library: Use size_of from the prelude instead of imported

Use `std::mem::{size_of, size_of_val, align_of, align_of_val}` from the
prelude instead of importing or qualifying them.

These functions were added to all preludes in Rust 1.80.

library/alloc/benches/slice.rs

@@ -1,4 +1,4 @@
-use std::{mem, ptr};
+use std::ptr;
 
 use rand::Rng;
 use rand::distr::{Alphanumeric, SampleString, StandardUniform};
@@ -234,7 +234,7 @@ macro_rules! sort {
         fn $name(b: &mut Bencher) {
             let v = $gen($len);
             b.iter(|| v.clone().$f());
-            b.bytes = $len * mem::size_of_val(&$gen(1)[0]) as u64;
+            b.bytes = $len * size_of_val(&$gen(1)[0]) as u64;
         }
     };
 }
@@ -246,7 +246,7 @@ macro_rules! sort_strings {
             let v = $gen($len);
             let v = v.iter().map(|s| &**s).collect::<Vec<&str>>();
             b.iter(|| v.clone().$f());
-            b.bytes = $len * mem::size_of::<&str>() as u64;
+            b.bytes = $len * size_of::<&str>() as u64;
         }
     };
 }
@@ -268,7 +268,7 @@ macro_rules! sort_expensive {
                 });
                 black_box(count);
             });
-            b.bytes = $len * mem::size_of_val(&$gen(1)[0]) as u64;
+            b.bytes = $len * size_of_val(&$gen(1)[0]) as u64;
         }
     };
 }
@@ -279,7 +279,7 @@ macro_rules! sort_lexicographic {
         fn $name(b: &mut Bencher) {
             let v = $gen($len);
             b.iter(|| v.clone().$f(|x| x.to_string()));
-            b.bytes = $len * mem::size_of_val(&$gen(1)[0]) as u64;
+            b.bytes = $len * size_of_val(&$gen(1)[0]) as u64;
         }
     };
 }
@@ -322,7 +322,7 @@ macro_rules! reverse {
         fn $name(b: &mut Bencher) {
             // odd length and offset by 1 to be as unaligned as possible
             let n = 0xFFFFF;
-            let mut v: Vec<_> = (0..1 + (n / mem::size_of::<$ty>() as u64)).map($f).collect();
+            let mut v: Vec<_> = (0..1 + (n / size_of::<$ty>() as u64)).map($f).collect();
             b.iter(|| black_box(&mut v[1..]).reverse());
             b.bytes = n;
         }
@@ -346,7 +346,7 @@ macro_rules! rotate {
     ($name:ident, $gen:expr, $len:expr, $mid:expr) => {
         #[bench]
         fn $name(b: &mut Bencher) {
-            let size = mem::size_of_val(&$gen(1)[0]);
+            let size = size_of_val(&$gen(1)[0]);
             let mut v = $gen($len * 8 / size);
             b.iter(|| black_box(&mut v).rotate_left(($mid * 8 + size - 1) / size));
             b.bytes = (v.len() * size) as u64;

library/alloc/benches/vec.rs

@@ -669,7 +669,7 @@ fn random_sorted_fill(mut seed: u32, buf: &mut [u32]) {
 // This algorithm was used for Vecs prior to Rust 1.52.
 fn bench_dedup_slice_truncate(b: &mut Bencher, sz: usize) {
     let mut template = vec![0u32; sz];
-    b.bytes = std::mem::size_of_val(template.as_slice()) as u64;
+    b.bytes = size_of_val(template.as_slice()) as u64;
     random_sorted_fill(0x43, &mut template);
 
     let mut vec = template.clone();
@@ -691,7 +691,7 @@ fn bench_dedup_slice_truncate(b: &mut Bencher, sz: usize) {
 // Measures performance of Vec::dedup on random data.
 fn bench_vec_dedup_random(b: &mut Bencher, sz: usize) {
     let mut template = vec![0u32; sz];
-    b.bytes = std::mem::size_of_val(template.as_slice()) as u64;
+    b.bytes = size_of_val(template.as_slice()) as u64;
     random_sorted_fill(0x43, &mut template);
 
     let mut vec = template.clone();
@@ -708,7 +708,7 @@ fn bench_vec_dedup_random(b: &mut Bencher, sz: usize) {
 // Measures performance of Vec::dedup when there is no items removed
 fn bench_vec_dedup_none(b: &mut Bencher, sz: usize) {
     let mut template = vec![0u32; sz];
-    b.bytes = std::mem::size_of_val(template.as_slice()) as u64;
+    b.bytes = size_of_val(template.as_slice()) as u64;
     template.chunks_exact_mut(2).for_each(|w| {
         w[0] = black_box(0);
         w[1] = black_box(5);
@@ -729,7 +729,7 @@ fn bench_vec_dedup_none(b: &mut Bencher, sz: usize) {
 // Measures performance of Vec::dedup when there is all items removed
 fn bench_vec_dedup_all(b: &mut Bencher, sz: usize) {
     let mut template = vec![0u32; sz];
-    b.bytes = std::mem::size_of_val(template.as_slice()) as u64;
+    b.bytes = size_of_val(template.as_slice()) as u64;
     template.iter_mut().for_each(|w| {
         *w = black_box(0);
     });

library/alloc/src/boxed/convert.rs

@@ -529,7 +529,6 @@ impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
     /// ```
     /// use std::error::Error;
     /// use std::fmt;
-    /// use std::mem;
     ///
     /// #[derive(Debug)]
     /// struct AnError;
@@ -543,9 +542,9 @@ impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
     /// impl Error for AnError {}
     ///
     /// let an_error = AnError;
-    /// assert!(0 == mem::size_of_val(&an_error));
+    /// assert!(0 == size_of_val(&an_error));
     /// let a_boxed_error = Box::<dyn Error>::from(an_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
+    /// assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))
     /// ```
     fn from(err: E) -> Box<dyn Error + 'a> {
         Box::new(err)
@@ -563,7 +562,6 @@ impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync +
     /// ```
     /// use std::error::Error;
     /// use std::fmt;
-    /// use std::mem;
     ///
     /// #[derive(Debug)]
     /// struct AnError;
@@ -581,10 +579,10 @@ impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync +
     /// unsafe impl Sync for AnError {}
     ///
     /// let an_error = AnError;
-    /// assert!(0 == mem::size_of_val(&an_error));
+    /// assert!(0 == size_of_val(&an_error));
     /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(an_error);
     /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
+    ///     size_of::<Box<dyn Error + Send + Sync>>() == size_of_val(&a_boxed_error))
     /// ```
     fn from(err: E) -> Box<dyn Error + Send + Sync + 'a> {
         Box::new(err)
@@ -600,12 +598,11 @@ impl<'a> From<String> for Box<dyn Error + Send + Sync + 'a> {
     ///
     /// ```
     /// use std::error::Error;
-    /// use std::mem;
     ///
     /// let a_string_error = "a string error".to_string();
     /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error);
     /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
+    ///     size_of::<Box<dyn Error + Send + Sync>>() == size_of_val(&a_boxed_error))
     /// ```
     #[inline]
     fn from(err: String) -> Box<dyn Error + Send + Sync + 'a> {
@@ -644,11 +641,10 @@ impl<'a> From<String> for Box<dyn Error + 'a> {
     ///
     /// ```
     /// use std::error::Error;
-    /// use std::mem;
     ///
     /// let a_string_error = "a string error".to_string();
     /// let a_boxed_error = Box::<dyn Error>::from(a_string_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
+    /// assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))
     /// ```
     fn from(str_err: String) -> Box<dyn Error + 'a> {
         let err1: Box<dyn Error + Send + Sync> = From::from(str_err);
@@ -668,12 +664,11 @@ impl<'a> From<&str> for Box<dyn Error + Send + Sync + 'a> {
     ///
     /// ```
     /// use std::error::Error;
-    /// use std::mem;
     ///
     /// let a_str_error = "a str error";
     /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_str_error);
     /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
+    ///     size_of::<Box<dyn Error + Send + Sync>>() == size_of_val(&a_boxed_error))
     /// ```
     #[inline]
     fn from(err: &str) -> Box<dyn Error + Send + Sync + 'a> {
@@ -692,11 +687,10 @@ impl<'a> From<&str> for Box<dyn Error + 'a> {
     ///
     /// ```
     /// use std::error::Error;
-    /// use std::mem;
     ///
     /// let a_str_error = "a str error";
     /// let a_boxed_error = Box::<dyn Error>::from(a_str_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
+    /// assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))
     /// ```
     fn from(err: &str) -> Box<dyn Error + 'a> {
         From::from(String::from(err))
@@ -712,13 +706,12 @@ impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a> {
     ///
     /// ```
     /// use std::error::Error;
-    /// use std::mem;
     /// use std::borrow::Cow;
     ///
     /// let a_cow_str_error = Cow::from("a str error");
     /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_cow_str_error);
     /// assert!(
-    ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
+    ///     size_of::<Box<dyn Error + Send + Sync>>() == size_of_val(&a_boxed_error))
     /// ```
     fn from(err: Cow<'b, str>) -> Box<dyn Error + Send + Sync + 'a> {
         From::from(String::from(err))
@@ -734,12 +727,11 @@ impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + 'a> {
     ///
     /// ```
     /// use std::error::Error;
-    /// use std::mem;
     /// use std::borrow::Cow;
     ///
     /// let a_cow_str_error = Cow::from("a str error");
     /// let a_boxed_error = Box::<dyn Error>::from(a_cow_str_error);
-    /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
+    /// assert!(size_of::<Box<dyn Error>>() == size_of_val(&a_boxed_error))
     /// ```
     fn from(err: Cow<'b, str>) -> Box<dyn Error + 'a> {
         From::from(String::from(err))

library/alloc/src/boxed/thin.rs

@@ -9,9 +9,8 @@ use core::intrinsics::const_allocate;
 use core::marker::PhantomData;
 #[cfg(not(no_global_oom_handling))]
 use core::marker::Unsize;
-use core::mem;
 #[cfg(not(no_global_oom_handling))]
-use core::mem::SizedTypeProperties;
+use core::mem::{self, SizedTypeProperties};
 use core::ops::{Deref, DerefMut};
 use core::ptr::{self, NonNull, Pointee};
 
@@ -30,7 +29,6 @@ use crate::alloc::{self, Layout, LayoutError};
 /// let five = ThinBox::new(5);
 /// let thin_slice = ThinBox::<[i32]>::new_unsize([1, 2, 3, 4]);
 ///
-/// use std::mem::{size_of, size_of_val};
 /// let size_of_ptr = size_of::<*const ()>();
 /// assert_eq!(size_of_ptr, size_of_val(&five));
 /// assert_eq!(size_of_ptr, size_of_val(&thin_slice));
@@ -114,7 +112,7 @@ impl<Dyn: ?Sized> ThinBox<Dyn> {
     where
         T: Unsize<Dyn>,
     {
-        if mem::size_of::<T>() == 0 {
+        if size_of::<T>() == 0 {
             let ptr = WithOpaqueHeader::new_unsize_zst::<Dyn, T>(value);
             ThinBox { ptr, _marker: PhantomData }
         } else {
@@ -283,9 +281,7 @@ impl<H> WithHeader<H> {
             let ptr = if layout.size() == 0 {
                 // Some paranoia checking, mostly so that the ThinBox tests are
                 // more able to catch issues.
-                debug_assert!(
-                    value_offset == 0 && mem::size_of::<T>() == 0 && mem::size_of::<H>() == 0
-                );
+                debug_assert!(value_offset == 0 && size_of::<T>() == 0 && size_of::<H>() == 0);
                 layout.dangling()
             } else {
                 let ptr = alloc::alloc(layout);
@@ -315,7 +311,7 @@ impl<H> WithHeader<H> {
         Dyn: Pointee<Metadata = H> + ?Sized,
         T: Unsize<Dyn>,
     {
-        assert!(mem::size_of::<T>() == 0);
+        assert!(size_of::<T>() == 0);
 
         const fn max(a: usize, b: usize) -> usize {
             if a > b { a } else { b }
@@ -329,18 +325,16 @@ impl<H> WithHeader<H> {
             // FIXME: just call `WithHeader::alloc_layout` with size reset to 0.
             // Currently that's blocked on `Layout::extend` not being `const fn`.
 
-            let alloc_align =
-                max(mem::align_of::<T>(), mem::align_of::<<Dyn as Pointee>::Metadata>());
+            let alloc_align = max(align_of::<T>(), align_of::<<Dyn as Pointee>::Metadata>());
 
-            let alloc_size =
-                max(mem::align_of::<T>(), mem::size_of::<<Dyn as Pointee>::Metadata>());
+            let alloc_size = max(align_of::<T>(), size_of::<<Dyn as Pointee>::Metadata>());
 
             unsafe {
                 // SAFETY: align is power of two because it is the maximum of two alignments.
                 let alloc: *mut u8 = const_allocate(alloc_size, alloc_align);
 
                 let metadata_offset =
-                    alloc_size.checked_sub(mem::size_of::<<Dyn as Pointee>::Metadata>()).unwrap();
+                    alloc_size.checked_sub(size_of::<<Dyn as Pointee>::Metadata>()).unwrap();
                 // SAFETY: adding offset within the allocation.
                 let metadata_ptr: *mut <Dyn as Pointee>::Metadata =
                     alloc.add(metadata_offset).cast();
@@ -421,7 +415,7 @@ impl<H> WithHeader<H> {
     }
 
     const fn header_size() -> usize {
-        mem::size_of::<H>()
+        size_of::<H>()
     }
 
     fn alloc_layout(value_layout: Layout) -> Result<(Layout, usize), LayoutError> {

library/alloc/src/collections/btree/node/tests.rs

@@ -92,8 +92,8 @@ fn test_partial_eq() {
 #[cfg(target_arch = "x86_64")]
 #[cfg_attr(any(miri, randomized_layouts), ignore)] // We'd like to run Miri with layout randomization
 fn test_sizes() {
-    assert_eq!(core::mem::size_of::<LeafNode<(), ()>>(), 16);
-    assert_eq!(core::mem::size_of::<LeafNode<i64, i64>>(), 16 + CAPACITY * 2 * 8);
-    assert_eq!(core::mem::size_of::<InternalNode<(), ()>>(), 16 + (CAPACITY + 1) * 8);
-    assert_eq!(core::mem::size_of::<InternalNode<i64, i64>>(), 16 + (CAPACITY * 3 + 1) * 8);
+    assert_eq!(size_of::<LeafNode<(), ()>>(), 16);
+    assert_eq!(size_of::<LeafNode<i64, i64>>(), 16 + CAPACITY * 2 * 8);
+    assert_eq!(size_of::<InternalNode<(), ()>>(), 16 + (CAPACITY + 1) * 8);
+    assert_eq!(size_of::<InternalNode<i64, i64>>(), 16 + (CAPACITY * 3 + 1) * 8);
 }

library/alloc/src/raw_vec.rs

@@ -480,7 +480,7 @@ impl<A: Allocator> RawVecInner<A> {
 
         // Allocators currently return a `NonNull<[u8]>` whose length
         // matches the size requested. If that ever changes, the capacity
-        // here should change to `ptr.len() / mem::size_of::<T>()`.
+        // here should change to `ptr.len() / size_of::<T>()`.
         Ok(Self {
             ptr: Unique::from(ptr.cast()),
             cap: unsafe { Cap::new_unchecked(capacity) },
@@ -627,7 +627,7 @@ impl<A: Allocator> RawVecInner<A> {
     unsafe fn set_ptr_and_cap(&mut self, ptr: NonNull<[u8]>, cap: usize) {
         // Allocators currently return a `NonNull<[u8]>` whose length matches
         // the size requested. If that ever changes, the capacity here should
-        // change to `ptr.len() / mem::size_of::<T>()`.
+        // change to `ptr.len() / size_of::<T>()`.
         self.ptr = Unique::from(ptr.cast());
         self.cap = unsafe { Cap::new_unchecked(cap) };
     }

library/alloc/src/raw_vec/tests.rs

@@ -1,4 +1,3 @@
-use core::mem::size_of;
 use std::cell::Cell;
 
 use super::*;
@@ -93,7 +92,7 @@ fn zst_sanity<T>(v: &RawVec<T>) {
 fn zst() {
     let cap_err = Err(crate::collections::TryReserveErrorKind::CapacityOverflow.into());
 
-    assert_eq!(std::mem::size_of::<ZST>(), 0);
+    assert_eq!(size_of::<ZST>(), 0);
 
     // All these different ways of creating the RawVec produce the same thing.
 

library/alloc/src/slice.rs

@@ -16,7 +16,7 @@ use core::borrow::{Borrow, BorrowMut};
 #[cfg(not(no_global_oom_handling))]
 use core::cmp::Ordering::{self, Less};
 #[cfg(not(no_global_oom_handling))]
-use core::mem::{self, MaybeUninit};
+use core::mem::MaybeUninit;
 #[cfg(not(no_global_oom_handling))]
 use core::ptr;
 #[unstable(feature = "array_chunks", issue = "74985")]
@@ -446,7 +446,7 @@ impl<T> [T] {
         // Avoids binary-size usage in cases where the alignment doesn't work out to make this
         // beneficial or on 32-bit platforms.
         let is_using_u32_as_idx_type_helpful =
-            const { mem::size_of::<(K, u32)>() < mem::size_of::<(K, usize)>() };
+            const { size_of::<(K, u32)>() < size_of::<(K, usize)>() };
 
         // It's possible to instantiate this for u8 and u16 but, doing so is very wasteful in terms
         // of compile-times and binary-size, the peak saved heap memory for u16 is (u8 + u16) -> 4

library/alloc/src/string.rs

@@ -119,16 +119,14 @@ use crate::vec::{self, Vec};
 /// the same `char`s:
 ///
 /// ```
-/// use std::mem;
-///
 /// // `s` is ASCII which represents each `char` as one byte
 /// let s = "hello";
 /// assert_eq!(s.len(), 5);
 ///
 /// // A `char` array with the same contents would be longer because
 /// // every `char` is four bytes
 /// let s = ['h', 'e', 'l', 'l', 'o'];
-/// let size: usize = s.into_iter().map(|c| mem::size_of_val(&c)).sum();
+/// let size: usize = s.into_iter().map(|c| size_of_val(&c)).sum();
 /// assert_eq!(size, 20);
 ///
 /// // However, for non-ASCII strings, the difference will be smaller
@@ -137,7 +135,7 @@ use crate::vec::{self, Vec};
 /// assert_eq!(s.len(), 20);
 ///
 /// let s = ['💖', '💖', '💖', '💖', '💖'];
-/// let size: usize = s.into_iter().map(|c| mem::size_of_val(&c)).sum();
+/// let size: usize = s.into_iter().map(|c| size_of_val(&c)).sum();
 /// assert_eq!(size, 20);
 /// ```
 ///