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Rollup merge of #135003 - RalfJung:deprecate-allowed-through-unstable, r=davidtwco

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deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead

The `rustc_allowed_through_unstable_modules` attribute lets users call `std::mem::transmute` as `std::intrinsics::transmute`. The former is a reexport of the latter, and for a long time we didn't properly check stability for reexports, so making this a hard error now would be a breaking change for little gain. But at the same time, `std::intrinsics::transmute` is not the intended path for this function, so I think it is a good idea to show a deprecation warning when that path is used. This PR implements that, for all the functions in `std::intrinsics` that carry the attribute.

I assume this will need ``@rust-lang/libs-api`` FCP.
This commit is contained in:
Guillaume Gomez 2025-01-15 16:30:11 +01:00 • committed by GitHub
commit e31493b9b8
5 changed files with 32 additions and 32 deletions
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2
clippy_lints/src/std_instead_of_core.rs
View file

@ -180,7 +180,7 @@ fn is_stable(cx: &LateContext<'_>, mut def_id: DefId, msrv: &Msrv) -> bool {
if let Some(stability) = cx.tcx.lookup_stability(def_id)
&& let StabilityLevel::Stable {
since,
allowed_through_unstable_modules: false,
allowed_through_unstable_modules: None,
} = stability.level
{
let stable = match since {

2
tests/ui/std_instead_of_core.fixed
View file

@ -1,7 +1,7 @@
//@aux-build:proc_macro_derive.rs
#![warn(clippy::std_instead_of_core)]
#![allow(unused_imports)]
#![allow(unused_imports, deprecated)]
extern crate alloc;

2
tests/ui/std_instead_of_core.rs
View file

@ -1,7 +1,7 @@
//@aux-build:proc_macro_derive.rs
#![warn(clippy::std_instead_of_core)]
#![allow(unused_imports)]
#![allow(unused_imports, deprecated)]
extern crate alloc;

22
tests/ui/transmute.rs
View file

@ -24,31 +24,31 @@ fn my_vec() -> MyVec<i32> {
#[warn(clippy::useless_transmute)]
unsafe fn _generic<'a, T, U: 'a>(t: &'a T) {
// FIXME: should lint
// let _: &'a T = core::intrinsics::transmute(t);
// let _: &'a T = core::mem::transmute(t);
let _: &'a U = core::intrinsics::transmute(t);
let _: &'a U = core::mem::transmute(t);
let _: *const T = core::intrinsics::transmute(t);
let _: *const T = core::mem::transmute(t);
//~^ ERROR: transmute from a reference to a pointer
//~| NOTE: `-D clippy::useless-transmute` implied by `-D warnings`
let _: *mut T = core::intrinsics::transmute(t);
let _: *mut T = core::mem::transmute(t);
//~^ ERROR: transmute from a reference to a pointer
let _: *const U = core::intrinsics::transmute(t);
let _: *const U = core::mem::transmute(t);
//~^ ERROR: transmute from a reference to a pointer
}
#[warn(clippy::useless_transmute)]
fn useless() {
unsafe {
let _: Vec<i32> = core::intrinsics::transmute(my_vec());
let _: Vec<i32> = core::mem::transmute(my_vec());
//~^ ERROR: transmute from a type (`std::vec::Vec<i32>`) to itself
let _: Vec<i32> = core::mem::transmute(my_vec());
//~^ ERROR: transmute from a type (`std::vec::Vec<i32>`) to itself
let _: Vec<i32> = std::intrinsics::transmute(my_vec());
let _: Vec<i32> = std::mem::transmute(my_vec());
//~^ ERROR: transmute from a type (`std::vec::Vec<i32>`) to itself
let _: Vec<i32> = std::mem::transmute(my_vec());
@ -94,17 +94,17 @@ fn crosspointer() {
let int_mut_ptr: *mut Usize = &mut int as *mut Usize;
unsafe {
let _: Usize = core::intrinsics::transmute(int_const_ptr);
let _: Usize = core::mem::transmute(int_const_ptr);
//~^ ERROR: transmute from a type (`*const Usize`) to the type that it points to (
//~| NOTE: `-D clippy::crosspointer-transmute` implied by `-D warnings`
let _: Usize = core::intrinsics::transmute(int_mut_ptr);
let _: Usize = core::mem::transmute(int_mut_ptr);
//~^ ERROR: transmute from a type (`*mut Usize`) to the type that it points to (`U
let _: *const Usize = core::intrinsics::transmute(my_int());
let _: *const Usize = core::mem::transmute(my_int());
//~^ ERROR: transmute from a type (`Usize`) to a pointer to that type (`*const Usi
let _: *mut Usize = core::intrinsics::transmute(my_int());
let _: *mut Usize = core::mem::transmute(my_int());
//~^ ERROR: transmute from a type (`Usize`) to a pointer to that type (`*mut Usize
}
}

36
tests/ui/transmute.stderr
View file

@ -1,8 +1,8 @@
error: transmute from a reference to a pointer
--> tests/ui/transmute.rs:31:23
|
LL | let _: *const T = core::intrinsics::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T`
LL | let _: *const T = core::mem::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T`
|
= note: `-D clippy::useless-transmute` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::useless_transmute)]`
@ -10,20 +10,20 @@ LL | let _: *const T = core::intrinsics::transmute(t);
error: transmute from a reference to a pointer
--> tests/ui/transmute.rs:35:21
|
LL | let _: *mut T = core::intrinsics::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *mut T`
LL | let _: *mut T = core::mem::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *mut T`
error: transmute from a reference to a pointer
--> tests/ui/transmute.rs:38:23
|
LL | let _: *const U = core::intrinsics::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *const U`
LL | let _: *const U = core::mem::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *const U`
error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> tests/ui/transmute.rs:45:27
|
LL | let _: Vec<i32> = core::intrinsics::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _: Vec<i32> = core::mem::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> tests/ui/transmute.rs:48:27
@ -34,8 +34,8 @@ LL | let _: Vec<i32> = core::mem::transmute(my_vec());
error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> tests/ui/transmute.rs:51:27
|
LL | let _: Vec<i32> = std::intrinsics::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _: Vec<i32> = std::mem::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> tests/ui/transmute.rs:54:27
@ -64,8 +64,8 @@ LL | let _: *const usize = std::mem::transmute(1 + 1usize);
error: transmute from a type (`*const Usize`) to the type that it points to (`Usize`)
--> tests/ui/transmute.rs:97:24
|
LL | let _: Usize = core::intrinsics::transmute(int_const_ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _: Usize = core::mem::transmute(int_const_ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::crosspointer-transmute` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::crosspointer_transmute)]`
@ -73,20 +73,20 @@ LL | let _: Usize = core::intrinsics::transmute(int_const_ptr);
error: transmute from a type (`*mut Usize`) to the type that it points to (`Usize`)
--> tests/ui/transmute.rs:101:24
|
LL | let _: Usize = core::intrinsics::transmute(int_mut_ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _: Usize = core::mem::transmute(int_mut_ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: transmute from a type (`Usize`) to a pointer to that type (`*const Usize`)
--> tests/ui/transmute.rs:104:31
|
LL | let _: *const Usize = core::intrinsics::transmute(my_int());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _: *const Usize = core::mem::transmute(my_int());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: transmute from a type (`Usize`) to a pointer to that type (`*mut Usize`)
--> tests/ui/transmute.rs:107:29
|
LL | let _: *mut Usize = core::intrinsics::transmute(my_int());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _: *mut Usize = core::mem::transmute(my_int());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: transmute from a `u8` to a `bool`
--> tests/ui/transmute.rs:114:28