New lint: `match_wildcard_for_single_variants`
changelog: Added a new lint match_wildcard_for_single_variants to warn on enum matches where a wildcard is used to match a single variant
Closes#5556
Literal error reporting cleanup
While doing some performance work, I noticed some code duplication in `librustc_parser/lexer/mod.rs`, so I cleaned it up.
This PR is probably best reviewed commit by commit.
I'm not sure what the API stability practices for `librustc_lexer` are. Four public methods in `unescape.rs` can be removed, but two are used by clippy, so I left them in for now.
I could open a PR for Rust-Analyzer when this one lands.
But how do I open a PR for clippy? (Git submodules are frustrating to work with)
Reversed empty ranges
This lint checks range expressions with inverted limits which result in empty ranges. This includes also the ranges used to index slices.
The lint reverse_range_loop was covering iteration of reversed ranges in a for loop, which is a subset of what this new lint covers, so it has been removed. I'm not sure if that's the best choice. It would be doable to check in the new lint that we are not in the arguments of a for loop; I went for removing it because the logic was too similar to keep them separated.
changelog: Added reversed_empty_ranges lint that checks for ranges where the limits have been inverted, resulting in empty ranges. Removed reverse_range_loop which was covering a subset of the new lint.
Closes#4192Closes#96
Extend example for the `unneeded_field_pattern` lint
Current example is incorrect (or pseudo-code) because a struct name is omitted. I have used the code from the tests instead. Perhaps this example can be made less verbose, but I think it is more convenient to see a "real" code as an example.
---
changelog: extend example for the `unneeded_field_pattern` lint
Fix match on vec items: match on vec[..]
- Added new tests
- Fixed false positive when matching on full range, which will never panic
Closes#5551
changelog: fix match_on_vec_items when matching full range
Fix `unnecessary_unwrap` lint when checks are done in parameters
Fixes a false positive in `unnecessary_unwrap` lint when checks are done in macro parameters.
FIxes#5174
changelog: Fixes a false positive in `unnecessary_unwrap` lint when checks are done in macro parameters.
Fix FP on while-let-on-iterator
- fix `is_refutable` for slice patterns
- fix `is_refutable` for bindings
- add some TODO-s for cases, which can not be fixed easily
fixes#3780
changelog: fix FP on while-let-on-iterator for arrays and bindings
Implement the manual_non_exhaustive lint
Some implementation notes:
* Not providing automatic fixups because additional changes may be needed in other parts of the code, e.g. when constructing a struct.
* Even though the attribute is valid on enum variants, it's not possible to use the manual implementation of the pattern because the visibility is always public, so the lint ignores enum variants.
* Unit structs are also ignored, it's not possible to implement the pattern manually without fields.
* The attribute is not accepted in unions, so those are ignored too.
* Even though the original issue did not mention it, tuple structs are also linted because it's possible to apply the pattern manually.
changelog: Added the manual non-exhaustive implementation lint
Closes#2017
Fix the bugs of `manual_memcpy`, simplify the suggestion and refactor it
While I’m working on the long procrastinated work to expand `manual_memcpy`(#1670), I found a few minor bugs and probably unidiomatic or old coding style. There is a brief explanation of changes to the behaviour this PR will make below. And, I have a questoin: do I need to add tests for the first and second fixed bugs? I thought it might be too rare cases to include the tests for those. I added for the last one though.
* Bug fix
* It negates resulted offsets (`src/dst_offset`) when `offset` is subtraction by 0. This PR will remove any subtraction by 0 as a part of minification.
```rust
for i in 0..5 {
dst[i - 0] = src[i];
}
```
```diff
warning: it looks like you're manually copying between slices
--> src/main.rs:2:14
|
LL | for i in 0..5 {
- | ^^^^ help: try replacing the loop by: `dst[..-5].clone_from_slice(&src[..5])`
+ | ^^^^ help: try replacing the loop by: `dst[..5].clone_from_slice(&src[..5])`
|
```
* It prints `RangeTo` or `RangeFull` when both of `end` and `offset` are 0, which have different meaning. This PR will print 0. I could reject the cases `end` is 0, but I thought I won’t catch other cases `reverse_range_loop` will trigger, and it’s over to catch every such cases.
```rust
for i in 0..0 {
dst[i] = src[i];
}
```
```diff
warning: it looks like you're manually copying between slices
--> src/main.rs:2:14
|
LL | for i in 0..0 {
- | ^^^^ help: try replacing the loop by: `dst.clone_from_slice(&src[..])`
+ | ^^^^ help: try replacing the loop by: `dst[..0].clone_from_slice(&src[..0])`
|
```
* it prints four dots when `end` is `None`. This PR will ignore any `for` loops without `end` because a `for` loop that takes `RangeFrom` as its argument and contains indexing without the statements or the expressions that end loops such as `break` will definitely panic, and `manual_memcpy` should ignore the loops with such control flow.
```rust
fn manual_copy(src: &[u32], dst: &mut [u32]) {
for i in 0.. {
dst[i] = src[i];
}
}
```
```diff
-warning: it looks like you're manually copying between slices
- --> src/main.rs:2:14
- |
-LL | for i in 0.. {
- | ^^^ help: try replacing the loop by: `dst[....].clone_from_slice(&src[....])`
- |
```
* Simplification of the suggestion
* It prints 0 when `start` or `end` and `offset` are same (from #3323). This PR will use `RangeTo`
changelog: fixed the bugs of `manual_memcpy` and also simplify the suggestion.
