Revert: or_fun_call should lint calls to `const fn`s with no args
The changes in #5889 and #5984 were done under the incorrect assumption that a `const fn` with no args was guaranteed to be evaluated at compile time. A `const fn` is only guaranteed to be evaluated at compile time if it's inside a const context (the initializer of a `const` or a `static`).
See this [zulip conversation](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/Common.20misconception.3A.20.60const.20fn.60.20and.20its.20effect.20on.20codegen/near/208059113) for more details on this common misconception.
Given that none of the linted methods by `or_fun_call` can be called in const contexts, the lint should make no exceptions.
changelog: [`or_fun_call`] lints again calls to `const fn` with no args
Fix a FP in `explicit_counter_loop`
Fixes#4677 and #6074
Fix a false positive in `explicit_counter_loop` where the loop counter is used after incremented, adjust the test so that counters are incremented at the end of the loop and add the test for this false positive.
---
changelog: Fix a false positive in `explicit_counter_loop` where the loop counter is used after incremented
Add `rc_buffer` lint for checking Rc<String> and friends
Fixes#2623
This is a bit different from the original PR attempting to implement this type of lint. Rather than linting against converting into the unwanted types, this PR lints against declaring the unwanted type in a struct or function definition.
I'm reasonably happy with what I have here, although I used the fully qualified type names for the Path and OsString suggestions, and I'm not sure if I should have just used the short versions instead, even if they might not have been declared via use.
Also, I don't know if "buffer type" is the best way to put it or not. Alternatively I could call it a "growable type" or "growable buffer type", but I was thinking of PathBuf when I started making the lint.
changelog: Add `rc_buffer` lint
Fix a false positive in `explicit_counter_loop` where the loop counter is used after incremented,
adjust the test so that counters are incremented at the end of the loop
and add the test for this false positive.
Stabilize some Result methods as const
Stabilize the following methods of Result as const:
- `is_ok`
- `is_err`
- `as_ref`
A test is also included, analogous to the test for `const_option`.
These methods are currently const under the unstable feature `const_result` (tracking issue: #67520).
I believe these methods to be eligible for stabilization because of the stabilization of #49146 (Allow if and match in constants) and the trivial implementations, see also: [PR#75463](https://github.com/rust-lang/rust/pull/75463) and [PR#76135](https://github.com/rust-lang/rust/pull/76135).
Note: these methods are the only methods currently under the `const_result` feature, thus this PR results in the removal of the feature.
Related: #76225
* stop linting associated types and generic type parameters
* start linting ones in trait impls
whose corresponding definitions in the traits are generic
* remove the `is_copy` check
as presumably the only purpose of it is to allow
generics with `Copy` bounds as `Freeze` is internal
and generics are no longer linted
* remove the term 'copy' from the tests
as being `Copy` no longer have meaning
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
Add a lint for an async block/closure that yields a type that is itself awaitable.
This catches bugs of the form
tokio::spawn(async move {
let f = some_async_thing();
f // Oh no I forgot to await f so that work will never complete.
});
See the two XXXkhuey comments and the unfixed `_l` structure for things that need more thought.
*Please keep the line below*
changelog: none
or_fn_call: ignore nullary associated const fns
The fix in #5889 was missing associated functions.
changelog: Ignore also `const fn` methods in [`or_fun_call`]
Fixes#5693
This catches bugs of the form
tokio::spawn(async move {
let f = some_async_thing();
f // Oh no I forgot to await f so that work will never complete.
});
Fix FP in `to_string_in_display`
Don't emit a lint when `.to_string()` on anything that is not `self`
Fix#5967
changelog: Fix FP in `to_string_in_display` when calling `.to_string()` on anything that is not `self`
Corrects the float_equality_without_abs lint
Fixes an issue in the `float_equality_without_abs` lint. The lint suggestion was configured in a way that it lints the whole error and not just the subtraction part. In the current configuration the lint would suggest to change the expression in a wrong way, e.g.
```rust
let _ = (a - b) < f32::EPSILON; // before
let _ = (a - b).abs(); // after
```
This was dicovered by @flip1995. (See discussion of PR #5952).
Also the suggestion is now formatted via `utils::sugg`.
changelog: none
Fix `let_and_return` bad suggestion
Add a cast to the suggestion when the return expression has adjustments.
These adjustments are lost when the suggestion is applied.
This is similar to the problem in issue #4437.
Closes#5729
changelog: Fix `let_and_return` bad suggestion
Fix fp in `borrow_interior_mutable_const`
fixes#5796
changelog: fix false positive in `borrow_interior_mutable_const` when referencing a field behind a pointer.
Fix incorrect suggestion when `clone_on_ref_ptr` is triggered in macros
In the lint `clone_on_ref_ptr`, if the `span` is in a macro, don't expand it for suggestion.
Fixes: #2076
changelog: none
r? @ebroto
Add a cast to the suggestion when the return expression has adjustments.
These adjustments are lost when the suggestion is applied.
This is similar to the problem in issue #4437.
Closes#5729
Don't lint if it has always inline attribute
Don't trigger the lint `trivially_copy_pass_by_ref` if it has `#[inline(always)]` attribute.
Note: I am not particularly familiar with `inline` impacts, so I implemented this the way that if only `#[inline]` attribute is here (without `always`), the lint will still trigger. Also, it will still trigger if it has `#[inline(never)]`.
Just tell me if it sounds too much conservative.
Fixes: #5876
changelog: none
Prelude imports are exempt from wildcard import warnings. Until now only
imports of the form
```
use ...::prelude::*;
```
were considered. This change makes it so that the segment `prelude` can
show up anywhere, for instance:
```
use ...::prelude::v1::*;
```
Fixes#5917
Fix false positive in `PRECEDENCE` lint
Extend the lint to handle chains of methods combined with unary negation.
Closes#5924
changelog: Fix false negative in `PRECEDENCE` lint
This extends PR #73293 to handle patterns (Pat). Unlike expressions,
patterns do not support custom attributes, so we only need to capture
tokens during macro_rules! argument parsing.
Warn about assignments where left-hand side place expression is the same
as right-hand side value expression. For example, warn about assignment in:
```rust
pub struct Event {
id: usize,
x: i32,
y: i32,
}
pub fn copy_position(a: &mut Event, b: &Event) {
a.x = b.x;
a.y = a.y;
}
```
Add unnecessary lazy evaluation lint
changelog: Add [`unnecessary_lazy_evaluations`] lint that checks for usages of `unwrap_or_else` and similar functions that can be simplified.
Closes#5715
should_impl_trait - ignore methods with lifetime params
Fixes: #5617
changelog: don't lint should_implement_trait when an `Iterator::next` case has explicit parameters
