option_if_let_else - distinguish pure from impure else expressions
Addresses partially #5821.
changelog: improve the lint `option_if_let_else`. Suggest `map_or` or `map_or_else` based on the else expression purity.
Extend invalid_atomic_ordering for compare_exchange{,_weak} and fetch_update
changelog: The invalid_atomic_ordering lint can now detect misuse of `compare_exchange`, `compare_exchange_weak`, and `fetch_update`.
---
I was surprised not to find an issue or existing support here, since these are the functions which are always hardest to get the ordering right on for me (as the allowed orderings for `fail` depend on the `success` parameter).
I believe this lint now covers all atomic methods which care about their ordering now, but I could be wrong.
Hopefully I didn't forget to do anything for the PR!
{print,write}-with-newline: do not suggest empty format string
changelog: do not suggest empty format strings in `print-with-newline` and `write-with-newline`
clarify margin of error in wording of float comparison operator lint messages
fixes#6040
changelog: change wording of float comparison operator to make margin of error less ambiguous
Add map_err_ignore lint
In a large code base a lot of times errors are ignored by using something like:
```rust
foo.map_err(|_| Some::Enum)?;
```
This drops the original error in favor of a enum that will not have the original error's context. This lint helps catch throwing away the original error in favor of an enum without its context.
---
*Please keep the line below*
changelog: Added map_err_ignore lint
Add a new lint, `manual-strip`, that suggests using the `str::strip_prefix`
and `str::strip_suffix` methods introduced in Rust 1.45 when the same
functionality is performed 'manually'.
Closes#5734
Attach tokens to all AST types used in `Nonterminal`
We perform token capturing when we have outer attributes (for nonterminals that support attributes - e.g. `Stmt`), or when we parse a `Nonterminal` for a `macro_rules!` argument. The full list of `Nonterminals` affected by this PR is:
* `NtBlock`
* `NtStmt`
* `NtTy`
* `NtMeta`
* `NtPath`
* `NtVis`
* `NtLiteral`
Of these nonterminals, only `NtStmt` and `NtLiteral` (which is actually just an `Expr`), support outer attributes - the rest only ever have token capturing perform when they match a `macro_rules!` argument.
This makes progress towards solving https://github.com/rust-lang/rust/issues/43081 - we now collect tokens for everything that might need them. However, we still need to handle `#[cfg]`, inner attributes, and misc pretty-printing issues (e.g. #75734)
I've separated the changes into (mostly) independent commits, which could be split into individual PRs for each `Nonterminal` variant. The purpose of having them all in one PR is to do a single Crater run for all of them.
Most of the changes in this PR are trivial (adding `tokens: None` everywhere we construct the various AST structs). The significant changes are:
* `ast::Visibility` is changed from `type Visibility = Spanned<VisibilityKind>` to a `struct Visibility { kind, span, tokens }`.
* `maybe_collect_tokens` is made generic, and used for both `ast::Expr` and `ast::Stmt`.
* Some of the statement-parsing functions are refactored so that we can capture the trailing semicolon.
* `Nonterminal` and `Expr` both grew by 8 bytes, as some of the structs which are stored inline (rather than behind a `P`) now have an `Option<TokenStream>` field. Hopefully the performance impact of doing this is negligible.
Add lint panic in result
### Change
Adding a new "restriction" lint that will emit a warning when using "panic", "unimplemented" or "unreachable" in a function of type option/result.
### Motivation
Some codebases must avoid crashes at all costs, and hence functions of type option/result must return an error instead of crashing.
### Test plan
Running:
TESTNAME=panic_in_result cargo uitest ---
changelog: none
Improve the "known problems" section of `interior_mutable_key`
* Remove the mention to `Rc` and `Arc` as these are `Freeze` (despite my intuition) so the lint correctly handles already.
* Instead, explain what could cause a false positive, and mention `bytes` as an example.
---
changelog: Improved the "known problems" section of `interior_mutable_key`
improve the suggestion of the lint `unit-arg`
Fixes#5823Fixes#6015
Changes
```
help: move the expression in front of the call...
|
3 | g();
|
help: ...and use a unit literal instead
|
3 | o.map_or((), |i| f(i))
|
```
into
```
help: move the expression in front of the call and replace it with the unit literal `()`
|
3 | g();
| o.map_or((), |i| f(i))
|
```
changelog: improve the suggestion of the lint `unit-arg`
Add CONST_ITEM_MUTATION lint
Fixes#74053Fixes#55721
This PR adds a new lint `CONST_ITEM_MUTATION`.
Given an item `const FOO: SomeType = ..`, this lint fires on:
* Attempting to write directly to a field (`FOO.field = some_val`) or
array entry (`FOO.array_field[0] = val`)
* Taking a mutable reference to the `const` item (`&mut FOO`), including
through an autoderef `FOO.some_mut_self_method()`
The lint message explains that since each use of a constant creates a
new temporary, the original `const` item will not be modified.
* Remove the mention to `Rc` and `Arc` as these are `Freeze`
so the lint correctly handles already.
* Instead, explain what could cause a false positive,
and mention `bytes` as an example.
We no longer lint assignments to const item fields in the
`temporary_assignment` lint, since this is now covered by the
`CONST_ITEM_MUTATION` lint.
Additionally, we `#![allow(const_item_mutation)]` in the
`borrow_interior_mutable_const.rs` test. Clippy UI tests are run with
`-D warnings`, which seems to cause builtin lints to prevent Clippy
lints from running.
Support dataflow problems on arbitrary lattices
This PR implements last of the proposed extensions I mentioned in the design meeting for the original dataflow refactor. It extends the current dataflow framework to work with arbitrary lattices, not just `BitSet`s. This is a prerequisite for dataflow-enabled MIR const-propagation. Personally, I am skeptical of the usefulness of doing const-propagation pre-monomorphization, since many useful constants only become known after monomorphization (e.g. `size_of::<T>()`) and users have a natural tendency to hand-optimize the rest. It's probably worth exprimenting with, however, and others have shown interest cc `@rust-lang/wg-mir-opt.`
The `Idx` associated type is moved from `AnalysisDomain` to `GenKillAnalysis` and replaced with an associated `Domain` type that must implement `JoinSemiLattice`. Like before, each `Analysis` defines the "bottom value" for its domain, but can no longer override the dataflow join operator. Analyses that want to use set intersection must now use the `lattice::Dual` newtype. `GenKillAnalysis` impls have an additional requirement that `Self::Domain: BorrowMut<BitSet<Self::Idx>>`, which effectively means that they must use `BitSet<Self::Idx>` or `lattice::Dual<BitSet<Self::Idx>>` as their domain.
Most of these changes were mechanical. However, because a `Domain` is no longer always a powerset of some index type, we can no longer use an `IndexVec<BasicBlock, GenKillSet<A::Idx>>>` to store cached block transfer functions. Instead, we use a boxed `dyn Fn` trait object. I discuss a few alternatives to the current approach in a commit message.
The majority of new lines of code are to preserve existing Graphviz diagrams for those unlucky enough to have to debug dataflow analyses. I find these diagrams incredibly useful when things are going wrong and considered regressing them unacceptable, especially the pretty-printing of `MovePathIndex`s, which are used in many dataflow analyses. This required a parallel `fmt` trait used only for printing dataflow domains, as well as a refactoring of the `graphviz` module now that we cannot expect the domain to be a `BitSet`. Some features did have to be removed, such as the gen/kill display mode (which I didn't use but existed to mirror the output of the old dataflow framework) and line wrapping. Since I had to rewrite much of it anyway, I took the opportunity to switch to a `Visitor` for printing dataflow state diffs instead of using cursors, which are error prone for code that must be generic over both forward and backward analyses. As a side-effect of this change, we no longer have quadratic behavior when writing graphviz diagrams for backward dataflow analyses.
r? `@pnkfelix`
Fix FP in `same_item_push`
Don't emit a lint when the pushed item doesn't have Clone trait
Fix#5979
changelog: Fix FP in `same_item_push` not to emit a lint when the pushed item doesn't have Clone trait
useless_attribute: Permit wildcard_imports and enum_glob_use
Fixes#5918
changelog: `useless_attribute`: Permit `wildcard_imports` and `enum_glob_use` on `use` items
default_trait_access: Fix wrong suggestion
https://github.com/rust-lang/rust-clippy/issues/5975#issuecomment-683751131
> I think the underlying problem is clippy suggests code with complete parameters, not clippy triggers this lint even for complex types. AFAIK, If code compiles with `Default::default`, it doesn't need to specify any parameters, as type inference is working. (So, in this case, `default_trait_access` should suggest `RefCell::default`.)
Fixes#5975Fixes#5990
changelog: `default_trait_access`: fixed wrong suggestion
