Auto merge of #140562 - GuillaumeGomez:rollup-j5rbgt3, r=GuillaumeGomez

Rollup of 12 pull requests

Successful merges:

 - #138703 (chore: remove redundant words in comment)
 - #139186 (Refactor `diy_float`)
 - #139343 (Change signature of File::try_lock and File::try_lock_shared)
 - #139780 (docs: Add example to `Iterator::take` with `by_ref`)
 - #139802 (Fix some grammar errors and hyperlinks in doc for `trait Allocator`)
 - #140034 (simd_select_bitmask: the 'padding' bits in the mask are just ignored)
 - #140062 (std: mention `remove_dir_all` can emit `DirectoryNotEmpty` when concurrently written into)
 - #140420 (rustdoc: Fix doctest heuristic for main fn wrapping)
 - #140460 (Fix handling of LoongArch target features not supported by LLVM 19)
 - #140538 (rustc-dev-guide subtree update)
 - #140552 (allow `#[rustc_std_internal_symbol]` in combination with `#[naked]`)
 - #140556 (Improve error output in case `nodejs` or `npm` is not installed for rustdoc-gui test suite)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -273,6 +273,12 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         ("aarch64", "fpmr") => None, // only existed in 18
         ("arm", "fp16") => Some(LLVMFeature::new("fullfp16")),
         // Filter out features that are not supported by the current LLVM version
+        ("loongarch64", "div32" | "lam-bh" | "lamcas" | "ld-seq-sa" | "scq")
+            if get_version().0 < 20 =>
+        {
+            None
+        }
+        // Filter out features that are not supported by the current LLVM version
         ("riscv32" | "riscv64", "zacas") if get_version().0 < 20 => None,
         // Enable the evex512 target feature if an avx512 target feature is enabled.
         ("x86", s) if s.starts_with("avx512") => {

compiler/rustc_error_codes/src/error_codes/E0207.md

@@ -195,7 +195,7 @@ impl<'a> Contains for Foo {
 Please note that unconstrained lifetime parameters are not supported if they are
 being used by an associated type.
 
-In cases where the associated type's lifetime is meant to be tied to the the
+In cases where the associated type's lifetime is meant to be tied to the
 self type, and none of the methods on the trait need ownership or different
 mutability, then an option is to implement the trait on a borrowed type:
 

compiler/rustc_passes/src/check_attr.rs

@@ -625,6 +625,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             sym::naked,
             sym::instruction_set,
             sym::repr,
+            sym::rustc_std_internal_symbol,
             // code generation
             sym::cold,
             // documentation

compiler/rustc_target/src/target_features.rs

@@ -102,6 +102,9 @@ impl Stability {
 // check whether they're named already elsewhere in rust
 // e.g. in stdarch and whether the given name matches LLVM's
 // if it doesn't, to_llvm_feature in llvm_util in rustc_codegen_llvm needs to be adapted.
+// Additionally, if the feature is not available in older version of LLVM supported by the current
+// rust, the same function must be updated to filter out these features to avoid triggering
+// warnings.
 //
 // Also note that all target features listed here must be purely additive: for target_feature 1.1 to
 // be sound, we can never allow features like `+soft-float` (on x86) to be controlled on a

library/core/src/alloc/mod.rs

@@ -90,7 +90,7 @@ impl fmt::Display for AllocError {
 /// # Safety
 ///
 /// Memory blocks that are [*currently allocated*] by an allocator,
-/// must point to valid memory, and retain their validity while until either:
+/// must point to valid memory, and retain their validity until either:
 ///  - the memory block is deallocated, or
 ///  - the allocator is dropped.
 ///
@@ -112,7 +112,9 @@ pub unsafe trait Allocator {
     ///
     /// The returned block of memory remains valid as long as it is [*currently allocated*] and the shorter of:
     ///   - the borrow-checker lifetime of the allocator type itself.
-    ///   - as long as at the allocator and all its clones has not been dropped.
+    ///   - as long as the allocator and all its clones have not been dropped.
+    ///
+    /// [*currently allocated*]: #currently-allocated-memory
     ///
     /// # Errors
     ///

library/core/src/intrinsics/simd.rs

@@ -577,11 +577,9 @@ pub unsafe fn simd_select<M, T>(mask: M, if_true: T, if_false: T) -> T;
 /// For each element, if the bit in `mask` is `1`, select the element from
 /// `if_true`.  If the corresponding bit in `mask` is `0`, select the element from
 /// `if_false`.
+/// The remaining bits of the mask are ignored.
 ///
 /// The bitmask bit order matches `simd_bitmask`.
-///
-/// # Safety
-/// Padding bits must be all zero.
 #[rustc_intrinsic]
 #[rustc_nounwind]
 pub unsafe fn simd_select_bitmask<M, T>(m: M, yes: T, no: T) -> T;

library/core/src/iter/traits/iterator.rs

@@ -1340,6 +1340,24 @@ pub trait Iterator {
     /// assert_eq!(iter.next(), Some(2));
     /// assert_eq!(iter.next(), None);
     /// ```
+    ///
+    /// Use [`by_ref`] to take from the iterator without consuming it, and then
+    /// continue using the original iterator:
+    ///
+    /// ```
+    /// let mut words = ["hello", "world", "of", "Rust"].into_iter();
+    ///
+    /// // Take the first two words.
+    /// let hello_world: Vec<_> = words.by_ref().take(2).collect();
+    /// assert_eq!(hello_world, vec!["hello", "world"]);
+    ///
+    /// // Collect the rest of the words.
+    /// // We can only do this because we used `by_ref` earlier.
+    /// let of_rust: Vec<_> = words.collect();
+    /// assert_eq!(of_rust, vec!["of", "Rust"]);
+    /// ```
+    ///
+    /// [`by_ref`]: Iterator::by_ref
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     fn take(self, n: usize) -> Take<Self>

library/core/src/macros/mod.rs

@@ -1748,8 +1748,8 @@ pub(crate) mod builtin {
         /* compiler built-in */
     }
 
-    /// Provide a list of type aliases and other opaque-type-containing type definitions.
-    /// This list will be used in the body of the item it is applied to define opaque
+    /// Provide a list of type aliases and other opaque-type-containing type definitions
+    /// to an item with a body. This list will be used in that body to define opaque
     /// types' hidden types.
     /// Can only be applied to things that have bodies.
     #[unstable(

library/core/src/num/diy_float.rs

@@ -21,61 +21,29 @@ pub struct Fp {
 
 impl Fp {
     /// Returns a correctly rounded product of itself and `other`.
-    pub fn mul(&self, other: &Fp) -> Fp {
-        const MASK: u64 = 0xffffffff;
-        let a = self.f >> 32;
-        let b = self.f & MASK;
-        let c = other.f >> 32;
-        let d = other.f & MASK;
-        let ac = a * c;
-        let bc = b * c;
-        let ad = a * d;
-        let bd = b * d;
-        let tmp = (bd >> 32) + (ad & MASK) + (bc & MASK) + (1 << 31) /* round */;
-        let f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32);
+    pub fn mul(self, other: Self) -> Self {
+        let (lo, hi) = self.f.widening_mul(other.f);
+        let f = hi + (lo >> 63) /* round */;
         let e = self.e + other.e + 64;
-        Fp { f, e }
+        Self { f, e }
     }
 
     /// Normalizes itself so that the resulting mantissa is at least `2^63`.
-    pub fn normalize(&self) -> Fp {
-        let mut f = self.f;
-        let mut e = self.e;
-        if f >> (64 - 32) == 0 {
-            f <<= 32;
-            e -= 32;
-        }
-        if f >> (64 - 16) == 0 {
-            f <<= 16;
-            e -= 16;
-        }
-        if f >> (64 - 8) == 0 {
-            f <<= 8;
-            e -= 8;
-        }
-        if f >> (64 - 4) == 0 {
-            f <<= 4;
-            e -= 4;
-        }
-        if f >> (64 - 2) == 0 {
-            f <<= 2;
-            e -= 2;
-        }
-        if f >> (64 - 1) == 0 {
-            f <<= 1;
-            e -= 1;
-        }
+    pub fn normalize(self) -> Self {
+        let lz = self.f.leading_zeros();
+        let f = self.f << lz;
+        let e = self.e - lz as i16;
         debug_assert!(f >= (1 << 63));
-        Fp { f, e }
+        Self { f, e }
     }
 
     /// Normalizes itself to have the shared exponent.
     /// It can only decrease the exponent (and thus increase the mantissa).
-    pub fn normalize_to(&self, e: i16) -> Fp {
+    pub fn normalize_to(self, e: i16) -> Self {
         let edelta = self.e - e;
         assert!(edelta >= 0);
         let edelta = edelta as usize;
         assert_eq!(self.f << edelta >> edelta, self.f);
-        Fp { f: self.f << edelta, e }
+        Self { f: self.f << edelta, e }
     }
 }

library/core/src/num/flt2dec/strategy/grisu.rs

@@ -196,9 +196,9 @@ pub fn format_shortest_opt<'a>(
     let (minusk, cached) = cached_power(ALPHA - plus.e - 64, GAMMA - plus.e - 64);
 
     // scale fps. this gives the maximal error of 1 ulp (proved from Theorem 5.1).
-    let plus = plus.mul(&cached);
-    let minus = minus.mul(&cached);
-    let v = v.mul(&cached);
+    let plus = plus.mul(cached);
+    let minus = minus.mul(cached);
+    let v = v.mul(cached);
     debug_assert_eq!(plus.e, minus.e);
     debug_assert_eq!(plus.e, v.e);
 
@@ -480,7 +480,7 @@ pub fn format_exact_opt<'a>(
     // normalize and scale `v`.
     let v = Fp { f: d.mant, e: d.exp }.normalize();
     let (minusk, cached) = cached_power(ALPHA - v.e - 64, GAMMA - v.e - 64);
-    let v = v.mul(&cached);
+    let v = v.mul(cached);
 
     // divide `v` into integral and fractional parts.
     let e = -v.e as usize;

library/std/src/fs.rs

@@ -21,14 +21,14 @@
 mod tests;
 
 use crate::ffi::OsString;
-use crate::fmt;
 use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write};
 use crate::path::{Path, PathBuf};
 use crate::sealed::Sealed;
 use crate::sync::Arc;
 use crate::sys::fs as fs_imp;
 use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
 use crate::time::SystemTime;
+use crate::{error, fmt};
 
 /// An object providing access to an open file on the filesystem.
 ///
@@ -116,6 +116,22 @@ pub struct File {
     inner: fs_imp::File,
 }
 
+/// An enumeration of possible errors which can occur while trying to acquire a lock
+/// from the [`try_lock`] method and [`try_lock_shared`] method on a [`File`].
+///
+/// [`try_lock`]: File::try_lock
+/// [`try_lock_shared`]: File::try_lock_shared
+#[unstable(feature = "file_lock", issue = "130994")]
+pub enum TryLockError {
+    /// The lock could not be acquired due to an I/O error on the file. The standard library will
+    /// not return an [`ErrorKind::WouldBlock`] error inside [`TryLockError::Error`]
+    ///
+    /// [`ErrorKind::WouldBlock`]: io::ErrorKind::WouldBlock
+    Error(io::Error),
+    /// The lock could not be acquired at this time because it is held by another handle/process.
+    WouldBlock,
+}
+
 /// Metadata information about a file.
 ///
 /// This structure is returned from the [`metadata`] or
@@ -352,6 +368,30 @@ pub fn write<P: AsRef<Path>, C: AsRef<[u8]>>(path: P, contents: C) -> io::Result
     inner(path.as_ref(), contents.as_ref())
 }
 
+#[unstable(feature = "file_lock", issue = "130994")]
+impl error::Error for TryLockError {}
+
+#[unstable(feature = "file_lock", issue = "130994")]
+impl fmt::Debug for TryLockError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            TryLockError::Error(err) => err.fmt(f),
+            TryLockError::WouldBlock => "WouldBlock".fmt(f),
+        }
+    }
+}
+
+#[unstable(feature = "file_lock", issue = "130994")]
+impl fmt::Display for TryLockError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            TryLockError::Error(_) => "lock acquisition failed due to I/O error",
+            TryLockError::WouldBlock => "lock acquisition failed because the operation would block",
+        }
+        .fmt(f)
+    }
+}
+
 impl File {
     /// Attempts to open a file in read-only mode.
     ///
@@ -734,8 +774,8 @@ impl File {
 
     /// Try to acquire an exclusive lock on the file.
     ///
-    /// Returns `Ok(false)` if a different lock is already held on this file (via another
-    /// handle/descriptor).
+    /// Returns `Err(TryLockError::WouldBlock)` if a different lock is already held on this file
+    /// (via another handle/descriptor).
     ///
     /// This acquires an exclusive lock; no other file handle to this file may acquire another lock.
     ///
@@ -777,23 +817,27 @@ impl File {
     ///
     /// ```no_run
     /// #![feature(file_lock)]
-    /// use std::fs::File;
+    /// use std::fs::{File, TryLockError};
     ///
     /// fn main() -> std::io::Result<()> {
     ///     let f = File::create("foo.txt")?;
-    ///     f.try_lock()?;
+    ///     match f.try_lock() {
+    ///         Ok(_) => (),
+    ///         Err(TryLockError::WouldBlock) => (), // Lock not acquired
+    ///         Err(TryLockError::Error(err)) => return Err(err),
+    ///     }
     ///     Ok(())
     /// }
     /// ```
     #[unstable(feature = "file_lock", issue = "130994")]
-    pub fn try_lock(&self) -> io::Result<bool> {
+    pub fn try_lock(&self) -> Result<(), TryLockError> {
         self.inner.try_lock()
     }
 
     /// Try to acquire a shared (non-exclusive) lock on the file.
     ///
-    /// Returns `Ok(false)` if an exclusive lock is already held on this file (via another
-    /// handle/descriptor).
+    /// Returns `Err(TryLockError::WouldBlock)` if a different lock is already held on this file
+    /// (via another handle/descriptor).
     ///
     /// This acquires a shared lock; more than one file handle may hold a shared lock, but none may
     /// hold an exclusive lock at the same time.
@@ -834,16 +878,21 @@ impl File {
     ///
     /// ```no_run
     /// #![feature(file_lock)]
-    /// use std::fs::File;
+    /// use std::fs::{File, TryLockError};
     ///
     /// fn main() -> std::io::Result<()> {
     ///     let f = File::open("foo.txt")?;
-    ///     f.try_lock_shared()?;
+    ///     match f.try_lock_shared() {
+    ///         Ok(_) => (),
+    ///         Err(TryLockError::WouldBlock) => (), // Lock not acquired
+    ///         Err(TryLockError::Error(err)) => return Err(err),
+    ///     }
+    ///
     ///     Ok(())
     /// }
     /// ```
     #[unstable(feature = "file_lock", issue = "130994")]
-    pub fn try_lock_shared(&self) -> io::Result<bool> {
+    pub fn try_lock_shared(&self) -> Result<(), TryLockError> {
         self.inner.try_lock_shared()
     }
 
@@ -2874,6 +2923,8 @@ pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 ///
 /// Consider ignoring the error if validating the removal is not required for your use case.
 ///
+/// This function may return [`io::ErrorKind::DirectoryNotEmpty`] if the directory is concurrently
+/// written into, which typically indicates some contents were removed but not all.
 /// [`io::ErrorKind::NotFound`] is only returned if no removal occurs.
 ///
 /// [`fs::remove_file`]: remove_file