Fix clippy::collapsible_match with let expressions
This fixes rust-lang/rust-clippy#7575 which is a regression from #80357. I am fixing the bug here instead of in the clippy repo (if that's okay) because a) the regression has not been synced yet and b) I would like to land the fix on nightly asap.
The fix is basically to re-generalize `match` and `if let` for the lint implementation (they were split because `if let` no longer desugars to `match` in the HIR).
Also fixesrust-lang/rust-clippy#7586 and fixesrust-lang/rust-clippy#7591
cc `@rust-lang/clippy`
`@xFrednet` do you want to review this?
New lint `manual_split_once`
This is a WIP because it still needs to recognize more patterns. Currently handles:
```rust
s.splitn(2, ' ').next();
s.splitn(2, ' ').nth(0)
s.splitn(2, ' ').nth(1);
s.splitn(2, ' ').skip(0).next();
s.splitn(2, ' ').skip(1).next();
s.splitn(2, ' ').next_tuple(); // from itertools
// as well as `unwrap()` and `?` forms
```
Still to do:
```rust
let mut iter = s.splitn(2, ' ');
(iter.next().unwrap(), iter.next()?)
let mut iter = s.splitn(2, ' ');
let key = iter.next().unwrap();
let value = iter.next()?;
```
Suggestions on other patterns to check for would be useful. I've done a search on github for uses of `splitn`. Still have yet to actually look through the results.
There's also the question of whether the lint shouold trigger on all uses of `splitn` with two values, or only on recognized usages. The former could have false positives where it couldn't be replaced, but I'm not sure how common that would be.
changelog: Add lint `manual_split_once`
Small documentation update for the new metadata_collector
Just small documentation updates after the merge of the new metadata collection. I'm also here to deliver on the promised fairy tale:
*Once upon a time, there was a world with many languages. One of the oldest was C a very versatile language that gave great power for the cost of great complexity and manual work. C was so powerful that it was able to create new languages. There is Java a versatile language often used by companies and in formal settings. Python that focused on readability and rapid prototyping capabilities. JavaScript which has some interesting edge cases but was still loved and widely used in the world. Together they build the foundation of our world and continue to shape the interactions between kingdoms worldwide.*
*C ruled as the king of Linux and other operating systems alongside the Queen C++. Together they were powerful leaders, in fact so powerful that they have been ruling this world for over 49 years. They remain happy together and loved by the community. However, with great power comes great responsibility! The two of them have a dark secret. To tell the truth, they sometimes suffer from memory loss and even worse in some instances from race conditions.*
*A mystical creature called Firefox lead to the creation of Mozilla, a global organization fighting for privacy and for their market share in the browser marked. As part of this fight, they started to modify parts of Firefox and eventually created Servo. A completely new creature with a new language called Rust. This new form of communication was focussed on correctness, speed and a new model of memory management.*
*Rust grew up over several years with modification to syntax, content among other things. Finally, in 2015 Rust has reached adulthood which enabled it to take part in the global discourse and shape the future of our world. Some even say that this was the start of a new area withing language design.*
*Rust had already started to build its kingdom and was now the head of a complete organization, with teams being in charge of individual tools used for further development. One team focussing on further improving Rust when it comes to complexity, style and performance was **The Clippy Team**. Its members were a friendly bunch, with mages and wizards among them.*
*With the goal of giving more power to Rust, they identified a Python tool inside Clippy that could be rewritten. This led to the creating of the **Metadata collection monster**. This monster soon replaced the old Python tool and allowed for new creative additions inside Clippy's lint list. With the eradication of the old tool, there came a possibility to update the configuration documentation to span over a lager area. This was done, but some doc comments remained until now in memory of the old tool. This is now the PR that removes these doc comments.*
---
I have to stop now, this already took way longer than the actual changes. It probably also contains some spelling mistakes, but oh well. I hope you get the gist of it 🙃.
---
r? `@camsteffen`
changelog: none
* `break` and `continue` statments local to the would-be closure are allowed
* don't lint in const contexts
* don't lint when yield expressions are used
* don't lint when the captures made by the would-be closure conflict with the other branch
* don't lint when a field of a local is used when the type could be pontentially moved from
* in some cases, don't lint when scrutinee expression conflicts with the captures of the would-be closure
Check expr usage for `manual_flatten`
Fixes#6784Fixes#7538
`manual_flatten` should not trigger when `if let` match expression will be used.
changelog: [`manual_flatten`] checks for expr usage after `if let`
Uplift the invalid_atomic_ordering lint from clippy to rustc
This is mostly just a rebase of https://github.com/rust-lang/rust/pull/79654; I've copy/pasted the text from that PR below.
r? `@lcnr` since you reviewed the last one, but feel free to reassign.
---
This is an implementation of https://github.com/rust-lang/compiler-team/issues/390.
As mentioned, in general this turns an unconditional runtime panic into a (compile time) lint failure. It has no false positives, and the only false negatives I'm aware of are if `Ordering` isn't specified directly and is comes from an argument/constant/whatever.
As a result of it having no false positives, and the alternative always being strictly wrong, it's on as deny by default. This seems right.
In the [zulip stream](https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/Uplift.20the.20.60invalid_atomic_ordering.60.20lint.20from.20clippy/near/218483957) `@joshtriplett` suggested that lang team should FCP this before landing it. Perhaps libs team cares too?
---
Some notes on the code for reviewers / others below
## Changes from clippy
The code is changed from [the implementation in clippy](68cf94f6a6/clippy_lints/src/atomic_ordering.rs) in the following ways:
1. Uses `Symbols` and `rustc_diagnostic_item`s instead of string literals.
- It's possible I should have just invoked Symbol::intern for some of these instead? Seems better to use symbol, but it did require adding several.
2. The functions are moved to static methods inside the lint struct, as a way to namespace them.
- There's a lot of other code in that file — which I picked as the location for this lint because `@jyn514` told me that seemed reasonable.
3. Supports unstable AtomicU128/AtomicI128.
- I did this because it was almost easier to support them than not — not supporting them would have (ideally) required finding a way not to give them a `rustc_diagnostic_item`, which would have complicated an already big macro.
- These don't have tests since I wasn't sure if/how I should make tests conditional on whether or not the target has the atomic... This is to a certain extent an issue of 64bit atomics too, but 128-bit atomics are much less common. Regardless, the existing tests should be *more* than thorough enough here.
4. Minor changes like:
- grammar tweaks ("loads cannot have `Release` **and** `AcqRel` ordering" => "loads cannot have `Release` **or** `AcqRel` ordering")
- function renames (`match_ordering_def_path` => `matches_ordering_def_path`),
- avoiding clippy-specific helper methods that don't exist in rustc_lint and didn't seem worth adding for this case (for example `cx.struct_span_lint` vs clippy's `span_lint_and_help` helper).
## Potential issues
(This is just about the code in this PR, not conceptual issues with the lint or anything)
1. I'm not sure if I should have used a diagnostic item for `Ordering` and its variants (I couldn't figure out how really, so if I should do this some pointers would be appreciated).
- It seems possible that failing to do this might possibly mean there are more cases this lint would miss, but I don't really know how `match_def_path` works and if it has any pitfalls like that, so maybe not.
2. I *think* I deprecated the lint in clippy (CC `@flip1995` who asked to be notified about clippy changes in the future in [this comment](https://github.com/rust-lang/rust/pull/75671#issuecomment-718731659)) but I'm not sure if I need to do anything else there.
- I'm kind of hoping CI will catch if I missed anything, since `x.py test src/tools/clippy` fails with a lot of errors with and without my changes (and is probably a nonsense command regardless). Running `cargo test` from src/tools/clippy also fails with unrelated errors that seem like refactorings that didnt update clippy? So, honestly no clue.
3. I wasn't sure if the description/example I gave good. Hopefully it is. The example is less thorough than the one from clippy here: https://rust-lang.github.io/rust-clippy/master/index.html#invalid_atomic_ordering. Let me know if/how I should change it if it needs changing.
4. It pulls in the `if_chain` crate. This crate was already used in clippy, and seems like it's used elsewhere in rustc, but I'm willing to rewrite it to not use this if needed (I'd prefer not to, all things being equal).
- Deprecate clippy::invalid_atomic_ordering
- Use rustc_diagnostic_item for the orderings in the invalid_atomic_ordering lint
- Reduce code duplication
- Give up on making enum variants diagnostic items and just look for
`Ordering` instead
I ran into tons of trouble with this because apparently the change to
store HIR attrs in a side table also gave the DefIds of the
constructor instead of the variant itself. So I had to change
`matches_ordering` to also check the grandparent of the defid as well.
- Rename `atomic_ordering_x` symbols to just the name of the variant
- Fix typos in checks - there were a few places that said "may not be
Release" in the diagnostic but actually checked for SeqCst in the lint.
- Make constant items const
- Use fewer diagnostic items
- Only look at arguments after making sure the method matches
This prevents an ICE when there aren't enough arguments.
- Ignore trait methods
- Only check Ctors instead of going through `qpath_res`
The functions take values, so this couldn't ever be anything else.
- Add if_chain to allowed dependencies
- Fix grammar
- Remove unnecessary allow
Manual map 7413
fixes: #7413
This only fixes the specific problem from #7413, not the general case. The full fix requires interacting with the borrow checker to determine the lifetime of all the borrows made in the function. I'll open an issue about it later.
changelog: Don't suggest using `map` when the option is borrowed in the match, and also consumed in the arm.
changelog: Locals declared within the would-be closure will not prevent the closure from being suggested in `manual_map` and `map_entry`
lintcheck always copies in a fresh crate when provided with a crate path
changelog: none
When lintcheck is run on local crates it copies the crate to `target/lintcheck/sources/crate_name` on the first run only.
Then in subsequent runs of lintcheck it reuses this same copy.
This caching behaviour makes sense when dealing with immutable crates.io releases and git commits.
However it is quite surprising that the changes to my local crate are not used when I run lintcheck.
To fix this I removed the copy, instead clippy runs directly off the provided crate folder.
I have tested this and have not observed any negative effects from doing this.
But maybe i'm missing something as im not familiar with clippy!
Alternatively we could make it copy the entire crate every run, but that seems problematic to me as multi-gigabyte target folders will take a long time to copy and wear down SSDs for developers who frequently run lintcheck.
Downgrade option_if_let_else to nursery
I believe that this lint's loose understanding of ownership (#5822, #6737) makes it unsuitable to be enabled by default in its current state, even as a pedantic lint.
Additionally the lint has known problems with type inference (#6137), though I may be willing to consider this a non-blocker in isolation if it weren't for the ownership false positives.
A fourth false positive involving const fn: #7567.
But on top of these, for me the biggest issue is I basically fully agree with https://github.com/rust-lang/rust-clippy/issues/6137#issuecomment-705605688. In my experience this lint universally makes code worse even when the resulting code does compile.
---
changelog: remove [`option_if_let_else`] from default set of enabled lints
* Captures by sub closures are now considered
* Copy types are correctly borrowed by reference when their value is used
* Fields are no longer automatically borrowed by value
* Bindings in `match` and `let` patterns are now checked to determine how a local is captured
Use `avoid-breaking-exported-api` configuration in types module
This PR empowers our lovely `avoid-breaking-exported-api` configuration value to also influence the emission of lints inside the `types` module.
(That's pretty much it, not really a change worthy of writing a fairy tale about. Don't get me wrong, I would love to write a short one, but I sadly need to study now).
---
Closes: rust-lang/rust-clippy#7489
changelog: The `avoid-breaking-exported-api` configuration now also works for [`box_vec`], [`redundant_allocation`], [`rc_buffer`], [`vec_box`], [`option_option`], [`linkedlist`], [`rc_mutex`]
changelog: [`rc_mutex`]: update the lint message to comply with the normal format
---
r? `@camsteffen,` as you implemented the configuration value
cc: `@flip1995,` as we've discussed this change in rust-lang/rust-clippy#7308
Link to edition guide instead of issues for 2021 lints.
This changes the 2021 lints to not link to github issues, but to the edition guide instead.
Fixes #86996
Add `unwrap_or_else_default` lint
---
*Please write a short comment explaining your change (or "none" for internal only changes)*
changelog: Add a new [`unwrap_or_else_default`] style lint. This will catch `unwrap_or_else(Default::default)` on Result and Option and suggest `unwrap_or_default()` instead.
