The lint used to check for patterns looking like:
```rs
for (_, x) in some_iter.enumerate() {
// Index is ignored
}
```
This commit further checks for chained method calls constructs where we
can detect that the index is unused. Currently, this checks only for the
following patterns:
```rs
some_iter.enumerate().map_function(|(_, x)| ..)
let x = some_iter.enumerate();
x.map_function(|(_, x)| ..)
```
where `map_function` is one of `all`, `any`, `filter_map`, `find_map`,
`flat_map`, `for_each` or `map`.
Fixes#12411.
lint when calling the blanket `Into` impl from a `From` impl
Closes#11150
```
warning: function cannot return without recursing
--> x.rs:9:9
|
9 | / fn from(value: f32) -> Self {
10 | | value.into()
11 | | }
| |_________^
|
note: recursive call site
--> x.rs:10:13
|
10 | value.into()
| ^^^^^^^^^^^^
```
I'm also thinking that we can probably generalize this lint to #11032 at some point (instead of hardcoding a bunch of impls), like how rustc's `unconditional_recursion` works, at least up to one indirect call, but this still seems useful for now :)
I've also noticed that we use `fn_def_id` in a bunch of lints and then try to get the node args of the call in a separate step, so I made a helper function that does both in one. I intend to refactor a bunch of uses of `fn_def_id` to use this later
I can add more test cases, but this is already using much of the same logic that exists for the other impls that this lint looks for (e.g. making sure that there are no conditional returns).
changelog: [`unconditional_recursion`]: emit a warning inside of `From::from` when unconditionally calling the blanket `.into()` impl
[`cast_lossless`]: Suggest type alias instead of the aliased type
Fixes#11285
Still an issue with the "from" side, i.e., `I8::from(1) as I64` shows as `i8 to I64`, but this should be ok. Not possible to reliably fix currently anyway.
changelog: [`cast_lossless`]: Suggest type alias instead of the aliased type
chore: fix some typos
Thank you for making Clippy better!
We're collecting our changelog from pull request descriptions.
If your PR only includes internal changes, you can just write
`changelog: none`. Otherwise, please write a short comment
explaining your change.
It's also helpful for us that the lint name is put within backticks (`` ` ` ``),
and then encapsulated by square brackets (`[]`), for example:
```
changelog: [`lint_name`]: your change
```
If your PR fixes an issue, you can add `fixes #issue_number` into this
PR description. This way the issue will be automatically closed when
your PR is merged.
If you added a new lint, here's a checklist for things that will be
checked during review or continuous integration.
- \[x] Followed [lint naming conventions][lint_naming]
- \[ ] Added passing UI tests (including committed `.stderr` file)
- \[ ] `cargo test` passes locally
- \[ ] Executed `cargo dev update_lints`
- \[ ] Added lint documentation
- \[x] Run `cargo dev fmt`
[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
Note that you can skip the above if you are just opening a WIP PR in
order to get feedback.
Delete this line and everything above before opening your PR.
---
*Please write a short comment explaining your change (or "none" for internal only changes)*
changelog:
Move `iter_nth` to `style`, add machine applicable suggestion
There's no `O(n)` involved with `.iter().nth()` on the linted types since the iterator implementations provide `nth` and/or `advance_by` that operate in `O(1)`
For slice iterators the codegen is equivalent, `VecDeque`'s iterator seems to codegen differently but that doesn't seem significant enough to keep it as a perf lint
changelog: [`iter_nth`] Move to `style`
r? `@flip1995`
Fix typo in section '6.10. Macro Expansions' of the Clippy Book
Under the "Span.ctxt method" heading in *Section 6.10. Macro Expansions* of the *Clippy Book*, the type returned by the
`Span::ctxt` method is listed as `SpanContext`. The correct type name should be `SyntaxContext`.
---
changelog: Fixed typo in "Section 6.10. Macro Expansions" of the Clippy Book. `SpanContext` changed to `SyntaxContext`.
[`manual_retain`]: Fix duplicate diagnostics
Relates to: #12379
The first lint guard executed in `LateLintPass::check_expr` was testing if the parent was of type `ExprKind::Assign`. This meant the lint emitted on both sides of the assignment operator when `check_expr` is called on either `Expr`. The guard in the fix only lints once when the `Expr` is of kind `Assign`.
changelog: Fix duplicate lint diagnostic emission from [`manual_retain`]
Add new `duplicated_attributes` lint
It's a lint idea that `@llogiq` gave me while reviewing another PR.
There are some limitations, in particular for the "output". Initially I wanted to make it possible for directly lint against the whole attribute if its parts were all duplicated, but then I realized that the output would be chaotic if the duplicates were coming from different attributes, so I preferred to go to the simplest way and simply emit a warning for each entry. Not the best, but makes the implementation much easier.
Another limitation is that `cfg_attr` would be a bit more tricky to implement because we need to check if two `cfg` sets are exactly the same. I added a FIXME and will likely come back to it later.
And finally, I updated the `cargo dev update_lints` command because the generated `tests/ui/rename.rs` file was emitting the `duplicated_attributes` lint, so I allowed this lint inside it to prevent it from working.
changelog: Add new `duplicated_attributes` lint
Fix dependency specifications
As Clippy lacks `Cargo.lock`, it makes sense to test its dependency specifications with [direct-minimal-versions](https://doc.rust-lang.org/cargo/reference/unstable.html#direct-minimal-versions). This can be done with the following addition to `.cargo/config.toml`.
```toml
[unstable]
direct-minimal-versions = true
```
* `tempfile` 3.3 is required by `clippy_lints`.
* `regex` 1.5.5 is required by `ui_test` 0.22.2.
* `quote` 1.0.25 is required by `syn` 2.0.0.
* `serde` 1.0.145 is required by `toml` 0.7.3.
changelog: none
[`single_match`]: Fix duplicate diagnostics
Relates to #12379
edit two test file
`tests/ui/single_match_else.rs`
`tests/ui/single_match.rs`
those two test file point to the same lint
---
changelog: [`single_match`] Fix duplicate diagnostics
[`seek_from_current`]: readability improvements
fixes#12457.
---
*Please write a short comment explaining your change (or "none" for internal only changes)*
changelog: [`seek_from_current`]: readability improvements
add documentation to the `span_lint_hir` functions
As far as I could tell, these weren't documented anywhere, and since this is sometimes needed over `span_lint` for `#[allow]` attrs to work, I thought I would add a little bit of documentation.
When I started with clippy development, I also had no idea what these functions were for.
changelog: none
Add new `manual_unwrap_or_default` lint
This adds a new lint checking if a `match` or a `if let` can be replaced with `unwrap_or_default`.
----
changelog: Add new [`manual_unwrap_or_default`] lint
Distinguish between library and lang UB in assert_unsafe_precondition
As described in https://github.com/rust-lang/rust/pull/121583#issuecomment-1963168186, `assert_unsafe_precondition` now explicitly distinguishes between language UB (conditions we explicitly optimize on) and library UB (things we document you shouldn't do, and maybe some library internals assume you don't do).
`debug_assert_nounwind` was originally added to avoid the "only at runtime" aspect of `assert_unsafe_precondition`. Since then the difference between the macros has gotten muddied. This totally revamps the situation.
Now _all_ preconditions shall be checked with `assert_unsafe_precondition`. If you have a precondition that's only checkable at runtime, do a `const_eval_select` hack, as done in this PR.
r? RalfJung
