuard {
-    // It is UB to attempt to acquire this mutex reentrantly!
-    static ENV_LOCK: StaticMutex = StaticMutex::new();
-    ENV_LOCK.lock()
+static ENV_LOCK: StaticRWLock = StaticRWLock::new();
+
+pub fn env_read_lock() -> RWLockReadGuard {
+    ENV_LOCK.read_with_guard()
 }
 
 /// Returns a vector of (variable, value) byte-vector pairs for all the
 /// environment variables of the current process.
 pub fn env() -> Env {
     unsafe {
-        let _guard = env_lock();
+        let _guard = env_read_lock();
         let mut environ = *environ();
         let mut result = Vec::new();
         if !environ.is_null() {
@@ -540,7 +541,7 @@ pub fn getenv(k: &OsStr) -> io::Result<Option<OsString>> {
     // always None as well
     let k = CString::new(k.as_bytes())?;
     unsafe {
-        let _guard = env_lock();
+        let _guard = env_read_lock();
         let s = libc::getenv(k.as_ptr()) as *const libc::c_char;
         let ret = if s.is_null() {
             None
@@ -556,7 +557,7 @@ pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
     let v = CString::new(v.as_bytes())?;
 
     unsafe {
-        let _guard = env_lock();
+        let _guard = ENV_LOCK.write_with_guard();
         cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(drop)
     }
 }
@@ -565,7 +566,7 @@ pub fn unsetenv(n: &OsStr) -> io::Result<()> {
     let nbuf = CString::new(n.as_bytes())?;
 
     unsafe {
-        let _guard = env_lock();
+        let _guard = ENV_LOCK.write_with_guard();
         cvt(libc::unsetenv(nbuf.as_ptr())).map(drop)
     }
 }