rust-lang / rust-lang/rust-clippy
or_fun_call suggests invalid code by removing type information
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@J-ZhengLi is already working on this.
Since Jul 19, 2024.
C-bug
I-suggestion-causes-error
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Description
Summary
Clippy suggests/auto-fixes to invalid code for lint or_fun_call. It's invalid if the inserted value contains type information that is not available elsewhere.
https://rust-lang.github.io/rust-clippy/master/#or_fun_call
Reproducer
Minimal example (working minimal repro available to run at https://github.com/tommilligan/rust-clippy-repro-9790):
use std::collections::HashMap;
pub fn example() {
let mut parent = HashMap::new();
let grandchild = parent.entry(2).or_insert(Vec::new());
grandchild.push(-1);
}
Output:
warning: failed to automatically apply fixes suggested by rustc to crate `clippy_new_after_insert`
after fixes were automatically applied the compiler reported errors within these files:
* src/lib.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[E0282]: type annotations needed for `&mut V`
--> src/lib.rs:5:9
|
5 | let grandchild = parent.entry(2).or_default();
| ^^^^^^^^^^
6 | grandchild.push(-1);
| ---- type must be known at this point
|
help: consider giving `grandchild` an explicit type, where the type for type parameter `V` is specified
|
5 | let grandchild: &mut V = parent.entry(2).or_default();
| ++++++++
error: aborting due to previous error
For more information about this error, try `rustc --explain E0282`.
Original diagnostics will follow.
warning: use of `or_insert` followed by a call to `new`
--> src/lib.rs:5:38
|
5 | let grandchild = parent.entry(2).or_insert(Vec::new());
| ^^^^^^^^^^^^^^^^^^^^^ help: try this: `or_default()`
|
= note: `#[warn(clippy::or_fun_call)]` on by default
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#or_fun_call
Version
rustc 1.65.0 (897e37553 2022-11-02)
binary: rustc
commit-hash: 897e37553bba8b42751c67658967889d11ecd120
commit-date: 2022-11-02
host: x86_64-unknown-linux-gnu
release: 1.65.0
LLVM version: 15.0.0
Additional Labels
@rustbot label +I-suggestion-causes-error
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