rust-lang / rust-lang/rust-clippy
Clippy Error during auto fix
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C-bug
I-suggestion-causes-error
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Description
Clippy reported error during auto fix
❯ cargo clippy --workspace --all-features --fix --allow-dirty --broken-code -- -D clippy::all -D clippy::pedantic -D clippy::nursery -D clippy::cargo
Checking ril v0.1.0 (C:\Users\alvin\OneDrive\Desktop\repos\ril)
warning: failed to automatically apply fixes suggested by rustc to crate `ril`
after fixes were automatically applied the compiler reported errors within these files:
* src\encode.rs
This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag
The following errors were reported:
error[E0699]: the type of this value must be known to call a method on a raw pointer on it
--> src\encode.rs:55:37
|
55 | unsafe { (data as *const _).cast::<T>().read() }
| ^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0699`.
Original diagnostics will follow.
error[E0699]: the type of this value must be known to call a method on a raw pointer on it
--> src\encode.rs:55:37
|
55 | unsafe { (data as *const _).cast::<T>().read() }
| ^^^^
For more information about this error, try `rustc --explain E0699`.
error: could not compile `ril` due to previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `ril` due to previous error
Original code is
unsafe { (data as *const _ as *const T).read() }
Clippy attempted to change it to
unsafe { (data as *const _).cast::<T>().read() }
which leads to an error
Note: data is &[u8]
rustc --version --verbose
rustc 1.64.0-nightly (7b46aa594 2022-07-05)
binary: rustc
commit-hash: 7b46aa594c4bdc507fbd904b6777ca30c37a9209
commit-date: 2022-07-05
host: x86_64-pc-windows-msvc
release: 1.64.0-nightly
LLVM version: 14.0.6
The lint that likely caused it
error: `as` casting between raw pointers without changing its mutability
--> src\encode.rs:55:18
|
55 | unsafe { (data as *const _ as *const T).read() }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try `pointer::cast`, a safer alternative: `(data as *const _).cast::<T>()`
|
= note: `-D clippy::ptr-as-ptr` implied by `-D clippy::pedantic`
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the issue with the provided cargo clippy command and inspect src/encode.rs at line 55, focusing on the ptr-as-ptr suggestion. Done means the automatic fix no longer leaves the crate with E0699 and the workspace check completes successfully.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 45/100