rust-lang / rust-lang/rust-clippy
Incorrect fix: immediately dereferencing a reference to a literal as a place expression.
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C-bug
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Description
Summary
This corner case triggers an incorrect fix suggestion, leading to a compilation error.
Reproducer
main.rs
fn main() {
*&mut 4 = 5; // /!\ immediately dereferencing a reference
// ^^^^^^^ help: try: `4`
}
@Kyuuhachi Assigns to a temporary that is then dropped [1]
$ cargo clippy --fix --allow-dirty --allow-no-vcs
Checking rust_test v0.1.0 (./tests/rust)
warning: failed to automatically apply fixes suggested by rustc to crate `rust_test`
after fixes were automatically applied the compiler reported errors within these files:
* src/main.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-clippy/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[E0070]: invalid left-hand side of assignment
--> src/main.rs:2:7
|
2 | 4 = 5;
| - ^
| |
| cannot assign to this expression
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0070`.
Original diagnostics will follow.
Version
$ rustc -Vv
rustc 1.83.0-nightly (f79a912d9 2024-09-18)
binary: rustc
commit-hash: f79a912d9edc3ad4db910c0e93672ed5c65133fa
commit-date: 2024-09-18
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0
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
Start with the main.rs reproducer and run cargo clippy --fix using the shown command and rustc version. Check that the suggested replacement for immediately dereferencing a reference to a literal no longer produces the invalid assignment error E0070, and confirm the fix does not leave compilation errors.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100