`significant_drop_in_scrutinee`: Trigger lint only if lifetime allows early significant drop
I want to argue that the following code snippet should not trigger `significant_drop_in_scrutinee` (https://github.com/rust-lang/rust-clippy/issues/8987). The iterator holds a reference to the locked data, so it is expected that the mutex guard must be alive until the entire loop is finished.
```rust
use std::sync::Mutex;
fn main() {
let mutex_vec = Mutex::new(vec![1, 2, 3]);
for number in mutex_vec.lock().unwrap().iter() {
dbg!(number);
}
}
```
However, the lint should be triggered when we clone the vector. In this case, the iterator does not hold any reference to the locked data.
```diff
- for number in mutex_vec.lock().unwrap().iter() {
+ for number in mutex_vec.lock().unwrap().clone().iter() {
```
Unfortunately, it seems that regions on the types of local variables are mostly erased (`ReErased`) in the late lint pass. So it is hard to tell if the final expression has a lifetime relevant to the value with a significant drop.
In this PR, I try to make a best-effort guess based on the function signatures. To avoid false positives, no lint is issued if the result is uncertain. I'm not sure if this is acceptable or not, so any comments are welcome.
Fixes https://github.com/rust-lang/rust-clippy/issues/8987
changelog: [`significant_drop_in_scrutinee`]: Trigger lint only if lifetime allows early significant drop.
r? `@flip1995`
fulfill expectations in `check_unsafe_derive_deserialize`
The utility function `clippy_utils::fulfill_or_allowed` is not used because using it would require to move the check for allowed after the check iterating over all inherent impls of the type, doing possibly unnecessary work.
Instead, `is_lint_allowed` is called as before, but additionally, once certain that the lint should be emitted, `span_lint_hir_and_then` is called instead of `span_lint_and_help` to also fulfill expectations.
Note: as this is my first contribution, please feel free to nitpick or request changes. I am happy to adjust the implementation.
fixes: #12802
changelog: fulfill expectations in [`unsafe_derive_deserialize`]
Add new lint `while_float`
This PR adds a nursery lint that checks for while loops comparing floating point values.
changelog:
```
changelog: [`while_float`]: Checks for while loops comparing floating point values.
```
Fixes#758
This avoids event spans that would otherwise cause crashes, since an
End's span covers the range of the tag (which will be earlier than the
line break within the tag).
make sure the msrv for `const_raw_ptr_deref` is met when linting [`missing_const_for_fn`]
fixes: #8864
---
changelog: make sure the msrv for `const_ptr_deref` is met when linting [`missing_const_for_fn`]
less aggressive needless_borrows_for_generic_args
Current implementation looks for significant drops, that can change the behavior, but that's not enough - value might not have a `Drop` itself but one of its children might have it.
A good example is passing a reference to `PathBuf` to `std::fs::File::open`. There's no benefits to pass `PathBuf` by value, but since `clippy` can't see `Drop` on `Vec` several layers down it complains forcing pass by value and making it impossible to use the same name later.
New implementation only looks at copy values or values created in place so existing variable will never be moved but things that take a string reference created and value is created inplace `&"".to_owned()` will make it to suggest to use `"".to_owned()` still.
Fixes https://github.com/rust-lang/rust-clippy/issues/12454
changelog: [`needless_borrows_for_generic_args`]: avoid moving variables
improve [`match_same_arms`] messages, enable rustfix test
closes: #9251
don't worry about the commit size, most of them are generated
---
changelog: improve [`match_same_arms`] lint messages
`significant_drop_in_scrutinee`: Fix false positives due to false drops of place expressions
Place expressions do not really create temporaries, so they will not create significant drops. For example, the following code snippet is quite good (#8963):
```rust
fn main() {
let x = std::sync::Mutex::new(vec![1, 2, 3]);
let x_guard = x.lock().unwrap();
match x_guard[0] {
1 => println!("1!"),
x => println!("{x}"),
}
drop(x_guard); // Some "usage"
}
```
Also, the previous logic thinks that references like `&MutexGuard<_>`/`Ref<'_, MutexGuard<'_, _>>` have significant drops, which is simply not true, so it is fixed together in this PR.
Fixes https://github.com/rust-lang/rust-clippy/issues/8963
Fixes https://github.com/rust-lang/rust-clippy/issues/9072
changelog: [`significant_drop_in_scrutinee`]: Fix false positives due to false drops of place expressions.
r? `@blyxyas`
Handle `rustc_on_unimplemented` in duplicated_attributes
```rust
#[rustc_on_unimplemented(
on(
_Self = "&str",
label = "`a"
),
on(
_Self = "alloc::string::String",
label = "a"
),
)]
```
The lint treats this as a repetition because `rustc_on_unimplemented:🔛:label` appears twice, but that's ok.
Fixes#12619
changelog: [`duplicated_attributes`]: fix handling of `rustc_on_unimplemented`
Add new lint `doc_lazy_continuation`
changelog: [`doc_lazy_continuation`]: add lint that warns on so-called "lazy paragraph continuations"
This is a follow-up for https://github.com/rust-lang/rust/pull/121659, since most cases of unintended block quotes are lazy continuations. The lint is designed to be more generally useful than that, though, because it will also catch unintended list items and unintended block quotes that didn't coincidentally hit a pulldown-cmark bug.
The second commit is the result of running `cargo dev dogfood --fix`, and manually fixing anything that seems wrong. NOTE: this lint's suggestions should never change the parser's interpretation of the markdown, but in many cases, it seems that doc comments in clippy were written without regard for this feature of Markdown (which, I suppose, is why this lint should exist).
fix: use hir_with_context to produce correct snippets for assigning_clones
The `assigning_clones` lint is producing wrong output when the assignment is a macro call.
Since Applicability level `Unspecified` will never be changed inside `hir_with_applicability`, so it is safe here to replace `hir_with_applicability` with `hir_with_context` to generate snippets of the macro call instead of the expansion.
fixes#12776
changelog: [`assigning_clones`]: use `hir_with_context` to produce correct snippets
fix false positive in Issue/12098 because lack of consideration of mutable caller
fixes [Issue#12098](https://github.com/rust-lang/rust-clippy/issues/12098)
In issue#12098, the former code doesn't consider the caller for clone is mutable, and suggests to delete clone function.
In this change, we first get the inner caller requests for clone,
and if it's immutable, the following code will suggest deleting clone.
If it's mutable, the loop will check whether a borrow check violation exists,
if exists, the lint should not execute, and the function will directly return;
otherwise, the following code will handle this.
changelog: [`clippy::unnecessary_to_owned`]: fix false positive
This is a follow-up for https://github.com/rust-lang/rust/pull/121659,
since most cases of unintended block quotes are lazy continuations.
The lint is designed to be more generally useful than that, though,
because it will also catch unintended list items and unintended
block quotes that didn't coincidentally hit a pulldown-cmark bug.
Allow more attributes in `clippy::useless_attribute`
Fixes#12753Fixes#4467Fixes#11595Fixes#10878
changelog: [`useless_attribute`]: Attributes allowed on `use` items now include `ambiguous_glob_exports`, `hidden_glob_reexports`, `dead_code`, `unused_braces`, and `clippy::disallowed_types`.
Current implementation looks for significant drops, that can change the
behavior, but that's not enough - value might not have a Drop itself but
one of its children might have it.
A good example is passing a reference to `PathBuf` to `std::fs::File::open`.
There's no benefits to pass `PathBuf` by value, but since clippy can't
see `Drop` on `Vec` several layers down it complains forcing pass by
value and making it impossible to use the same name later.
New implementation only looks at copy values or values created inplace
so existing variable will never be moved but things that take a string
reference created and value is created inplace `&"".to_owned()` will
make it to suggest to use `"".to_owned()` still.
Fixes https://github.com/rust-lang/rust-clippy/issues/12454
Suggest collapsing nested or patterns if the MSRV allows it
Nested `or` patterns have been stable since 1.53, so we should be able to suggest `Some(1 | 2)` if the MSRV isn't set below that.
This change adds an msrv check and also moves it to `matches/mod.rs`, because it's also needed by `redundant_guards`.
changelog: [`collapsible_match`]: suggest collapsing nested or patterns if the MSRV allows it
