From a5a60d75a87881f79deea115d7cd002ce3373fd5 Mon Sep 17 00:00:00 2001 From: Josh Triplett Date: Thu, 28 Mar 2024 14:30:32 +0000 Subject: [PATCH] Add `size_of`, `size_of_val`, `align_of`, and `align_of_val` to the prelude Many, many projects use `size_of` to get the size of a type. However, it's also often equally easy to hardcode a size (e.g. `8` instead of `size_of::()`). Minimizing friction in the use of `size_of` helps ensure that people use it and make code more self-documenting. The name `size_of` is unambiguous: the name alone, without any prefix or path, is self-explanatory and unmistakeable for any other functionality. Adding it to the prelude cannot produce any name conflicts, as any local definition will silently shadow the one from the prelude. Thus, we don't need to wait for a new edition prelude to add it. Add `size_of_val`, `align_of`, and `align_of_val` as well, with similar justification: widely useful, self-explanatory, unmistakeable for anything else, won't produce conflicts. --- compiler/rustc_middle/src/query/erase.rs | 2 +- library/alloc/src/rc.rs | 2 -- library/alloc/src/sync.rs | 2 -- library/core/src/cell.rs | 2 +- library/core/src/intrinsics.rs | 1 - library/core/src/prelude/common.rs | 3 +++ library/core/src/ptr/mod.rs | 2 +- library/core/src/slice/raw.rs | 1 - library/core/src/sync/atomic.rs | 3 --- .../crates/core_simd/src/simd/ptr/const_ptr.rs | 2 +- .../crates/core_simd/src/simd/ptr/mut_ptr.rs | 2 +- library/proc_macro/src/bridge/fxhash.rs | 1 - library/std/src/io/error/repr_bitpacked.rs | 1 - library/std/src/os/unix/net/ancillary.rs | 2 +- library/std/src/prelude/common.rs | 3 +++ library/std/src/prelude/mod.rs | 4 ++++ tests/ui/resolve/filter-intrinsics.rs | 4 ++-- tests/ui/resolve/filter-intrinsics.stderr | 8 ++++---- 18 files changed, 22 insertions(+), 23 deletions(-) diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs index 320d49ea646..a4ab6bc7d9d 100644 --- a/compiler/rustc_middle/src/query/erase.rs +++ b/compiler/rustc_middle/src/query/erase.rs @@ -4,7 +4,7 @@ use crate::traits; use crate::ty::adjustment::CoerceUnsizedInfo; use crate::ty::{self, Ty}; use std::intrinsics::transmute_unchecked; -use std::mem::{size_of, MaybeUninit}; +use std::mem::MaybeUninit; #[derive(Copy, Clone)] pub struct Erased { diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs index 45b20535675..52b91c5ac88 100644 --- a/library/alloc/src/rc.rs +++ b/library/alloc/src/rc.rs @@ -257,8 +257,6 @@ use core::intrinsics::abort; #[cfg(not(no_global_oom_handling))] use core::iter; use core::marker::{PhantomData, Unsize}; -#[cfg(not(no_global_oom_handling))] -use core::mem::size_of_val; use core::mem::{self, align_of_val_raw, forget, ManuallyDrop}; use core::ops::{CoerceUnsized, Deref, DerefMut, DerefPure, DispatchFromDyn, Receiver}; use core::panic::{RefUnwindSafe, UnwindSafe}; diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs index a35c99849b3..d7c3a261fe4 100644 --- a/library/alloc/src/sync.rs +++ b/library/alloc/src/sync.rs @@ -18,8 +18,6 @@ use core::intrinsics::abort; #[cfg(not(no_global_oom_handling))] use core::iter; use core::marker::{PhantomData, Unsize}; -#[cfg(not(no_global_oom_handling))] -use core::mem::size_of_val; use core::mem::{self, align_of_val_raw}; use core::ops::{CoerceUnsized, Deref, DerefPure, DispatchFromDyn, Receiver}; use core::panic::{RefUnwindSafe, UnwindSafe}; diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs index 4b491ffdafa..dd6466d6285 100644 --- a/library/core/src/cell.rs +++ b/library/core/src/cell.rs @@ -238,7 +238,7 @@ use crate::cmp::Ordering; use crate::fmt::{self, Debug, Display}; use crate::marker::{PhantomData, Unsize}; -use crate::mem::{self, size_of}; +use crate::mem; use crate::ops::{CoerceUnsized, Deref, DerefMut, DerefPure, DispatchFromDyn}; use crate::ptr::{self, NonNull}; diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs index d1450bf12ce..56c998d99f2 100644 --- a/library/core/src/intrinsics.rs +++ b/library/core/src/intrinsics.rs @@ -65,7 +65,6 @@ use crate::marker::DiscriminantKind; use crate::marker::Tuple; -use crate::mem::align_of; use crate::ptr; use crate::ub_checks; diff --git a/library/core/src/prelude/common.rs b/library/core/src/prelude/common.rs index afc6817aa1d..2a0331ef7b2 100644 --- a/library/core/src/prelude/common.rs +++ b/library/core/src/prelude/common.rs @@ -14,6 +14,9 @@ pub use crate::ops::{Drop, Fn, FnMut, FnOnce}; #[stable(feature = "core_prelude", since = "1.4.0")] #[doc(no_inline)] pub use crate::mem::drop; +#[stable(feature = "size_of_prelude", since = "CURRENT_RUSTC_VERSION")] +#[doc(no_inline)] +pub use crate::mem::{align_of, align_of_val, size_of, size_of_val}; // Re-exported types and traits #[stable(feature = "core_prelude", since = "1.4.0")] diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs index 8d7192c1b0f..3258e338e83 100644 --- a/library/core/src/ptr/mod.rs +++ b/library/core/src/ptr/mod.rs @@ -392,7 +392,7 @@ use crate::intrinsics; use crate::marker::FnPtr; use crate::ub_checks; -use crate::mem::{self, align_of, size_of, MaybeUninit}; +use crate::mem::{self, MaybeUninit}; mod alignment; #[unstable(feature = "ptr_alignment_type", issue = "102070")] diff --git a/library/core/src/slice/raw.rs b/library/core/src/slice/raw.rs index 29a12f106c5..3f4305866e6 100644 --- a/library/core/src/slice/raw.rs +++ b/library/core/src/slice/raw.rs @@ -1,7 +1,6 @@ //! Free functions to create `&[T]` and `&mut [T]`. use crate::array; -use crate::mem::{align_of, size_of}; use crate::ops::Range; use crate::ptr; use crate::ub_checks; diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs index 232ec589093..482bd19705c 100644 --- a/library/core/src/sync/atomic.rs +++ b/library/core/src/sync/atomic.rs @@ -1296,7 +1296,6 @@ impl AtomicPtr { #[cfg(target_has_atomic_equal_alignment = "ptr")] #[unstable(feature = "atomic_from_mut", issue = "76314")] pub fn from_mut(v: &mut *mut T) -> &mut Self { - use crate::mem::align_of; let [] = [(); align_of::>() - align_of::<*mut ()>()]; // SAFETY: // - the mutable reference guarantees unique ownership. @@ -2286,7 +2285,6 @@ macro_rules! atomic_int { #[$cfg_align] #[unstable(feature = "atomic_from_mut", issue = "76314")] pub fn from_mut(v: &mut $int_type) -> &mut Self { - use crate::mem::align_of; let [] = [(); align_of::() - align_of::<$int_type>()]; // SAFETY: // - the mutable reference guarantees unique ownership. @@ -2354,7 +2352,6 @@ macro_rules! atomic_int { #[$cfg_align] #[unstable(feature = "atomic_from_mut", issue = "76314")] pub fn from_mut_slice(v: &mut [$int_type]) -> &mut [Self] { - use crate::mem::align_of; let [] = [(); align_of::() - align_of::<$int_type>()]; // SAFETY: // - the mutable reference guarantees unique ownership. diff --git a/library/portable-simd/crates/core_simd/src/simd/ptr/const_ptr.rs b/library/portable-simd/crates/core_simd/src/simd/ptr/const_ptr.rs index 0f1719206c9..cbffbc564cf 100644 --- a/library/portable-simd/crates/core_simd/src/simd/ptr/const_ptr.rs +++ b/library/portable-simd/crates/core_simd/src/simd/ptr/const_ptr.rs @@ -96,7 +96,7 @@ where fn cast(self) -> Self::CastPtr { // SimdElement currently requires zero-sized metadata, so this should never fail. // If this ever changes, `simd_cast_ptr` should produce a post-mono error. - use core::{mem::size_of, ptr::Pointee}; + use core::ptr::Pointee; assert_eq!(size_of::<::Metadata>(), 0); assert_eq!(size_of::<::Metadata>(), 0); diff --git a/library/portable-simd/crates/core_simd/src/simd/ptr/mut_ptr.rs b/library/portable-simd/crates/core_simd/src/simd/ptr/mut_ptr.rs index 7ba996d149c..6bc6ca3ac42 100644 --- a/library/portable-simd/crates/core_simd/src/simd/ptr/mut_ptr.rs +++ b/library/portable-simd/crates/core_simd/src/simd/ptr/mut_ptr.rs @@ -93,7 +93,7 @@ where fn cast(self) -> Self::CastPtr { // SimdElement currently requires zero-sized metadata, so this should never fail. // If this ever changes, `simd_cast_ptr` should produce a post-mono error. - use core::{mem::size_of, ptr::Pointee}; + use core::ptr::Pointee; assert_eq!(size_of::<::Metadata>(), 0); assert_eq!(size_of::<::Metadata>(), 0); diff --git a/library/proc_macro/src/bridge/fxhash.rs b/library/proc_macro/src/bridge/fxhash.rs index f4e90544197..0923493d06c 100644 --- a/library/proc_macro/src/bridge/fxhash.rs +++ b/library/proc_macro/src/bridge/fxhash.rs @@ -7,7 +7,6 @@ use std::collections::HashMap; use std::hash::BuildHasherDefault; use std::hash::Hasher; -use std::mem::size_of; use std::ops::BitXor; /// Type alias for a hashmap using the `fx` hash algorithm. diff --git a/library/std/src/io/error/repr_bitpacked.rs b/library/std/src/io/error/repr_bitpacked.rs index 6f8d5e37775..c9d3934ad70 100644 --- a/library/std/src/io/error/repr_bitpacked.rs +++ b/library/std/src/io/error/repr_bitpacked.rs @@ -104,7 +104,6 @@ use super::{Custom, ErrorData, ErrorKind, RawOsError, SimpleMessage}; use core::marker::PhantomData; -use core::mem::{align_of, size_of}; use core::ptr::{self, NonNull}; // The 2 least-significant bits are used as tag. diff --git a/library/std/src/os/unix/net/ancillary.rs b/library/std/src/os/unix/net/ancillary.rs index 0597fdcbd72..fe8e2be9372 100644 --- a/library/std/src/os/unix/net/ancillary.rs +++ b/library/std/src/os/unix/net/ancillary.rs @@ -3,7 +3,7 @@ use super::{sockaddr_un, SocketAddr}; use crate::io::{self, IoSlice, IoSliceMut}; use crate::marker::PhantomData; -use crate::mem::{size_of, zeroed}; +use crate::mem::zeroed; use crate::os::unix::io::RawFd; use crate::path::Path; use crate::ptr::{eq, read_unaligned}; diff --git a/library/std/src/prelude/common.rs b/library/std/src/prelude/common.rs index 01936734d75..ceee3e33c3e 100644 --- a/library/std/src/prelude/common.rs +++ b/library/std/src/prelude/common.rs @@ -14,6 +14,9 @@ pub use crate::ops::{Drop, Fn, FnMut, FnOnce}; #[stable(feature = "rust1", since = "1.0.0")] #[doc(no_inline)] pub use crate::mem::drop; +#[stable(feature = "size_of_prelude", since = "CURRENT_RUSTC_VERSION")] +#[doc(no_inline)] +pub use crate::mem::{align_of, align_of_val, size_of, size_of_val}; // Re-exported types and traits #[stable(feature = "rust1", since = "1.0.0")] diff --git a/library/std/src/prelude/mod.rs b/library/std/src/prelude/mod.rs index 0bdbab716ad..2d4639342bf 100644 --- a/library/std/src/prelude/mod.rs +++ b/library/std/src/prelude/mod.rs @@ -36,6 +36,10 @@ //! operations for both destructors and overloading `()`. //! * [std::mem]::[drop], a convenience function for explicitly //! dropping a value. +//! * [std::mem]::{[size_of], [size_of_val]}, to get the size of +//! a type or value. +//! * [std::mem]::{[align_of], [align_of_val]}, to get the +//! alignment of a type or value. //! * [std::boxed]::[Box], a way to allocate values on the heap. //! * [std::borrow]::[ToOwned], the conversion trait that defines //! [`to_owned`], the generic method for creating an owned type from a diff --git a/tests/ui/resolve/filter-intrinsics.rs b/tests/ui/resolve/filter-intrinsics.rs index c0956ef85af..8d6d22817dc 100644 --- a/tests/ui/resolve/filter-intrinsics.rs +++ b/tests/ui/resolve/filter-intrinsics.rs @@ -1,6 +1,6 @@ fn main() { - // Should suggest only `std::mem::size_of` - let _ = size_of::(); + // Should suggest only `std::mem::transmute` + let _ = transmute::(); //~^ ERROR cannot find // Should suggest `std::intrinsics::fabsf64`, diff --git a/tests/ui/resolve/filter-intrinsics.stderr b/tests/ui/resolve/filter-intrinsics.stderr index cc1092dd0cf..9c9e92f6d4f 100644 --- a/tests/ui/resolve/filter-intrinsics.stderr +++ b/tests/ui/resolve/filter-intrinsics.stderr @@ -1,12 +1,12 @@ -error[E0425]: cannot find function `size_of` in this scope +error[E0425]: cannot find function `transmute` in this scope --> $DIR/filter-intrinsics.rs:3:13 | -LL | let _ = size_of::(); - | ^^^^^^^ not found in this scope +LL | let _ = transmute::(); + | ^^^^^^^^^ not found in this scope | help: consider importing this function | -LL + use std::mem::size_of; +LL + use std::mem::transmute; | error[E0425]: cannot find function `fabsf64` in this scope