Rollup of 7 pull requests

Cargo.lock

@@ -17,7 +17,7 @@ dependencies = [
 name = "alloc"
 version = "0.0.0"
 dependencies = [
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
  "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_xorshift 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -107,7 +107,7 @@ version = "0.1.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.28 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-std-workspace-core 1.0.0",
 ]
@@ -465,7 +465,7 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.8"
+version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.28 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -751,7 +751,7 @@ name = "dlmalloc"
 version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-std-workspace-core 1.0.0",
 ]
@@ -917,7 +917,7 @@ name = "fortanix-sgx-abi"
 version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-std-workspace-core 1.0.0",
 ]
 
@@ -1769,7 +1769,7 @@ dependencies = [
 name = "panic_abort"
 version = "0.0.0"
 dependencies = [
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1779,7 +1779,7 @@ name = "panic_unwind"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "unwind 0.0.0",
@@ -1964,7 +1964,7 @@ name = "profiler_builtins"
 version = "0.0.0"
 dependencies = [
  "cc 1.0.28 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -2499,7 +2499,7 @@ name = "rustc-demangle"
 version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-std-workspace-core 1.0.0",
 ]
 
@@ -2599,7 +2599,7 @@ dependencies = [
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -2826,7 +2826,7 @@ dependencies = [
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -2888,7 +2888,7 @@ dependencies = [
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -3009,7 +3009,7 @@ dependencies = [
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -3276,7 +3276,7 @@ dependencies = [
  "alloc 0.0.0",
  "backtrace-sys 0.1.27 (registry+https://github.com/rust-lang/crates.io-index)",
  "cc 1.0.28 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
  "dlmalloc 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fortanix-sgx-abi 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3849,7 +3849,7 @@ dependencies = [
 name = "unwind"
 version = "0.0.0"
 dependencies = [
- "compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -4045,7 +4045,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum colored 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b0aa3473e85a3161b59845d6096b289bb577874cafeaf75ea1b1beaa6572c7fc"
 "checksum commoncrypto 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d056a8586ba25a1e4d61cb090900e495952c7886786fc55f909ab2f819b69007"
 "checksum commoncrypto-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1fed34f46747aa73dfaa578069fd8279d2818ade2b55f38f22a9401c7f4083e2"
-"checksum compiler_builtins 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "a28c3898d0c57b26fa6f92de141ba665fa5ac5179f795db06db408be84302395"
+"checksum compiler_builtins 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "d7de11892d9f9f1bc76d43011c8233d27d58300d629dc9dfb51b6626ef7f6077"
 "checksum compiletest_rs 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)" = "56c799b1f7142badf3b047b4c1f2074cc96b6b784fb2432f2ed9c87da0a03749"
 "checksum constant_time_eq 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8ff012e225ce166d4422e0e78419d901719760f62ae2b7969ca6b564d1b54a9e"
 "checksum core-foundation 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4e2640d6d0bf22e82bed1b73c6aef8d5dd31e5abe6666c57e6d45e2649f4f887"

src/bootstrap/dist.rs

@@ -518,8 +518,7 @@ impl Step for Rustc {
                     .join("bin")
                     .join(&exe);
                 // for the rationale about this rename check `compile::copy_lld_to_sysroot`
-                let dst = image.join(libdir_relative)
-                    .join("rustlib")
+                let dst = image.join("lib/rustlib")
                     .join(&*host)
                     .join("bin")
                     .join(&exe);

src/doc/man/rustc.1

@@ -265,8 +265,8 @@ Optimize with possible levels 0\[en]3
 
 .SH ENVIRONMENT
 
-Some of these affect the output of the compiler, while others affect programs
-which link to the standard library.
+Some of these affect only test harness programs (generated via rustc --test);
+others affect all programs which link to the Rust standard library.
 
 .TP
 \fBRUST_TEST_THREADS\fR

src/libcore/borrow.rs

@@ -32,6 +32,10 @@
 /// on the identical behavior of these additional trait implementations.
 /// These traits will likely appear as additional trait bounds.
 ///
+/// In particular `Eq`, `Ord` and `Hash` must be equivalent for
+/// borrowed and owned values: `x.borrow() == y.borrow()` should give the
+/// same result as `x == y`.
+///
 /// If generic code merely needs to work for all types that can
 /// provide a reference to related type `T`, it is often better to use
 /// [`AsRef<T>`] as more types can safely implement it.

src/libcore/convert.rs

@@ -105,11 +105,13 @@ pub const fn identity<T>(x: T) -> T { x }
 /// `&T` or write a custom function.
 ///
 ///
-/// `AsRef` is very similar to, but serves a slightly different purpose than [`Borrow`]:
+/// `AsRef` has the same signature as [`Borrow`], but `Borrow` is different in few aspects:
 ///
-/// - Use `AsRef` when the goal is to simply convert into a reference
-/// - Use `Borrow` when the goal is related to writing code that is agnostic to
-///   the type of borrow and whether it is a reference or value
+/// - Unlike `AsRef`, `Borrow` has a blanket impl for any `T`, and can be used to accept either
+///   a reference or a value.
+/// - `Borrow` also requires that `Hash`, `Eq` and `Ord` for borrowed value are
+///   equivalent to those of the owned value. For this reason, if you want to
+///   borrow only a single field of a struct you can implement `AsRef`, but not `Borrow`.
 ///
 /// [`Borrow`]: ../../std/borrow/trait.Borrow.html
 ///

src/libcore/hint.rs

@@ -50,15 +50,28 @@ pub unsafe fn unreachable_unchecked() -> ! {
     intrinsics::unreachable()
 }
 
-/// Save power or switch hyperthreads in a busy-wait spin-loop.
+/// Signals the processor that it is entering a busy-wait spin-loop.
 ///
-/// This function is deliberately more primitive than
-/// [`std::thread::yield_now`](../../std/thread/fn.yield_now.html) and
-/// does not directly yield to the system's scheduler.
-/// In some cases it might be useful to use a combination of both functions.
-/// Careful benchmarking is advised.
+/// Upon receiving spin-loop signal the processor can optimize its behavior by, for example, saving
+/// power or switching hyper-threads.
 ///
-/// On some platforms this function may not do anything at all.
+/// This function is different than [`std::thread::yield_now`] which directly yields to the
+/// system's scheduler, whereas `spin_loop` only signals the processor that it is entering a
+/// busy-wait spin-loop without yielding control to the system's scheduler.
+///
+/// Using a busy-wait spin-loop with `spin_loop` is ideally used in situations where a
+/// contended lock is held by another thread executed on a different CPU and where the waiting
+/// times are relatively small. Because entering busy-wait spin-loop does not trigger the system's
+/// scheduler, no overhead for switching threads occurs. However, if the thread holding the
+/// contended lock is running on the same CPU, the spin-loop is likely to occupy an entire CPU slice
+/// before switching to the thread that holds the lock. If the contending lock is held by a thread
+/// on the same CPU or if the waiting times for acquiring the lock are longer, it is often better to
+/// use [`std::thread::yield_now`].
+///
+/// **Note**: On platforms that do not support receiving spin-loop hints this function does not
+/// do anything at all.
+///
+/// [`std::thread::yield_now`]: ../../std/thread/fn.yield_now.html
 #[inline]
 #[unstable(feature = "renamed_spin_loop", issue = "55002")]
 pub fn spin_loop() {

src/libcore/sync/atomic.rs

@@ -124,15 +124,28 @@ use fmt;
 
 use hint::spin_loop;
 
-/// Save power or switch hyperthreads in a busy-wait spin-loop.
+/// Signals the processor that it is entering a busy-wait spin-loop.
 ///
-/// This function is deliberately more primitive than
-/// [`std::thread::yield_now`](../../../std/thread/fn.yield_now.html) and
-/// does not directly yield to the system's scheduler.
-/// In some cases it might be useful to use a combination of both functions.
-/// Careful benchmarking is advised.
+/// Upon receiving spin-loop signal the processor can optimize its behavior by, for example, saving
+/// power or switching hyper-threads.
 ///
-/// On some platforms this function may not do anything at all.
+/// This function is different than [`std::thread::yield_now`] which directly yields to the
+/// system's scheduler, whereas `spin_loop_hint` only signals the processor that it is entering a
+/// busy-wait spin-loop without yielding control to the system's scheduler.
+///
+/// Using a busy-wait spin-loop with `spin_loop_hint` is ideally used in situations where a
+/// contended lock is held by another thread executed on a different CPU and where the waiting
+/// times are relatively small. Because entering busy-wait spin-loop does not trigger the system's
+/// scheduler, no overhead for switching threads occurs. However, if the thread holding the
+/// contended lock is running on the same CPU, the spin-loop is likely to occupy an entire CPU slice
+/// before switching to the thread that holds the lock. If the contending lock is held by a thread
+/// on the same CPU or if the waiting times for acquiring the lock are longer, it is often better to
+/// use [`std::thread::yield_now`].
+///
+/// **Note**: On platforms that do not support receiving spin-loop hints this function does not
+/// do anything at all.
+///
+/// [`std::thread::yield_now`]: ../../../std/thread/fn.yield_now.html
 #[inline]
 #[stable(feature = "spin_loop_hint", since = "1.24.0")]
 pub fn spin_loop_hint() {

src/librustc_codegen_llvm/abi.rs

@@ -518,7 +518,11 @@ impl<'tcx> FnTypeExt<'tcx> for FnType<'tcx, Ty<'tcx>> {
         let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| {
             let is_return = arg_idx.is_none();
             let mut arg = mk_arg_type(ty, arg_idx);
-            if arg.layout.is_zst() {
+            if is_return && arg.layout.abi.is_uninhabited() {
+                // Functions with uninhabited return values are marked `noreturn`,
+                // so we don't actually need to do anything with the value.
+                arg.mode = PassMode::Ignore(IgnoreMode::Uninhabited);
+            } else if arg.layout.is_zst() {
                 // For some forsaken reason, x86_64-pc-windows-gnu
                 // doesn't ignore zero-sized struct arguments.
                 // The same is true for s390x-unknown-linux-gnu
@@ -677,7 +681,8 @@ impl<'tcx> FnTypeExt<'tcx> for FnType<'tcx, Ty<'tcx>> {
         );
 
         let llreturn_ty = match self.ret.mode {
-            PassMode::Ignore(IgnoreMode::Zst) => cx.type_void(),
+            PassMode::Ignore(IgnoreMode::Zst)
+            | PassMode::Ignore(IgnoreMode::Uninhabited) => cx.type_void(),
             PassMode::Ignore(IgnoreMode::CVarArgs) =>
                 bug!("`va_list` should never be a return type"),
             PassMode::Direct(_) | PassMode::Pair(..) => {

src/librustc_codegen_ssa/mir/block.rs

@@ -244,6 +244,12 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 return;
             }
 
+            PassMode::Ignore(IgnoreMode::Uninhabited) => {
+                bx.abort();
+                bx.unreachable();
+                return;
+            }
+
             PassMode::Ignore(IgnoreMode::CVarArgs) => {
                 bug!("C-variadic arguments should never be the return type");
             }

src/librustc_codegen_ssa/mir/mod.rs

@@ -521,7 +521,8 @@ fn arg_local_refs<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
                 PassMode::Ignore(IgnoreMode::Zst) => {
                     return local(OperandRef::new_zst(bx, arg.layout));
                 }
-                PassMode::Ignore(IgnoreMode::CVarArgs) => {}
+                PassMode::Ignore(IgnoreMode::CVarArgs)
+                | PassMode::Ignore(IgnoreMode::Uninhabited) => {}
                 PassMode::Direct(_) => {
                     let llarg = bx.get_param(llarg_idx);
                     bx.set_value_name(llarg, &name);

src/librustc_target/abi/call/mod.rs

@@ -29,6 +29,8 @@ pub enum IgnoreMode {
     CVarArgs,
     /// A zero-sized type.
     Zst,
+    /// An uninhabited type.
+    Uninhabited,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]

src/libstd/Cargo.toml

@@ -19,7 +19,7 @@ panic_unwind = { path = "../libpanic_unwind", optional = true }
 panic_abort = { path = "../libpanic_abort" }
 core = { path = "../libcore" }
 libc = { version = "0.2.51", default-features = false, features = ['rustc-dep-of-std'] }
-compiler_builtins = { version = "0.1.8" }
+compiler_builtins = { version = "0.1.9" }
 profiler_builtins = { path = "../libprofiler_builtins", optional = true }
 unwind = { path = "../libunwind" }
 rustc-demangle = { version = "0.1.10", features = ['rustc-dep-of-std'] }

src/libstd/fs.rs

@@ -881,6 +881,10 @@ impl OpenOptions {
     }
 }
 
+impl AsInner<fs_imp::OpenOptions> for OpenOptions {
+    fn as_inner(&self) -> &fs_imp::OpenOptions { &self.0 }
+}
+
 impl AsInnerMut<fs_imp::OpenOptions> for OpenOptions {
     fn as_inner_mut(&mut self) -> &mut fs_imp::OpenOptions { &mut self.0 }
 }
@@ -1104,6 +1108,10 @@ impl AsInner<fs_imp::FileAttr> for Metadata {
     fn as_inner(&self) -> &fs_imp::FileAttr { &self.0 }
 }
 
+impl FromInner<fs_imp::FileAttr> for Metadata {
+    fn from_inner(attr: fs_imp::FileAttr) -> Metadata { Metadata(attr) }
+}
+
 impl Permissions {
     /// Returns `true` if these permissions describe a readonly (unwritable) file.
     ///