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Unrolled build for rust-lang#117824
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Rollup merge of rust-lang#117824 - WaffleLapkin:ptr_from_ref_stab, r=dtolnay

Stabilize `ptr::{from_ref, from_mut}`

I propose to stabilize the following APIs:

```rust
// mod core::ptr

pub const fn from_ref<T: ?Sized>(r: &T) -> *const T;
pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T;
```

Tracking issue: rust-lang#106116

---

``@RalfJung`` what do you think we should do with `from_mut`? Stabilize it as const, given that you can't call it anyway (no way to get `&mut` in `const fn`)? Defer stabilizing it as const leaving the same issue/feature? Change issue/feature? Change issue/feature to the "`&mut` in const fn" one?
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@rust-timer
rust-timer authored Dec 15, 2023
2 parents 3f39cae + b863e9b commit 4cf5fc9
Showing 7 changed files with 74 additions and 77 deletions.
7 changes: 5 additions & 2 deletions library/core/src/ptr/mod.rs
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Original file line number Diff line number Diff line change
@@ -720,7 +720,8 @@ where
/// type or mutability, in particular if the code is refactored.
#[inline(always)]
#[must_use]
#[unstable(feature = "ptr_from_ref", issue = "106116")]
#[stable(feature = "ptr_from_ref", since = "CURRENT_RUSTC_VERSION")]
#[rustc_const_stable(feature = "ptr_from_ref", since = "CURRENT_RUSTC_VERSION")]
#[rustc_never_returns_null_ptr]
#[rustc_diagnostic_item = "ptr_from_ref"]
pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
@@ -733,7 +734,9 @@ pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
/// type or mutability, in particular if the code is refactored.
#[inline(always)]
#[must_use]
#[unstable(feature = "ptr_from_ref", issue = "106116")]
#[stable(feature = "ptr_from_ref", since = "CURRENT_RUSTC_VERSION")]
#[rustc_const_stable(feature = "ptr_from_ref", since = "CURRENT_RUSTC_VERSION")]
#[rustc_allow_const_fn_unstable(const_mut_refs)]
#[rustc_never_returns_null_ptr]
pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
r
1 change: 0 additions & 1 deletion library/std/src/lib.rs
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Original file line number Diff line number Diff line change
@@ -338,7 +338,6 @@
#![feature(portable_simd)]
#![feature(prelude_2024)]
#![feature(ptr_as_uninit)]
#![feature(ptr_from_ref)]
#![feature(raw_os_nonzero)]
#![feature(round_ties_even)]
#![feature(slice_internals)]
2 changes: 0 additions & 2 deletions tests/ui/lint/ptr_null_checks.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,5 @@
// check-pass

#![feature(ptr_from_ref)]

use std::ptr;

extern "C" fn c_fn() {}
54 changes: 27 additions & 27 deletions tests/ui/lint/ptr_null_checks.stderr
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:14:8
--> $DIR/ptr_null_checks.rs:12:8
|
LL | if (fn_ptr as *mut ()).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^
@@ -10,7 +10,7 @@ LL | if (fn_ptr as *mut ()).is_null() {}
= note: `#[warn(useless_ptr_null_checks)]` on by default

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:16:8
--> $DIR/ptr_null_checks.rs:14:8
|
LL | if (fn_ptr as *const u8).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^
@@ -20,7 +20,7 @@ LL | if (fn_ptr as *const u8).is_null() {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:18:8
--> $DIR/ptr_null_checks.rs:16:8
|
LL | if (fn_ptr as *const ()) == std::ptr::null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -30,7 +30,7 @@ LL | if (fn_ptr as *const ()) == std::ptr::null() {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:20:8
--> $DIR/ptr_null_checks.rs:18:8
|
LL | if (fn_ptr as *mut ()) == std::ptr::null_mut() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -40,7 +40,7 @@ LL | if (fn_ptr as *mut ()) == std::ptr::null_mut() {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:22:8
--> $DIR/ptr_null_checks.rs:20:8
|
LL | if (fn_ptr as *const ()) == (0 as *const ()) {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -50,7 +50,7 @@ LL | if (fn_ptr as *const ()) == (0 as *const ()) {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:24:8
--> $DIR/ptr_null_checks.rs:22:8
|
LL | if <*const _>::is_null(fn_ptr as *const ()) {}
| ^^^^^^^^^^^^^^^^^^^^------^^^^^^^^^^^^^^
@@ -60,7 +60,7 @@ LL | if <*const _>::is_null(fn_ptr as *const ()) {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:26:8
--> $DIR/ptr_null_checks.rs:24:8
|
LL | if (fn_ptr as *mut fn() as *const fn() as *const ()).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -70,7 +70,7 @@ LL | if (fn_ptr as *mut fn() as *const fn() as *const ()).is_null() {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:28:8
--> $DIR/ptr_null_checks.rs:26:8
|
LL | if (fn_ptr as *mut fn() as *const fn()).cast_mut().is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -80,7 +80,7 @@ LL | if (fn_ptr as *mut fn() as *const fn()).cast_mut().is_null() {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:30:8
--> $DIR/ptr_null_checks.rs:28:8
|
LL | if ((fn_ptr as *mut fn()).cast() as *const fn()).cast_mut().is_null() {}
| ^^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -90,7 +90,7 @@ LL | if ((fn_ptr as *mut fn()).cast() as *const fn()).cast_mut().is_null() {
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:32:8
--> $DIR/ptr_null_checks.rs:30:8
|
LL | if (fn_ptr as fn() as *const ()).is_null() {}
| ^--------------^^^^^^^^^^^^^^^^^^^^^^^^
@@ -100,7 +100,7 @@ LL | if (fn_ptr as fn() as *const ()).is_null() {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:34:8
--> $DIR/ptr_null_checks.rs:32:8
|
LL | if (c_fn as *const fn()).is_null() {}
| ^----^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -110,117 +110,117 @@ LL | if (c_fn as *const fn()).is_null() {}
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:38:8
--> $DIR/ptr_null_checks.rs:36:8
|
LL | if (&mut 8 as *mut i32).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&mut i32`

warning: returned pointer of `from_mut` call is never null, so checking it for null will always return false
--> $DIR/ptr_null_checks.rs:40:8
--> $DIR/ptr_null_checks.rs:38:8
|
LL | if ptr::from_mut(&mut 8).is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:42:8
--> $DIR/ptr_null_checks.rs:40:8
|
LL | if (&8 as *const i32).is_null() {}
| ^--^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`

warning: returned pointer of `from_ref` call is never null, so checking it for null will always return false
--> $DIR/ptr_null_checks.rs:44:8
--> $DIR/ptr_null_checks.rs:42:8
|
LL | if ptr::from_ref(&8).is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: returned pointer of `from_ref` call is never null, so checking it for null will always return false
--> $DIR/ptr_null_checks.rs:46:8
--> $DIR/ptr_null_checks.rs:44:8
|
LL | if ptr::from_ref(&8).cast_mut().is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: returned pointer of `from_ref` call is never null, so checking it for null will always return false
--> $DIR/ptr_null_checks.rs:48:8
--> $DIR/ptr_null_checks.rs:46:8
|
LL | if (ptr::from_ref(&8).cast_mut() as *mut i32).is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:50:8
--> $DIR/ptr_null_checks.rs:48:8
|
LL | if (&8 as *const i32) == std::ptr::null() {}
| ^--^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:53:8
--> $DIR/ptr_null_checks.rs:51:8
|
LL | if (ref_num as *const i32) == std::ptr::null() {}
| ^-------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:55:8
--> $DIR/ptr_null_checks.rs:53:8
|
LL | if (b"\0" as *const u8).is_null() {}
| ^-----^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&[u8; 1]`

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:57:8
--> $DIR/ptr_null_checks.rs:55:8
|
LL | if ("aa" as *const str).is_null() {}
| ^----^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&str`

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:59:8
--> $DIR/ptr_null_checks.rs:57:8
|
LL | if (&[1, 2] as *const i32).is_null() {}
| ^-------^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&[i32; 2]`

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:61:8
--> $DIR/ptr_null_checks.rs:59:8
|
LL | if (&mut [1, 2] as *mut i32) == std::ptr::null_mut() {}
| ^-----------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&mut [i32; 2]`

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:63:8
--> $DIR/ptr_null_checks.rs:61:8
|
LL | if (static_i32() as *const i32).is_null() {}
| ^------------^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`

warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:65:8
--> $DIR/ptr_null_checks.rs:63:8
|
LL | if (&*{ static_i32() } as *const i32).is_null() {}
| ^------------------^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`

warning: returned pointer of `as_ptr` call is never null, so checking it for null will always return false
--> $DIR/ptr_null_checks.rs:69:8
--> $DIR/ptr_null_checks.rs:67:8
|
LL | if ptr::NonNull::new(&mut 8).unwrap().as_ptr().is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: returned pointer of `as_ptr` call is never null, so checking it for null will always return false
--> $DIR/ptr_null_checks.rs:71:8
--> $DIR/ptr_null_checks.rs:69:8
|
LL | if ptr::NonNull::<u8>::dangling().as_ptr().is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2 changes: 0 additions & 2 deletions tests/ui/lint/reference_casting.rs
View file
Original file line number Diff line number Diff line change
@@ -1,7 +1,5 @@
// check-fail

#![feature(ptr_from_ref)]

extern "C" {
// N.B., mutability can be easily incorrect in FFI calls -- as
// in C, the default is mutable pointers.
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