rust-lang · bors · Jun 9, 2025 · May 14, 2025 · May 7, 2025 · Jun 4, 2025
diff --git a/Cargo.lock b/Cargo.lock
@@ -3130,11 +3130,12 @@ dependencies = [
 
 [[package]]
 name = "rustc-build-sysroot"
-version = "0.5.7"
+version = "0.5.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "10edc2e4393515193bd766e2f6c050b0536a68e56f2b6d56c07ababfdc114ff0"
+checksum = "16d115ad7e26e0d1337f64ae6598f758194696afc2e9f34c8a6f24582529c3dc"
 dependencies = [
  "anyhow",
+ "regex",
  "rustc_version",
  "tempfile",
  "walkdir",

diff --git a/compiler/rustc_codegen_gcc/build_system/build_sysroot/Cargo.toml b/compiler/rustc_codegen_gcc/build_system/build_sysroot/Cargo.toml
@@ -6,7 +6,6 @@ resolver = "2"
 
 [dependencies]
 core = { path = "./sysroot_src/library/core" }
-compiler_builtins = "0.1"
 alloc = { path = "./sysroot_src/library/alloc" }
 std = { path = "./sysroot_src/library/std", features = ["panic_unwind", "backtrace"] }
 test = { path = "./sysroot_src/library/test" }
@@ -16,6 +15,7 @@ proc_macro = { path = "./sysroot_src/library/proc_macro" }
 rustc-std-workspace-core = { path = "./sysroot_src/library/rustc-std-workspace-core" }
 rustc-std-workspace-alloc = { path = "./sysroot_src/library/rustc-std-workspace-alloc" }
 rustc-std-workspace-std = { path = "./sysroot_src/library/rustc-std-workspace-std" }
+compiler_builtins = { path = "./sysroot_src/library/compiler-builtins/compiler-builtins" }
 
 # For compiler-builtins we always use a high number of codegen units.
 # The goal here is to place every single intrinsic into its own object

diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
@@ -382,6 +382,8 @@ declare_features! (
     (accepted, self_in_typedefs, "1.32.0", Some(49303)),
     /// Allows `Self` struct constructor (RFC 2302).
     (accepted, self_struct_ctor, "1.32.0", Some(51994)),
+    /// Allows use of x86 SHA512, SM3 and SM4 target-features and intrinsics
+    (accepted, sha512_sm_x86, "CURRENT_RUSTC_VERSION", Some(126624)),
     /// Shortern the tail expression lifetime
     (accepted, shorter_tail_lifetimes, "1.84.0", Some(123739)),
     /// Allows using subslice patterns, `[a, .., b]` and `[a, xs @ .., b]`.

diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
@@ -627,8 +627,6 @@ declare_features! (
     (unstable, return_type_notation, "1.70.0", Some(109417)),
     /// Allows `extern "rust-cold"`.
     (unstable, rust_cold_cc, "1.63.0", Some(97544)),
-    /// Allows use of x86 SHA512, SM3 and SM4 target-features and intrinsics
-    (unstable, sha512_sm_x86, "1.82.0", Some(126624)),
     /// Allows the use of SIMD types in functions declared in `extern` blocks.
     (unstable, simd_ffi, "1.0.0", Some(27731)),
     /// Allows specialization of implementations (RFC 1210).

diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs
@@ -22,7 +22,7 @@ use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_session::lint::builtin::DEAD_CODE;
 use rustc_session::lint::{self, LintExpectationId};
-use rustc_span::{Symbol, sym};
+use rustc_span::{Symbol, kw, sym};
 
 use crate::errors::{
     ChangeFields, IgnoredDerivedImpls, MultipleDeadCodes, ParentInfo, UselessAssignment,
@@ -793,6 +793,17 @@ fn check_item<'tcx>(
             // global_asm! is always live.
             worklist.push((id.owner_id.def_id, ComesFromAllowExpect::No));
         }
+        DefKind::Const => {
+            let item = tcx.hir_item(id);
+            if let hir::ItemKind::Const(ident, ..) = item.kind
+                && ident.name == kw::Underscore
+            {
+                // `const _` is always live, as that syntax only exists for the side effects
+                // of type checking and evaluating the constant expression, and marking them
+                // as dead code would defeat that purpose.
+                worklist.push((id.owner_id.def_id, ComesFromAllowExpect::No));
+            }
+        }
         _ => {}
     }
 }

diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
@@ -455,9 +455,9 @@ static X86_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("rdseed", Stable, &[]),
     ("rtm", Unstable(sym::rtm_target_feature), &[]),
     ("sha", Stable, &["sse2"]),
-    ("sha512", Unstable(sym::sha512_sm_x86), &["avx2"]),
-    ("sm3", Unstable(sym::sha512_sm_x86), &["avx"]),
-    ("sm4", Unstable(sym::sha512_sm_x86), &["avx2"]),
+    ("sha512", Stable, &["avx2"]),
+    ("sm3", Stable, &["avx"]),
+    ("sm4", Stable, &["avx2"]),
     // This cannot actually be toggled, the ABI always fixes it, so it'd make little sense to
     // stabilize. It must be in this list for the ABI check to be able to use it.
     ("soft-float", Stability::Unstable(sym::x87_target_feature), &[]),

diff --git a/library/Cargo.lock b/library/Cargo.lock
@@ -62,11 +62,9 @@ dependencies = [
 [[package]]
 name = "compiler_builtins"
 version = "0.1.160"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6376049cfa92c0aa8b9ac95fae22184b981c658208d4ed8a1dc553cd83612895"
 dependencies = [
  "cc",
- "rustc-std-workspace-core",
+ "core",
 ]
 
 [[package]]
@@ -304,6 +302,7 @@ dependencies = [
 name = "rustc-std-workspace-core"
 version = "1.99.0"
 dependencies = [
+ "compiler_builtins",
  "core",
 ]
 

diff --git a/library/Cargo.toml b/library/Cargo.toml
@@ -50,3 +50,4 @@ rustc-demangle.opt-level = "s"
 rustc-std-workspace-core = { path = 'rustc-std-workspace-core' }
 rustc-std-workspace-alloc = { path = 'rustc-std-workspace-alloc' }
 rustc-std-workspace-std = { path = 'rustc-std-workspace-std' }
+compiler_builtins = { path = "compiler-builtins/compiler-builtins" }
diff --git a/library/alloc/Cargo.toml b/library/alloc/Cargo.toml
@@ -16,7 +16,7 @@ bench = false
 
 [dependencies]
 core = { path = "../core", public = true }
-compiler_builtins = { version = "=0.1.160", features = ['rustc-dep-of-std'] }
+compiler_builtins = { path = "../compiler-builtins/compiler-builtins", features = ["rustc-dep-of-std"] }
 
 [features]
 compiler-builtins-mem = ['compiler_builtins/mem']

diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
@@ -131,7 +131,6 @@
 #![feature(local_waker)]
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_uninit_array_transpose)]
-#![feature(nonnull_provenance)]
 #![feature(panic_internals)]
 #![feature(pattern)]
 #![feature(pin_coerce_unsized_trait)]

diff --git a/library/alloctests/lib.rs b/library/alloctests/lib.rs
@@ -28,7 +28,6 @@
 #![feature(iter_next_chunk)]
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_uninit_array_transpose)]
-#![feature(nonnull_provenance)]
 #![feature(ptr_alignment_type)]
 #![feature(ptr_internals)]
 #![feature(sized_type_properties)]

diff --git a/library/compiler-builtins/compiler-builtins/Cargo.toml b/library/compiler-builtins/compiler-builtins/Cargo.toml
@@ -17,9 +17,7 @@ doctest = false
 test = false
 
 [dependencies]
-# For more information on this dependency see
-# https://github.com/rust-lang/rust/tree/master/library/rustc-std-workspace-core
-core = { version = "1.0.1", optional = true, package = "rustc-std-workspace-core" }
+core = { path = "../../core", optional = true }
 
 [build-dependencies]
 cc = { optional = true, version = "1.2" }

diff --git a/library/compiler-builtins/compiler-builtins/build.rs b/library/compiler-builtins/compiler-builtins/build.rs
@@ -22,6 +22,9 @@ fn main() {
 
     println!("cargo:compiler-rt={}", cwd.join("compiler-rt").display());
 
+    println!("cargo::rustc-check-cfg=cfg(kernel_user_helpers)");
+    println!("cargo::rustc-check-cfg=cfg(feature, values(\"mem-unaligned\"))");
+
     // Emscripten's runtime includes all the builtins
     if target.os == "emscripten" {
         return;
@@ -47,7 +50,6 @@ fn main() {
     }
 
     // These targets have hardware unaligned access support.
-    println!("cargo::rustc-check-cfg=cfg(feature, values(\"mem-unaligned\"))");
     if target.arch.contains("x86_64")
         || target.arch.contains("x86")
         || target.arch.contains("aarch64")
@@ -78,7 +80,6 @@ fn main() {
     // Only emit the ARM Linux atomic emulation on pre-ARMv6 architectures. This
     // includes the old androideabi. It is deprecated but it is available as a
     // rustc target (arm-linux-androideabi).
-    println!("cargo::rustc-check-cfg=cfg(kernel_user_helpers)");
     if llvm_target[0] == "armv4t"
         || llvm_target[0] == "armv5te"
         || target.triple == "arm-linux-androideabi"

diff --git a/library/compiler-builtins/compiler-builtins/src/aarch64_linux.rs b/library/compiler-builtins/compiler-builtins/src/aarch64_linux.rs
@@ -4,7 +4,7 @@
 //! To avoid breaking backwards compat, C toolchains introduced a concept of "outlined atomics",
 //! where atomic operations call into the compiler runtime to dispatch between two depending on
 //! which is supported on the current CPU.
-//! See https://community.arm.com/arm-community-blogs/b/tools-software-ides-blog/posts/making-the-most-of-the-arm-architecture-in-gcc-10#:~:text=out%20of%20line%20atomics for more discussion.
+//! See <https://community.arm.com/arm-community-blogs/b/tools-software-ides-blog/posts/making-the-most-of-the-arm-architecture-in-gcc-10#:~:text=out%20of%20line%20atomics> for more discussion.
 //!
 //! Currently we only support LL/SC, because LSE requires `getauxval` from libc in order to do runtime detection.
 //! Use the `compiler-rt` intrinsics if you want LSE support.

diff --git a/library/compiler-builtins/compiler-builtins/src/arm_linux.rs b/library/compiler-builtins/compiler-builtins/src/arm_linux.rs
@@ -4,12 +4,17 @@ use core::{arch, mem};
 // Kernel-provided user-mode helper functions:
 // https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt
 unsafe fn __kuser_cmpxchg(oldval: u32, newval: u32, ptr: *mut u32) -> bool {
-    let f: extern "C" fn(u32, u32, *mut u32) -> u32 = mem::transmute(0xffff0fc0usize as *const ());
+    // FIXME(volatile): the third parameter is a volatile pointer
+    // SAFETY: kernel docs specify a known address with the given signature
+    let f = unsafe {
+        mem::transmute::<_, extern "C" fn(u32, u32, *mut u32) -> u32>(0xffff0fc0usize as *const ())
+    };
     f(oldval, newval, ptr) == 0
 }
 
 unsafe fn __kuser_memory_barrier() {
-    let f: extern "C" fn() = mem::transmute(0xffff0fa0usize as *const ());
+    // SAFETY: kernel docs specify a known address with the given signature
+    let f = unsafe { mem::transmute::<_, extern "C" fn()>(0xffff0fa0usize as *const ()) };
     f();
 }
 
@@ -67,8 +72,10 @@ fn insert_aligned(aligned: u32, val: u32, shift: u32, mask: u32) -> u32 {
 /// - if `size_of::<T>() == 2`, `ptr` or `ptr` offset by 2 bytes must be valid for a relaxed atomic
 ///   read of 2 bytes.
 /// - if `size_of::<T>() == 4`, `ptr` must be valid for a relaxed atomic read of 4 bytes.
+// FIXME: assert some of the preconditions in debug mode
 unsafe fn atomic_load_aligned<T>(ptr: *mut u32) -> u32 {
-    if mem::size_of::<T>() == 4 {
+    const { assert!(size_of::<T>() <= 4) };
+    if size_of::<T>() == 4 {
         // SAFETY: As `T` has a size of 4, the caller garantees this is sound.
         unsafe { AtomicU32::from_ptr(ptr).load(Ordering::Relaxed) }
     } else {
@@ -100,11 +107,13 @@ unsafe fn atomic_rmw<T, F: Fn(u32) -> u32, G: Fn(u32, u32) -> u32>(ptr: *mut T,
     let (shift, mask) = get_shift_mask(ptr);
 
     loop {
-        let curval_aligned = atomic_load_aligned::<T>(aligned_ptr);
+        // FIXME(safety): preconditions review needed
+        let curval_aligned = unsafe { atomic_load_aligned::<T>(aligned_ptr) };
         let curval = extract_aligned(curval_aligned, shift, mask);
         let newval = f(curval);
         let newval_aligned = insert_aligned(curval_aligned, newval, shift, mask);
-        if __kuser_cmpxchg(curval_aligned, newval_aligned, aligned_ptr) {
+        // FIXME(safety): preconditions review needed
+        if unsafe { __kuser_cmpxchg(curval_aligned, newval_aligned, aligned_ptr) } {
             return g(curval, newval);
         }
     }
@@ -116,13 +125,15 @@ unsafe fn atomic_cmpxchg<T>(ptr: *mut T, oldval: u32, newval: u32) -> u32 {
     let (shift, mask) = get_shift_mask(ptr);
 
     loop {
-        let curval_aligned = atomic_load_aligned::<T>(aligned_ptr);
+        // FIXME(safety): preconditions review needed
+        let curval_aligned = unsafe { atomic_load_aligned::<T>(aligned_ptr) };
         let curval = extract_aligned(curval_aligned, shift, mask);
         if curval != oldval {
             return curval;
         }
         let newval_aligned = insert_aligned(curval_aligned, newval, shift, mask);
-        if __kuser_cmpxchg(curval_aligned, newval_aligned, aligned_ptr) {
+        // FIXME(safety): preconditions review needed
+        if unsafe { __kuser_cmpxchg(curval_aligned, newval_aligned, aligned_ptr) } {
             return oldval;
         }
     }
@@ -132,7 +143,14 @@ macro_rules! atomic_rmw {
     ($name:ident, $ty:ty, $op:expr, $fetch:expr) => {
         intrinsics! {
             pub unsafe extern "C" fn $name(ptr: *mut $ty, val: $ty) -> $ty {
-                atomic_rmw(ptr, |x| $op(x as $ty, val) as u32, |old, new| $fetch(old, new)) as $ty
+                // FIXME(safety): preconditions review needed
+                unsafe {
+                    atomic_rmw(
+                        ptr,
+                        |x| $op(x as $ty, val) as u32,
+                        |old, new| $fetch(old, new)
+                    ) as $ty
+                }
             }
         }
     };
@@ -149,7 +167,8 @@ macro_rules! atomic_cmpxchg {
     ($name:ident, $ty:ty) => {
         intrinsics! {
             pub unsafe extern "C" fn $name(ptr: *mut $ty, oldval: $ty, newval: $ty) -> $ty {
-                atomic_cmpxchg(ptr, oldval as u32, newval as u32) as $ty
+                // FIXME(safety): preconditions review needed
+                unsafe { atomic_cmpxchg(ptr, oldval as u32, newval as u32) as $ty }
             }
         }
     };
@@ -285,6 +304,7 @@ atomic_cmpxchg!(__sync_val_compare_and_swap_4, u32);
 
 intrinsics! {
     pub unsafe extern "C" fn __sync_synchronize() {
-        __kuser_memory_barrier();
+       // SAFETY: preconditions are the same as the calling function.
+       unsafe {  __kuser_memory_barrier() };
     }
 }
diff --git a/library/compiler-builtins/compiler-builtins/src/mem/x86_64.rs b/library/compiler-builtins/compiler-builtins/src/mem/x86_64.rs
@@ -69,7 +69,7 @@ pub unsafe fn copy_backward(dest: *mut u8, src: *const u8, count: usize) {
         "rep movsb",
         "sub $7, %rsi",
         "sub $7, %rdi",
-        "mov {qword_count}, %rcx",
+        "mov {qword_count:r}, %rcx",
         "rep movsq",
         "test {pre_byte_count:e}, {pre_byte_count:e}",
         "add $7, %rsi",
@@ -212,7 +212,7 @@ pub unsafe fn c_string_length(mut s: *const core::ffi::c_char) -> usize {
     let x = {
         let r;
         asm!(
-            "movdqa ({addr}), {dest}",
+            "movdqa ({addr:r}), {dest}",
             addr = in(reg) s,
             dest = out(xmm_reg) r,
             options(att_syntax, nostack),
@@ -232,7 +232,7 @@ pub unsafe fn c_string_length(mut s: *const core::ffi::c_char) -> usize {
         let x = {
             let r;
             asm!(
-                "movdqa ({addr}), {dest}",
+                "movdqa ({addr:r}), {dest}",
                 addr = in(reg) s,
                 dest = out(xmm_reg) r,
                 options(att_syntax, nostack),

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
@@ -197,7 +197,6 @@
 #![feature(riscv_target_feature)]
 #![feature(rtm_target_feature)]
 #![feature(s390x_target_feature)]
-#![feature(sha512_sm_x86)]
 #![feature(sse4a_target_feature)]
 #![feature(tbm_target_feature)]
 #![feature(wasm_target_feature)]

diff --git a/library/core/src/num/niche_types.rs b/library/core/src/num/niche_types.rs
@@ -131,6 +131,8 @@ define_valid_range_type! {
     pub struct NonZeroI32Inner(i32 as u32 in 1..=0xffff_ffff);
     pub struct NonZeroI64Inner(i64 as u64 in 1..=0xffffffff_ffffffff);
     pub struct NonZeroI128Inner(i128 as u128 in 1..=0xffffffffffffffff_ffffffffffffffff);
+
+    pub struct NonZeroCharInner(char as u32 in 1..=0x10ffff);
 }
 
 #[cfg(target_pointer_width = "16")]

diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
@@ -79,6 +79,7 @@ impl_zeroable_primitive!(
     NonZeroI64Inner(i64),
     NonZeroI128Inner(i128),
     NonZeroIsizeInner(isize),
+    NonZeroCharInner(char),
 );
 
 /// A value that is known not to equal zero.

diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
@@ -89,7 +89,8 @@ impl<T: Sized> NonNull<T> {
     /// For more details, see the equivalent method on a raw pointer, [`ptr::without_provenance_mut`].
     ///
     /// This is a [Strict Provenance][crate::ptr#strict-provenance] API.
-    #[unstable(feature = "nonnull_provenance", issue = "135243")]
+    #[stable(feature = "nonnull_provenance", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "nonnull_provenance", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     #[inline]
     pub const fn without_provenance(addr: NonZero<usize>) -> Self {
@@ -132,7 +133,7 @@ impl<T: Sized> NonNull<T> {
     /// For more details, see the equivalent method on a raw pointer, [`ptr::with_exposed_provenance_mut`].
     ///
     /// This is an [Exposed Provenance][crate::ptr#exposed-provenance] API.
-    #[unstable(feature = "nonnull_provenance", issue = "135243")]
+    #[stable(feature = "nonnull_provenance", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub fn with_exposed_provenance(addr: NonZero<usize>) -> Self {
         // SAFETY: we know `addr` is non-zero.
@@ -329,7 +330,7 @@ impl<T: ?Sized> NonNull<T> {
     /// For more details, see the equivalent method on a raw pointer, [`pointer::expose_provenance`].
     ///
     /// This is an [Exposed Provenance][crate::ptr#exposed-provenance] API.
-    #[unstable(feature = "nonnull_provenance", issue = "135243")]
+    #[stable(feature = "nonnull_provenance", since = "CURRENT_RUSTC_VERSION")]
     pub fn expose_provenance(self) -> NonZero<usize> {
         // SAFETY: The pointer is guaranteed by the type to be non-null,
         // meaning that the address will be non-zero.

diff --git a/library/coretests/tests/num/mod.rs b/library/coretests/tests/num/mod.rs
@@ -22,20 +22,19 @@ mod u64;
 mod u8;
 
 mod bignum;
-
 mod const_from;
 mod dec2flt;
+mod float_iter_sum_identity;
 mod flt2dec;
+mod ieee754;
 mod int_log;
 mod int_sqrt;
 mod midpoint;
+mod nan;
+mod niche_types;
 mod ops;
 mod wrapping;
 
-mod float_iter_sum_identity;
-mod ieee754;
-mod nan;
-
 /// Adds the attribute to all items in the block.
 macro_rules! cfg_block {
     ($(#[$attr:meta]{$($it:item)*})*) => {$($(