Auto merge of #83199 - JohnTitor:rollup-zrfk94a, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - #81822 (Added `try_exists()` method to `std::path::Path`)
 - #83072 (Update `Vec` docs)
 - #83077 (rustdoc: reduce GC work during search)
 - #83091 (Constify `copy` related functions)
 - #83156 (Fall-back to sans-serif if Arial is not available)
 - #83157 (No background for code in portability snippets)
 - #83160 (Deprecate RustcEncodable and RustcDecodable.)
 - #83162 (Specify *.woff2 files as binary)
 - #83172 (More informative diagnotic from `x.py test` attempt atop beta checkout)
 - #83196 (Use delay_span_bug instead of panic in layout_scalar_valid_range)

Failed merges:

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

Author: bors

.gitattributes

@@ -8,6 +8,7 @@
 *.mir linguist-language=Rust
 src/etc/installer/gfx/* binary
 *.woff binary
+*.woff2 binary
 src/vendor/** -text
 Cargo.lock linguist-generated=false
 

compiler/rustc_middle/src/ty/context.rs

@@ -1091,13 +1091,16 @@ impl<'tcx> TyCtxt<'tcx> {
                 None => return Bound::Unbounded,
             };
             debug!("layout_scalar_valid_range: attr={:?}", attr);
-            for meta in attr.meta_item_list().expect("rustc_layout_scalar_valid_range takes args") {
-                match meta.literal().expect("attribute takes lit").kind {
-                    ast::LitKind::Int(a, _) => return Bound::Included(a),
-                    _ => span_bug!(attr.span, "rustc_layout_scalar_valid_range expects int arg"),
-                }
+            if let Some(
+                &[ast::NestedMetaItem::Literal(ast::Lit { kind: ast::LitKind::Int(a, _), .. })],
+            ) = attr.meta_item_list().as_deref()
+            {
+                Bound::Included(a)
+            } else {
+                self.sess
+                    .delay_span_bug(attr.span, "invalid rustc_layout_scalar_valid_range attribute");
+                Bound::Unbounded
             }
-            span_bug!(attr.span, "no arguments to `rustc_layout_scalar_valid_range` attribute");
         };
         (
             get(sym::rustc_layout_scalar_valid_range_start),

library/alloc/src/vec/mod.rs

@@ -126,7 +126,7 @@ use self::spec_extend::SpecExtend;
 
 mod spec_extend;
 
-/// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
+/// A contiguous growable array type, written as `Vec<T>` and pronounced 'vector'.
 ///
 /// # Examples
 ///
@@ -215,7 +215,7 @@ mod spec_extend;
 ///
 /// # Slicing
 ///
-/// A `Vec` can be mutable. Slices, on the other hand, are read-only objects.
+/// A `Vec` can be mutable. On the other hand, slices are read-only objects.
 /// To get a [slice][prim@slice], use [`&`]. Example:
 ///
 /// ```
@@ -352,7 +352,7 @@ mod spec_extend;
 /// not break, however: using `unsafe` code to write to the excess capacity,
 /// and then increasing the length to match, is always valid.
 ///
-/// `Vec` does not currently guarantee the order in which elements are dropped.
+/// Currently, `Vec` does not guarantee the order in which elements are dropped.
 /// The order has changed in the past and may change again.
 ///
 /// [`get`]: ../../std/vec/struct.Vec.html#method.get

library/core/src/intrinsics.rs

@@ -1902,18 +1902,6 @@ pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool {
     !ptr.is_null() && ptr as usize % mem::align_of::<T>() == 0
 }
 
-/// Checks whether the regions of memory starting at `src` and `dst` of size
-/// `count * size_of::<T>()` do *not* overlap.
-pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -> bool {
-    let src_usize = src as usize;
-    let dst_usize = dst as usize;
-    let size = mem::size_of::<T>().checked_mul(count).unwrap();
-    let diff = if src_usize > dst_usize { src_usize - dst_usize } else { dst_usize - src_usize };
-    // If the absolute distance between the ptrs is at least as big as the size of the buffer,
-    // they do not overlap.
-    diff >= size
-}
-
 /// Sets `count * size_of::<T>()` bytes of memory starting at `dst` to
 /// `val`.
 ///

library/core/src/lib.rs

@@ -98,6 +98,7 @@
 #![feature(const_slice_from_raw_parts)]
 #![feature(const_slice_ptr_len)]
 #![feature(const_size_of_val)]
+#![feature(const_swap)]
 #![feature(const_align_of_val)]
 #![feature(const_type_id)]
 #![feature(const_type_name)]

library/core/src/macros/mod.rs

@@ -1468,6 +1468,10 @@ pub(crate) mod builtin {
     #[rustc_builtin_macro]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[allow_internal_unstable(core_intrinsics, libstd_sys_internals)]
+    #[rustc_deprecated(
+        since = "1.52.0",
+        reason = "rustc-serialize is deprecated and no longer supported"
+    )]
     pub macro RustcDecodable($item:item) {
         /* compiler built-in */
     }
@@ -1476,6 +1480,10 @@ pub(crate) mod builtin {
     #[rustc_builtin_macro]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[allow_internal_unstable(core_intrinsics)]
+    #[rustc_deprecated(
+        since = "1.52.0",
+        reason = "rustc-serialize is deprecated and no longer supported"
+    )]
     pub macro RustcEncodable($item:item) {
         /* compiler built-in */
     }

library/core/src/mem/mod.rs

@@ -682,7 +682,8 @@ pub unsafe fn uninitialized<T>() -> T {
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub fn swap<T>(x: &mut T, y: &mut T) {
+#[rustc_const_unstable(feature = "const_swap", issue = "83163")]
+pub const fn swap<T>(x: &mut T, y: &mut T) {
     // SAFETY: the raw pointers have been created from safe mutable references satisfying all the
     // constraints on `ptr::swap_nonoverlapping_one`
     unsafe {
@@ -812,7 +813,8 @@ pub fn take<T: Default>(dest: &mut T) -> T {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[must_use = "if you don't need the old value, you can just assign the new value directly"]
-pub fn replace<T>(dest: &mut T, src: T) -> T {
+#[rustc_const_unstable(feature = "const_replace", issue = "83164")]
+pub const fn replace<T>(dest: &mut T, src: T) -> T {
     // SAFETY: We read from `dest` but directly write `src` into it afterwards,
     // such that the old value is not duplicated. Nothing is dropped and
     // nothing here can panic.
@@ -931,7 +933,8 @@ pub fn drop<T>(_x: T) {}
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub unsafe fn transmute_copy<T, U>(src: &T) -> U {
+#[rustc_const_unstable(feature = "const_transmute_copy", issue = "83165")]
+pub const unsafe fn transmute_copy<T, U>(src: &T) -> U {
     // If U has a higher alignment requirement, src may not be suitably aligned.
     if align_of::<U>() > align_of::<T>() {
         // SAFETY: `src` is a reference which is guaranteed to be valid for reads.

library/core/src/prelude/v1.rs

@@ -61,7 +61,7 @@ pub use crate::{
 };
 
 #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
-#[allow(deprecated)]
+#[allow(deprecated, deprecated_in_future)]
 #[doc(no_inline)]
 pub use crate::macros::builtin::{
     bench, global_allocator, test, test_case, RustcDecodable, RustcEncodable,

library/core/src/ptr/const_ptr.rs

@@ -819,9 +819,10 @@ impl<T: ?Sized> *const T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
+    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
-    pub unsafe fn copy_to(self, dest: *mut T, count: usize)
+    pub const unsafe fn copy_to(self, dest: *mut T, count: usize)
     where
         T: Sized,
     {
@@ -837,9 +838,10 @@ impl<T: ?Sized> *const T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
+    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
-    pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
+    pub const unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
     where
         T: Sized,
     {

library/core/src/ptr/mod.rs

@@ -67,7 +67,7 @@
 use crate::cmp::Ordering;
 use crate::fmt;
 use crate::hash;
-use crate::intrinsics::{self, abort, is_aligned_and_not_null, is_nonoverlapping};
+use crate::intrinsics::{self, abort, is_aligned_and_not_null};
 use crate::mem::{self, MaybeUninit};
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -394,7 +394,8 @@ pub const fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T] {
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub unsafe fn swap<T>(x: *mut T, y: *mut T) {
+#[rustc_const_unstable(feature = "const_swap", issue = "83163")]
+pub const unsafe fn swap<T>(x: *mut T, y: *mut T) {
     // Give ourselves some scratch space to work with.
     // We do not have to worry about drops: `MaybeUninit` does nothing when dropped.
     let mut tmp = MaybeUninit::<T>::uninit();
@@ -451,16 +452,8 @@ pub unsafe fn swap<T>(x: *mut T, y: *mut T) {
 /// ```
 #[inline]
 #[stable(feature = "swap_nonoverlapping", since = "1.27.0")]
-pub unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
-    if cfg!(debug_assertions)
-        && !(is_aligned_and_not_null(x)
-            && is_aligned_and_not_null(y)
-            && is_nonoverlapping(x, y, count))
-    {
-        // Not panicking to keep codegen impact smaller.
-        abort();
-    }
-
+#[rustc_const_unstable(feature = "const_swap", issue = "83163")]
+pub const unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
     let x = x as *mut u8;
     let y = y as *mut u8;
     let len = mem::size_of::<T>() * count;
@@ -470,7 +463,8 @@ pub unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
 }
 
 #[inline]
-pub(crate) unsafe fn swap_nonoverlapping_one<T>(x: *mut T, y: *mut T) {
+#[rustc_const_unstable(feature = "const_swap", issue = "83163")]
+pub(crate) const unsafe fn swap_nonoverlapping_one<T>(x: *mut T, y: *mut T) {
     // For types smaller than the block optimization below,
     // just swap directly to avoid pessimizing codegen.
     if mem::size_of::<T>() < 32 {
@@ -488,7 +482,8 @@ pub(crate) unsafe fn swap_nonoverlapping_one<T>(x: *mut T, y: *mut T) {
 }
 
 #[inline]
-unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) {
+#[rustc_const_unstable(feature = "const_swap", issue = "83163")]
+const unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) {
     // The approach here is to utilize simd to swap x & y efficiently. Testing reveals
     // that swapping either 32 bytes or 64 bytes at a time is most efficient for Intel
     // Haswell E processors. LLVM is more able to optimize if we give a struct a
@@ -589,7 +584,8 @@ unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) {
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
+#[rustc_const_unstable(feature = "const_replace", issue = "83164")]
+pub const unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
     // SAFETY: the caller must guarantee that `dst` is valid to be
     // cast to a mutable reference (valid for writes, aligned, initialized),
     // and cannot overlap `src` since `dst` must point to a distinct

library/core/src/ptr/mut_ptr.rs

@@ -926,9 +926,10 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
+    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
-    pub unsafe fn copy_to(self, dest: *mut T, count: usize)
+    pub const unsafe fn copy_to(self, dest: *mut T, count: usize)
     where
         T: Sized,
     {
@@ -944,9 +945,10 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
+    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
-    pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
+    pub const unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
     where
         T: Sized,
     {
@@ -962,9 +964,10 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
+    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
-    pub unsafe fn copy_from(self, src: *const T, count: usize)
+    pub const unsafe fn copy_from(self, src: *const T, count: usize)
     where
         T: Sized,
     {
@@ -980,9 +983,10 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
+    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
-    pub unsafe fn copy_from_nonoverlapping(self, src: *const T, count: usize)
+    pub const unsafe fn copy_from_nonoverlapping(self, src: *const T, count: usize)
     where
         T: Sized,
     {

library/std/src/path.rs

@@ -2472,6 +2472,36 @@ impl Path {
         fs::metadata(self).is_ok()
     }
 
+    /// Returns `Ok(true)` if the path points at an existing entity.
+    ///
+    /// This function will traverse symbolic links to query information about the
+    /// destination file. In case of broken symbolic links this will return `Ok(false)`.
+    ///
+    /// As opposed to the `exists()` method, this one doesn't silently ignore errors
+    /// unrelated to the path not existing. (E.g. it will return `Err(_)` in case of permission
+    /// denied on some of the parent directories.)
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(path_try_exists)]
+    ///
+    /// use std::path::Path;
+    /// assert!(!Path::new("does_not_exist.txt").try_exists().expect("Can't check existence of file does_not_exist.txt"));
+    /// assert!(Path::new("/root/secret_file.txt").try_exists().is_err());
+    /// ```
+    // FIXME: stabilization should modify documentation of `exists()` to recommend this method
+    // instead.
+    #[unstable(feature = "path_try_exists", issue = "83186")]
+    #[inline]
+    pub fn try_exists(&self) -> io::Result<bool> {
+        match fs::metadata(self) {
+            Ok(_) => Ok(true),
+            Err(error) if error.kind() == io::ErrorKind::NotFound => Ok(false),
+            Err(error) => Err(error),
+        }
+    }
+
     /// Returns `true` if the path exists on disk and is pointing at a regular file.
     ///
     /// This function will traverse symbolic links to query information about the

library/std/src/prelude/v1.rs

@@ -48,7 +48,7 @@ pub use core::prelude::v1::{
 // FIXME: Attribute and internal derive macros are not documented because for them rustdoc generates
 // dead links which fail link checker testing.
 #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
-#[allow(deprecated)]
+#[allow(deprecated, deprecated_in_future)]
 #[doc(hidden)]
 pub use core::prelude::v1::{
     bench, global_allocator, test, test_case, RustcDecodable, RustcEncodable,

src/bootstrap/test.rs

@@ -791,6 +791,19 @@ impl Step for Tidy {
 
         if builder.config.channel == "dev" || builder.config.channel == "nightly" {
             builder.info("fmt check");
+            if builder.config.initial_rustfmt.is_none() {
+                let inferred_rustfmt_dir = builder.config.initial_rustc.parent().unwrap();
+                eprintln!(
+                    "\
+error: no `rustfmt` binary found in {PATH}
+info: `rust.channel` is currently set to \"{CHAN}\"
+help: if you are testing a beta branch, set `rust.channel` to \"beta\" in the `config.toml` file
+help: to skip test's attempt to check tidiness, pass `--exclude src/tools/tidy` to `x.py test`",
+                    PATH = inferred_rustfmt_dir.display(),
+                    CHAN = builder.config.channel,
+                );
+                std::process::exit(1);
+            }
             crate::format::format(&builder.build, !builder.config.cmd.bless());
         }
     }