Open
Description
Using the following flags
--force-warn clippy::std-instead-of-core
this code:
#![deny(dangling_pointers_from_temporaries)]
#![feature(sync_unsafe_cell)]
use std::cell::{Cell, SyncUnsafeCell, UnsafeCell};
use std::ffi::{CStr, CString};
use std::mem::MaybeUninit;
struct AsPtrFake;
impl AsPtrFake {
fn as_ptr(&self) -> *const () {
std::ptr::null()
}
}
fn declval<T>() -> T {
loop {}
}
fn main() {
declval::<CString>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `CString` will be dropped
declval::<String>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `String` will be dropped
declval::<Vec<u8>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Vec<u8>` will be dropped
declval::<Box<CString>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<CString>` will be dropped
declval::<Box<[u8]>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<[u8]>` will be dropped
declval::<Box<str>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<str>` will be dropped
declval::<Box<CStr>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<CStr>` will be dropped
declval::<[u8; 10]>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `[u8; 10]` will be dropped
declval::<Box<[u8; 10]>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<[u8; 10]>` will be dropped
declval::<Box<Vec<u8>>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<Vec<u8>>` will be dropped
declval::<Box<String>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<String>` will be dropped
declval::<Box<Box<Box<Box<[u8]>>>>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<Box<Box<Box<[u8]>>>>` will be dropped
declval::<Cell<u8>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Cell<u8>` will be dropped
declval::<MaybeUninit<u8>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `MaybeUninit<u8>` will be dropped
declval::<Vec<AsPtrFake>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Vec<AsPtrFake>` will be dropped
declval::<UnsafeCell<u8>>().get();
//~^ ERROR a dangling pointer will be produced because the temporary `UnsafeCell<u8>` will be dropped
declval::<SyncUnsafeCell<u8>>().get();
//~^ ERROR a dangling pointer will be produced because the temporary `SyncUnsafeCell<u8>` will be dropped
declval::<Box<AsPtrFake>>().as_ptr();
declval::<AsPtrFake>().as_ptr();
}caused the following diagnostics:
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Checking _types v0.1.0 (/tmp/icemaker_global_tempdir.hTWDZB3NcvpG/icemaker_clippyfix_tempdir.V4DD5ifBcV5q/_types)
warning: used import from `std` instead of `core`
--> src/main.rs:4:5
|
4 | use std::cell::{Cell, SyncUnsafeCell, UnsafeCell};
| ^^^ help: consider importing the item from `core`: `core`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_core
= note: requested on the command line with `--force-warn clippy::std-instead-of-core`
warning: used import from `std` instead of `core`
--> src/main.rs:5:5
|
5 | use std::ffi::{CStr, CString};
| ^^^ help: consider importing the item from `core`: `core`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_core
warning: used import from `std` instead of `core`
--> src/main.rs:6:5
|
6 | use std::mem::MaybeUninit;
| ^^^ help: consider importing the item from `core`: `core`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_core
warning: used import from `std` instead of `core`
--> src/main.rs:12:9
|
12 | std::ptr::null()
| ^^^ help: consider importing the item from `core`: `core`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_core
warning: `_types` (bin "_types") generated 4 warnings (run `cargo clippy --fix --bin "_types"` to apply 4 suggestions)
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.56s
However after applying these diagnostics, the resulting code:
#![deny(dangling_pointers_from_temporaries)]
#![feature(sync_unsafe_cell)]
use core::cell::{Cell, SyncUnsafeCell, UnsafeCell};
use core::ffi::{CStr, CString};
use core::mem::MaybeUninit;
struct AsPtrFake;
impl AsPtrFake {
fn as_ptr(&self) -> *const () {
core::ptr::null()
}
}
fn declval<T>() -> T {
loop {}
}
fn main() {
declval::<CString>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `CString` will be dropped
declval::<String>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `String` will be dropped
declval::<Vec<u8>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Vec<u8>` will be dropped
declval::<Box<CString>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<CString>` will be dropped
declval::<Box<[u8]>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<[u8]>` will be dropped
declval::<Box<str>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<str>` will be dropped
declval::<Box<CStr>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<CStr>` will be dropped
declval::<[u8; 10]>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `[u8; 10]` will be dropped
declval::<Box<[u8; 10]>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<[u8; 10]>` will be dropped
declval::<Box<Vec<u8>>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<Vec<u8>>` will be dropped
declval::<Box<String>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<String>` will be dropped
declval::<Box<Box<Box<Box<[u8]>>>>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Box<Box<Box<Box<[u8]>>>>` will be dropped
declval::<Cell<u8>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Cell<u8>` will be dropped
declval::<MaybeUninit<u8>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `MaybeUninit<u8>` will be dropped
declval::<Vec<AsPtrFake>>().as_ptr();
//~^ ERROR a dangling pointer will be produced because the temporary `Vec<AsPtrFake>` will be dropped
declval::<UnsafeCell<u8>>().get();
//~^ ERROR a dangling pointer will be produced because the temporary `UnsafeCell<u8>` will be dropped
declval::<SyncUnsafeCell<u8>>().get();
//~^ ERROR a dangling pointer will be produced because the temporary `SyncUnsafeCell<u8>` will be dropped
declval::<Box<AsPtrFake>>().as_ptr();
declval::<AsPtrFake>().as_ptr();
}no longer compiled:
Checking _types v0.1.0 (/tmp/icemaker_global_tempdir.hTWDZB3NcvpG/icemaker_clippyfix_tempdir.V4DD5ifBcV5q/_types)
error[E0432]: unresolved import `core::ffi::CString`
--> src/main.rs:5:23
|
5 | use core::ffi::{CStr, CString};
| ^^^^^^^ no `CString` in `ffi`
|
= help: consider importing this struct instead:
std::ffi::CString
For more information about this error, try `rustc --explain E0432`.
error: could not compile `_types` (bin "_types" test) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `_types` (bin "_types") due to 1 previous error
Version:
rustc 1.90.0-nightly (8cf5fad73 2025-06-25)
binary: rustc
commit-hash: 8cf5fad73d4e8f41863ecc3bcfa114eabc951faa
commit-date: 2025-06-25
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.7