Rollup merge of rust-lang#138040 - thaliaarchi:use-prelude-size-of.compiler, r=compiler-errors

compiler: 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. Apply this change across the compiler.

These functions were added to all preludes in Rust 1.80.

r? ``@compiler-errors``

Author: matthiaskrgr

compiler/rustc_arena/src/lib.rs

@@ -93,7 +93,7 @@ impl<T> ArenaChunk<T> {
     #[inline]
     fn end(&mut self) -> *mut T {
         unsafe {
-            if mem::size_of::<T>() == 0 {
+            if size_of::<T>() == 0 {
                 // A pointer as large as possible for zero-sized elements.
                 ptr::without_provenance_mut(!0)
             } else {
@@ -151,7 +151,7 @@ impl<T> TypedArena<T> {
         }
 
         unsafe {
-            if mem::size_of::<T>() == 0 {
+            if size_of::<T>() == 0 {
                 self.ptr.set(self.ptr.get().wrapping_byte_add(1));
                 let ptr = ptr::NonNull::<T>::dangling().as_ptr();
                 // Don't drop the object. This `write` is equivalent to `forget`.
@@ -173,13 +173,13 @@ impl<T> TypedArena<T> {
         // FIXME: this should *likely* use `offset_from`, but more
         // investigation is needed (including running tests in miri).
         let available_bytes = self.end.get().addr() - self.ptr.get().addr();
-        let additional_bytes = additional.checked_mul(mem::size_of::<T>()).unwrap();
+        let additional_bytes = additional.checked_mul(size_of::<T>()).unwrap();
         available_bytes >= additional_bytes
     }
 
     #[inline]
     fn alloc_raw_slice(&self, len: usize) -> *mut T {
-        assert!(mem::size_of::<T>() != 0);
+        assert!(size_of::<T>() != 0);
         assert!(len != 0);
 
         // Ensure the current chunk can fit `len` objects.
@@ -213,7 +213,7 @@ impl<T> TypedArena<T> {
         // So we collect all the elements beforehand, which takes care of reentrancy and panic
         // safety. This function is much less hot than `DroplessArena::alloc_from_iter`, so it
         // doesn't need to be hyper-optimized.
-        assert!(mem::size_of::<T>() != 0);
+        assert!(size_of::<T>() != 0);
 
         let mut vec: SmallVec<[_; 8]> = iter.into_iter().collect();
         if vec.is_empty() {
@@ -236,7 +236,7 @@ impl<T> TypedArena<T> {
         unsafe {
             // We need the element size to convert chunk sizes (ranging from
             // PAGE to HUGE_PAGE bytes) to element counts.
-            let elem_size = cmp::max(1, mem::size_of::<T>());
+            let elem_size = cmp::max(1, size_of::<T>());
             let mut chunks = self.chunks.borrow_mut();
             let mut new_cap;
             if let Some(last_chunk) = chunks.last_mut() {
@@ -246,7 +246,7 @@ impl<T> TypedArena<T> {
                     // FIXME: this should *likely* use `offset_from`, but more
                     // investigation is needed (including running tests in miri).
                     let used_bytes = self.ptr.get().addr() - last_chunk.start().addr();
-                    last_chunk.entries = used_bytes / mem::size_of::<T>();
+                    last_chunk.entries = used_bytes / size_of::<T>();
                 }
 
                 // If the previous chunk's len is less than HUGE_PAGE
@@ -276,15 +276,15 @@ impl<T> TypedArena<T> {
         let end = self.ptr.get().addr();
         // We then calculate the number of elements to be dropped in the last chunk,
         // which is the filled area's length.
-        let diff = if mem::size_of::<T>() == 0 {
+        let diff = if size_of::<T>() == 0 {
             // `T` is ZST. It can't have a drop flag, so the value here doesn't matter. We get
             // the number of zero-sized values in the last and only chunk, just out of caution.
             // Recall that `end` was incremented for each allocated value.
             end - start
         } else {
             // FIXME: this should *likely* use `offset_from`, but more
             // investigation is needed (including running tests in miri).
-            (end - start) / mem::size_of::<T>()
+            (end - start) / size_of::<T>()
         };
         // Pass that to the `destroy` method.
         unsafe {
@@ -329,7 +329,7 @@ fn align_up(val: usize, align: usize) -> usize {
 
 // Pointer alignment is common in compiler types, so keep `DroplessArena` aligned to them
 // to optimize away alignment code.
-const DROPLESS_ALIGNMENT: usize = mem::align_of::<usize>();
+const DROPLESS_ALIGNMENT: usize = align_of::<usize>();
 
 /// An arena that can hold objects of multiple different types that impl `Copy`
 /// and/or satisfy `!mem::needs_drop`.
@@ -447,7 +447,7 @@ impl DroplessArena {
     #[inline]
     pub fn alloc<T>(&self, object: T) -> &mut T {
         assert!(!mem::needs_drop::<T>());
-        assert!(mem::size_of::<T>() != 0);
+        assert!(size_of::<T>() != 0);
 
         let mem = self.alloc_raw(Layout::new::<T>()) as *mut T;
 
@@ -471,7 +471,7 @@ impl DroplessArena {
         T: Copy,
     {
         assert!(!mem::needs_drop::<T>());
-        assert!(mem::size_of::<T>() != 0);
+        assert!(size_of::<T>() != 0);
         assert!(!slice.is_empty());
 
         let mem = self.alloc_raw(Layout::for_value::<[T]>(slice)) as *mut T;
@@ -546,7 +546,7 @@ impl DroplessArena {
         // Warning: this function is reentrant: `iter` could hold a reference to `&self` and
         // allocate additional elements while we're iterating.
         let iter = iter.into_iter();
-        assert!(mem::size_of::<T>() != 0);
+        assert!(size_of::<T>() != 0);
         assert!(!mem::needs_drop::<T>());
 
         let size_hint = iter.size_hint();

compiler/rustc_codegen_gcc/src/builder.rs

@@ -2439,9 +2439,5 @@ fn get_maybe_pointer_size(value: RValue<'_>) -> u32 {
 #[cfg(not(feature = "master"))]
 fn get_maybe_pointer_size(value: RValue<'_>) -> u32 {
     let type_ = value.get_type();
-    if type_.get_pointee().is_some() {
-        std::mem::size_of::<*const ()>() as _
-    } else {
-        type_.get_size()
-    }
+    if type_.get_pointee().is_some() { size_of::<*const ()>() as _ } else { type_.get_size() }
 }

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1177,7 +1177,7 @@ mod win {
             let mut cp: u32 = 0;
             // We're using the `LOCALE_RETURN_NUMBER` flag to return a u32.
             // But the API requires us to pass the data as though it's a [u16] string.
-            let len = std::mem::size_of::<u32>() / std::mem::size_of::<u16>();
+            let len = size_of::<u32>() / size_of::<u16>();
             let data = std::slice::from_raw_parts_mut(&mut cp as *mut u32 as *mut u16, len);
             let len_written = GetLocaleInfoEx(
                 LOCALE_NAME_SYSTEM_DEFAULT,

compiler/rustc_data_structures/src/aligned.rs

@@ -2,10 +2,8 @@ use std::ptr::Alignment;
 
 /// Returns the ABI-required minimum alignment of a type in bytes.
 ///
-/// This is equivalent to [`mem::align_of`], but also works for some unsized
+/// This is equivalent to [`align_of`], but also works for some unsized
 /// types (e.g. slices or rustc's `List`s).
-///
-/// [`mem::align_of`]: std::mem::align_of
 pub const fn align_of<T: ?Sized + Aligned>() -> Alignment {
     T::ALIGN
 }
@@ -15,10 +13,10 @@ pub const fn align_of<T: ?Sized + Aligned>() -> Alignment {
 /// # Safety
 ///
 /// `Self::ALIGN` must be equal to the alignment of `Self`. For sized types it
-/// is [`mem::align_of<Self>()`], for unsized types it depends on the type, for
+/// is [`align_of::<Self>()`], for unsized types it depends on the type, for
 /// example `[T]` has alignment of `T`.
 ///
-/// [`mem::align_of<Self>()`]: std::mem::align_of
+/// [`align_of::<Self>()`]: align_of
 pub unsafe trait Aligned {
     /// Alignment of `Self`.
     const ALIGN: Alignment;

compiler/rustc_data_structures/src/profiling.rs

@@ -863,15 +863,13 @@ fn get_thread_id() -> u32 {
 cfg_match! {
     windows => {
         pub fn get_resident_set_size() -> Option<usize> {
-            use std::mem;
-
             use windows::{
                 Win32::System::ProcessStatus::{K32GetProcessMemoryInfo, PROCESS_MEMORY_COUNTERS},
                 Win32::System::Threading::GetCurrentProcess,
             };
 
             let mut pmc = PROCESS_MEMORY_COUNTERS::default();
-            let pmc_size = mem::size_of_val(&pmc);
+            let pmc_size = size_of_val(&pmc);
             unsafe {
                 K32GetProcessMemoryInfo(
                     GetCurrentProcess(),
@@ -889,7 +887,7 @@ cfg_match! {
         pub fn get_resident_set_size() -> Option<usize> {
             use libc::{c_int, c_void, getpid, proc_pidinfo, proc_taskinfo, PROC_PIDTASKINFO};
             use std::mem;
-            const PROC_TASKINFO_SIZE: c_int = mem::size_of::<proc_taskinfo>() as c_int;
+            const PROC_TASKINFO_SIZE: c_int = size_of::<proc_taskinfo>() as c_int;
 
             unsafe {
                 let mut info: proc_taskinfo = mem::zeroed();

compiler/rustc_data_structures/src/sharded.rs

@@ -1,7 +1,7 @@
 use std::borrow::Borrow;
 use std::collections::hash_map::RawEntryMut;
 use std::hash::{Hash, Hasher};
-use std::{iter, mem};
+use std::iter;
 
 use either::Either;
 
@@ -221,7 +221,7 @@ pub fn make_hash<K: Hash + ?Sized>(val: &K) -> u64 {
 /// consistently for each `Sharded` instance.
 #[inline]
 fn get_shard_hash(hash: u64) -> usize {
-    let hash_len = mem::size_of::<usize>();
+    let hash_len = size_of::<usize>();
     // Ignore the top 7 bits as hashbrown uses these and get the next SHARD_BITS highest bits.
     // hashbrown also uses the lowest bits, so we can't use those
     (hash >> (hash_len * 8 - 7 - SHARD_BITS)) as usize

compiler/rustc_errors/src/diagnostic.rs

@@ -490,7 +490,7 @@ pub struct Diag<'a, G: EmissionGuarantee = ErrorGuaranteed> {
 // would be bad.
 impl<G> !Clone for Diag<'_, G> {}
 
-rustc_data_structures::static_assert_size!(Diag<'_, ()>, 3 * std::mem::size_of::<usize>());
+rustc_data_structures::static_assert_size!(Diag<'_, ()>, 3 * size_of::<usize>());
 
 impl<G: EmissionGuarantee> Deref for Diag<'_, G> {
     type Target = DiagInner;

compiler/rustc_hir/src/def.rs

@@ -435,7 +435,7 @@ pub enum Res<Id = hir::HirId> {
         /// mention any generic parameters to allow the following with `min_const_generics`:
         /// ```
         /// # struct Foo;
-        /// impl Foo { fn test() -> [u8; std::mem::size_of::<Self>()] { todo!() } }
+        /// impl Foo { fn test() -> [u8; size_of::<Self>()] { todo!() } }
         ///
         /// struct Bar([u8; baz::<Self>()]);
         /// const fn baz<T>() -> usize { 10 }
@@ -445,7 +445,7 @@ pub enum Res<Id = hir::HirId> {
         /// compat lint:
         /// ```
         /// fn foo<T>() {
-        ///     let _bar = [1_u8; std::mem::size_of::<*mut T>()];
+        ///     let _bar = [1_u8; size_of::<*mut T>()];
         /// }
         /// ```
         // FIXME(generic_const_exprs): Remove this bodge once that feature is stable.

compiler/rustc_incremental/src/persist/file_format.rs

@@ -123,7 +123,7 @@ pub(crate) fn read_file(
 
     // Check HEADER_FORMAT_VERSION
     {
-        debug_assert!(::std::mem::size_of_val(&HEADER_FORMAT_VERSION) == 2);
+        debug_assert!(size_of_val(&HEADER_FORMAT_VERSION) == 2);
         let mut header_format_version = [0u8; 2];
         file.read_exact(&mut header_format_version)?;
         let header_format_version =

compiler/rustc_index/src/bit_set.rs

@@ -1,7 +1,9 @@
 use std::marker::PhantomData;
+#[cfg(not(feature = "nightly"))]
+use std::mem;
 use std::ops::{BitAnd, BitAndAssign, BitOrAssign, Bound, Not, Range, RangeBounds, Shl};
 use std::rc::Rc;
-use std::{fmt, iter, mem, slice};
+use std::{fmt, iter, slice};
 
 use Chunk::*;
 #[cfg(feature = "nightly")]
@@ -14,7 +16,7 @@ use crate::{Idx, IndexVec};
 mod tests;
 
 type Word = u64;
-const WORD_BYTES: usize = mem::size_of::<Word>();
+const WORD_BYTES: usize = size_of::<Word>();
 const WORD_BITS: usize = WORD_BYTES * 8;
 
 // The choice of chunk size has some trade-offs.

compiler/rustc_index/src/vec/tests.rs

@@ -9,8 +9,6 @@ crate::newtype_index! {
 
 #[test]
 fn index_size_is_optimized() {
-    use std::mem::size_of;
-
     assert_eq!(size_of::<MyIdx>(), 4);
     // Uses 0xFFFF_FFFB
     assert_eq!(size_of::<Option<MyIdx>>(), 4);

compiler/rustc_lint_defs/src/builtin.rs

@@ -2673,7 +2673,7 @@ declare_lint! {
     ///
     /// ```rust
     /// const fn foo<T>() -> usize {
-    ///     if std::mem::size_of::<*mut T>() < 8 { // size of *mut T does not depend on T
+    ///     if size_of::<*mut T>() < 8 { // size of *mut T does not depend on T
     ///         4
     ///     } else {
     ///         8

compiler/rustc_middle/src/mir/interpret/allocation/init_mask.rs

@@ -223,8 +223,8 @@ impl<D: TyDecoder> Decodable<D> for InitMaskMaterialized {
 // large.
 impl hash::Hash for InitMaskMaterialized {
     fn hash<H: hash::Hasher>(&self, state: &mut H) {
-        const MAX_BLOCKS_TO_HASH: usize = super::MAX_BYTES_TO_HASH / std::mem::size_of::<Block>();
-        const MAX_BLOCKS_LEN: usize = super::MAX_HASHED_BUFFER_LEN / std::mem::size_of::<Block>();
+        const MAX_BLOCKS_TO_HASH: usize = super::MAX_BYTES_TO_HASH / size_of::<Block>();
+        const MAX_BLOCKS_LEN: usize = super::MAX_HASHED_BUFFER_LEN / size_of::<Block>();
 
         // Partially hash the `blocks` buffer when it is large. To limit collisions with common
         // prefixes and suffixes, we hash the length and some slices of the buffer.

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -573,7 +573,7 @@ pub fn write_target_uint(
 #[inline]
 pub fn read_target_uint(endianness: Endian, mut source: &[u8]) -> Result<u128, io::Error> {
     // This u128 holds an "any-size uint" (since smaller uints can fits in it)
-    let mut buf = [0u8; std::mem::size_of::<u128>()];
+    let mut buf = [0u8; size_of::<u128>()];
     // So we do not read exactly 16 bytes into the u128, just the "payload".
     let uint = match endianness {
         Endian::Little => {

compiler/rustc_middle/src/mir/mod.rs

@@ -332,13 +332,13 @@ pub struct Body<'tcx> {
     ///
     /// ```rust
     /// fn test<T>() {
-    ///     let _ = [0; std::mem::size_of::<*mut T>()];
+    ///     let _ = [0; size_of::<*mut T>()];
     /// }
     /// ```
     ///
     /// **WARNING**: Do not change this flags after the MIR was originally created, even if an optimization
     /// removed the last mention of all generic params. We do not want to rely on optimizations and
-    /// potentially allow things like `[u8; std::mem::size_of::<T>() * 0]` due to this.
+    /// potentially allow things like `[u8; size_of::<T>() * 0]` due to this.
     pub is_polymorphic: bool,
 
     /// The phase at which this MIR should be "injected" into the compilation process.

compiler/rustc_middle/src/query/erase.rs

@@ -27,7 +27,7 @@ pub type Erase<T: EraseType> = Erased<impl Copy>;
 pub fn erase<T: EraseType>(src: T) -> Erase<T> {
     // Ensure the sizes match
     const {
-        if std::mem::size_of::<T>() != std::mem::size_of::<T::Result>() {
+        if size_of::<T>() != size_of::<T::Result>() {
             panic!("size of T must match erased type T::Result")
         }
     };

compiler/rustc_middle/src/query/plumbing.rs

@@ -370,7 +370,7 @@ macro_rules! define_callbacks {
                 // Increase this limit if necessary, but do try to keep the size low if possible
                 #[cfg(target_pointer_width = "64")]
                 const _: () = {
-                    if mem::size_of::<Key<'static>>() > 88 {
+                    if size_of::<Key<'static>>() > 88 {
                         panic!("{}", concat!(
                             "the query `",
                             stringify!($name),
@@ -386,7 +386,7 @@ macro_rules! define_callbacks {
                 #[cfg(target_pointer_width = "64")]
                 #[cfg(not(feature = "rustc_randomized_layouts"))]
                 const _: () = {
-                    if mem::size_of::<Value<'static>>() > 64 {
+                    if size_of::<Value<'static>>() > 64 {
                         panic!("{}", concat!(
                             "the query `",
                             stringify!($name),

compiler/rustc_middle/src/ty/consts/int.rs

@@ -408,7 +408,7 @@ macro_rules! from_x_for_scalar_int {
                 fn from(u: $ty) -> Self {
                     Self {
                         data: u128::from(u),
-                        size: NonZero::new(std::mem::size_of::<$ty>() as u8).unwrap(),
+                        size: NonZero::new(size_of::<$ty>() as u8).unwrap(),
                     }
                 }
             }
@@ -424,7 +424,7 @@ macro_rules! from_scalar_int_for_x {
                 fn from(int: ScalarInt) -> Self {
                     // The `unwrap` cannot fail because to_bits (if it succeeds)
                     // is guaranteed to return a value that fits into the size.
-                    int.to_bits(Size::from_bytes(std::mem::size_of::<$ty>()))
+                    int.to_bits(Size::from_bytes(size_of::<$ty>()))
                        .try_into().unwrap()
                 }
             }

compiler/rustc_middle/src/ty/generic_args.rs

@@ -2,7 +2,6 @@
 
 use core::intrinsics;
 use std::marker::PhantomData;
-use std::mem;
 use std::num::NonZero;
 use std::ptr::NonNull;
 
@@ -176,17 +175,17 @@ impl<'tcx> GenericArgKind<'tcx> {
         let (tag, ptr) = match self {
             GenericArgKind::Lifetime(lt) => {
                 // Ensure we can use the tag bits.
-                assert_eq!(mem::align_of_val(&*lt.0.0) & TAG_MASK, 0);
+                assert_eq!(align_of_val(&*lt.0.0) & TAG_MASK, 0);
                 (REGION_TAG, NonNull::from(lt.0.0).cast())
             }
             GenericArgKind::Type(ty) => {
                 // Ensure we can use the tag bits.
-                assert_eq!(mem::align_of_val(&*ty.0.0) & TAG_MASK, 0);
+                assert_eq!(align_of_val(&*ty.0.0) & TAG_MASK, 0);
                 (TYPE_TAG, NonNull::from(ty.0.0).cast())
             }
             GenericArgKind::Const(ct) => {
                 // Ensure we can use the tag bits.
-                assert_eq!(mem::align_of_val(&*ct.0.0) & TAG_MASK, 0);
+                assert_eq!(align_of_val(&*ct.0.0) & TAG_MASK, 0);
                 (CONST_TAG, NonNull::from(ct.0.0).cast())
             }
         };