Add `assigning_clones` lint
This PR is a "revival" of https://github.com/rust-lang/rust-clippy/pull/10613 (with `@kpreid's` permission).
I tried to resolve most of the unresolved things from the mentioned PR:
1) The lint now checks properly if we indeed call the functions `std::clone::Clone::clone` or `std::borrow::ToOwned::to_owned`.
2) It now supports both method and function (UFCS) calls.
3) A heuristic has been added to decide if the lint should apply. It will only apply if the type on which the method is called has a custom implementation of `clone_from/clone_into`. Notably, it will not trigger for types that use `#[derive(Clone)]`.
4) `Deref` handling has been (hopefully) a bit improved, but I'm not sure if it's ideal yet.
I also added a bunch of additional tests.
There are a few things that could be improved, but shouldn't be blockers:
1) When the right-hand side is a function call, it is transformed into e.g. `::std::clone::Clone::clone(...)`. It would be nice to either auto-import the `Clone` trait or use the original path and modify it (e.g. `clone::Clone::clone` -> `clone::Clone::clone_from`). I don't know how to modify the `QPath` to do that though.
2) The lint currently does not trigger when the left-hand side is a local variable without an initializer. This is overly conservative, since it could trigger when the variable has no initializer, but it has been already initialized at the moment of the function call, e.g.
```rust
let mut a;
...
a = Foo;
...
a = b.clone(); // Here the lint should trigger, but currently doesn't
```
These cases probably won't be super common, but it would be nice to make the lint more precise. I'm not sure how to do that though, I'd need access to some dataflow analytics or something like that.
changelog: new lint [`assigning_clones`]
[`misrefactored_assign_op`]: Fix duplicate diagnostics
Relate to #12379
The following diagnostics appear twice
```
--> tests/ui/assign_ops2.rs:26:5
|
LL | a *= a * a;
| ^^^^^^^^^^
|
help: did you mean `a = a * a` or `a = a * a * a`? Consider replacing it with
```
because `a` (lhs) appears in both left operand and right operand in the right hand side.
This PR fixes the issue so that if a diagnostic is created for an operand, the check of the other operand will be skipped. It's fine because the result is always the same in the affected operators.
changelog: [`misrefactored_assign_op`]: Fix duplicate diagnostics
Don't emit "missing backticks" lint if the element is wrapped in `<code>` HTML tags
Fixes#9473.
changelog: Don't emit "missing backticks" lint if the element is wrapped in `<code>` HTML tags
Existing names for values of this type are `sess`, `parse_sess`,
`parse_session`, and `ps`. `sess` is particularly annoying because
that's also used for `Session` values, which are often co-located, and
it can be difficult to know which type a value named `sess` refers to.
(That annoyance is the main motivation for this change.) `psess` is nice
and short, which is good for a name used this much.
The commit also renames some `parse_sess_created` values as
`psess_created`.
Add missing header for `manual_is_variant_and`
Noticed this while generating our lint completions failed in rust-analyzer (separate PR from https://github.com/rust-lang/rust-clippy/pull/12415 as I made these via the github interface quickly)
changelog: none
[`identity_op`]: Fix duplicate diagnostics
Relates to #12379
In the `identity_op` lint, the following diagnostic was emitted two times
```
--> tests/ui/identity_op.rs:156:5
|
LL | 1 * 1;
| ^^^^^ help: consider reducing it to: `1`
|
```
because both of the left operand and the right operand are the identity element of the multiplication.
This PR fixes the issue so that if a diagnostic is created for an operand, the check of the other operand will be skipped. It's fine because the result is always the same in the affected operators.
---
changelog: [`identity_op`]: Fix duplicate diagnostics
Check for try blocks in `question_mark` more consistently
Fixes#12337
I split this PR up into two commits since this moves a method out of an `impl`, which makes for a pretty bad diff (the `&self` parameter is now unused, and there isn't a reason for that function to be part of the `impl` now).
The first commit is the actual relevant change and the 2nd commit just moves stuff (github's "hide whitespace" makes the diff easier to look at)
------------
Now for the actual issue:
`?` within `try {}` blocks desugars to a `break` to the block, rather than a `return`, so that changes behavior in those cases.
The lint has multiple patterns to look for and in *some* of them it already does correctly check whether we're in a try block, but this isn't done for all of its patterns.
We could add another `self.inside_try_block()` check to the function that looks for `let-else-return`, but I chose to actually just move those checks out and instead have them in `LintPass::check_{stmt,expr}`. This has the advantage that we can't (easily) accidentally forget to add that check in new patterns that might be added in the future.
(There's also a bit of a subtle interaction between two lints, where `question_mark`'s LintPass calls into `manual_let_else`, so I added a check to make sure we don't avoid linting for something that doesn't have anything to do with `?`)
changelog: [`question_mark`]: avoid linting on try blocks in more cases
fix [`derive_partial_eq_without_eq`] FP on trait projection
fixes: #9413#9319
---
changelog: fix [`derive_partial_eq_without_eq`] FP on trait projection
Well, this is awkward, it works but I don't understand why, why `clippy_utils::ty::implements_trait` couldn't detects the existance of `Eq` trait, even thought it's obviously present in the derive attribute.
Pointers cannot be converted to integers at compile time
Fix#12402
changelog: [`transmutes_expressible_as_ptr_casts`]: do not suggest invalid const casts
Dedup std_instead_of_core by using first segment span for uniqueness
Relates to #12379.
Instead of checking that the paths have an identical span, it checks that the relevant `std` part of the path segment's span is identical. Added a multiline test, because my first implementation was worse and failed that, then I realized that you could grab the span off the first_segment `Ident`.
I did find another bug that isn't addressed by this, and that exists on master as well.
The path:
```Rust
use std::{io::Write, fmt::Display};
```
Will get fixed into:
```Rust
use core::{io::Write, fmt::Display};
```
Which doesn't compile since `io::Write` isn't in `core`, if any of those paths are present in `core` it'll do the replace and cause a miscompilation. Do you think I should file a separate bug for that? Since `rustfmt` default splits those up it isn't that big of a deal.
Rustfmt:
```Rust
// Pre
use std::{io::Write, fmt::Display};
// Post
use std::fmt::Display;
use std::io::Write;
```
---
changelog: [`std_instead_of_core`]: Fix duplicated output on multiple imports
fix: `manual_memcpy` wrong indexing for multi dimensional arrays
fixes: #9334
This PR fixes an invalid suggestion for multi-dimensional arrays.
For example,
```rust
let src = vec![vec![0; 5]; 5];
let mut dst = vec![0; 5];
for i in 0..5 {
dst[i] = src[i][i];
}
```
For the above code, Clippy suggests `dst.copy_from_slice(&src[i]);`, but it is not compilable because `i` is only used to loop the array.
I adjusted it so that Clippy `manual_memcpy` works properly for multi-dimensional arrays.
changelog: [`manual_memcpy`]: Fixes invalid indexing suggestions for multi-dimensional arrays
Add stubs in IR and ABI for `f16` and `f128`
This is the very first step toward the changes in https://github.com/rust-lang/rust/pull/114607 and the [`f16` and `f128` RFC](https://rust-lang.github.io/rfcs/3453-f16-and-f128.html). It adds the types to `rustc_type_ir::FloatTy` and `rustc_abi::Primitive`, and just propagates those out as `unimplemented!` stubs where necessary.
These types do not parse yet so there is no feature gate, and it should be okay to use `unimplemented!`.
The next steps will probably be AST support with parsing and the feature gate.
r? `@compiler-errors`
cc `@Nilstrieb` suggested breaking the PR up in https://github.com/rust-lang/rust/pull/120645#issuecomment-1925900572
`os_local` impl of `thread_local` — regardless of whether it is const and
unlike other implementations — includes an `fn __init(): EXPR`.
Existing implementation of the lint checked for the presence of said
function and whether the expr can be made const. Because for `os_local`
we always have an `__init()`, it triggers for const implementations.
The solution is to check whether the `__init()` function is already const.
If it is `const`, there is nothing to do. Otherwise, we verify that we can
make it const.
Co-authored-by: Alejandra González <blyxyas@gmail.com>
Add new `mixed_attributes_style` lint
Add a new lint to detect cases where both inner and outer attributes are used on a same item.
r? `@llogiq`
----
changelog: Add new [`mixed_attributes_style`] lint
The following code used to trigger the lint:
```rs
macro_rules! make_closure {
() => {
(|| {})
};
}
make_closure!()();
```
The lint would suggest to replace `make_closure!()()` with
`make_closure!()`, which changes the code and removes the call to the
closure from the macro. This commit fixes that.
Fixes#12358
Fix `nonminimal_bool` lint regression
Fixes#12371.
Fixes#12369.
cc `@RalfJung`
The problem was an invalid condition. Shame on me...
changelog: Fix `nonminimal_bool` lint regression
[`map_entry`]: Check insert expression for map use
The lint makes sure that the map is not used (borrowed) before the call to `insert`. Since the lint creates a mutable borrow on the map with the `Entry`, it wouldn't be possible to replace such code with `Entry`. However, expressions up to the `insert` call are checked, but not expressions for the arguments of the `insert` call itself. This commit fixes that.
Fixes#11935
----
changelog: [`map_entry`]: Fix false positive when borrowing the map in the `insert` call
If the whole cast expression is a unary expression (`(*x as T)`) or an
addressof expression (`(&x as T)`), then not surrounding the suggestion
into a block risks us changing the precedence of operators if the cast
expression is followed by an operation with higher precedence than the
unary operator (`(*x as T).foo()` would become `*x.foo()`, which changes
what the `*` applies on).
The same is true if the expression encompassing the cast expression is a
unary expression or an addressof expression.
The lint supports the latter case, but missed the former one. This PR
fixes that.
Fixes#11968
The lint makes sure that the map is not used (borrowed) before the call
to `insert`. Since the lint creates a mutable borrow on the map with the
`Entry`, it wouldn't be possible to replace such code with `Entry`.
However, expressions up to the `insert` call are checked, but not
expressions for the arguments of the `insert` call itself. This commit
fixes that.
Fixes#11935
Fix sign-handling bugs and false negatives in `cast_sign_loss`
**Note: anyone should feel free to move this PR forward, I might not see notifications from reviewers.**
changelog: [`cast_sign_loss`]: Fix sign-handling bugs and false negatives
This PR fixes some arithmetic bugs and false negatives in PR #11883 (and maybe earlier PRs).
Cc `@J-ZhengLi`
I haven't updated the tests yet. I was hoping for some initial feedback before adding tests to cover the cases listed below.
Here are the issues I've attempted to fix:
#### `abs()` can return a negative value in release builds
Example:
```rust
i32::MIN.abs()
```
https://play.rust-lang.org/?version=stable&mode=release&edition=2021&gist=022d200f9ef6ee72f629c0c9c1af11b8
Docs: https://doc.rust-lang.org/std/primitive.i32.html#method.abs
Other overflows that produce negative values could cause false negatives (and underflows could produce false positives), but they're harder to detect.
#### Values with uncertain signs can be positive or negative
Any number of values with uncertain signs cause the whole expression to have an uncertain sign, because an uncertain sign can be positive or negative.
Example (from UI tests):
```rust
fn main() {
foo(a: i32, b: i32, c: i32) -> u32 {
(a * b * c * c) as u32
//~^ ERROR: casting `i32` to `u32` may lose the sign of the value
}
println!("{}", foo(1, -1, 1));
}
```
https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=165d2e2676ee8343b1b9fe60db32aadd
#### Handle `expect()` the same way as `unwrap()`
Since we're ignoring `unwrap()` we might as well do the same with `expect()`.
This doesn't seem to have tests but I'm happy to add some like `Some(existing_test).unwrap() as u32`.
#### A negative base to an odd exponent is guaranteed to be negative
An integer `pow()`'s sign is only uncertain when its operants are uncertain. (Ignoring overflow.)
Example:
```rust
((-2_i32).pow(3) * -2) as u32
```
This offsets some of the false positives created by one or more uncertain signs producing an uncertain sign. (Rather than just an odd number of uncertain signs.)
#### Both sides of a multiply or divide should be peeled recursively
I'm not sure why the lhs was peeled recursively, and the rhs was left intact. But the sign of any sequence of multiplies and divides is determined by the signs of its operands. (Ignoring overflow.)
I'm not sure what to use as an example here, because most expressions I want to use are const-evaluable.
But if `p()` is [a non-const function that returns a positive value](https://doc.rust-lang.org/std/primitive.i32.html#method.isqrt), and if the lint handles unary negation, these should all lint:
```rust
fn peel_all(x: i32) {
(-p(x) * -p(x) * -p(x)) as u32;
((-p(x) * -p(x)) * -p(x)) as u32;
(-p(x) * (-p(x) * -p(x))) as u32;
}
```
#### The right hand side of a Rem doesn't change the sign
Unlike Mul and Div,
> Given remainder = dividend % divisor, the remainder will have the same sign as the dividend.
https://doc.rust-lang.org/reference/expressions/operator-expr.html#arithmetic-and-logical-binary-operators
I'm not sure what to use as an example here, because most expressions I want to use are const-evaluable.
But if `p()` is [a non-const function that returns a positive value](https://doc.rust-lang.org/std/primitive.i32.html#method.isqrt), and if the lint handles unary negation, only the first six expressions should lint.
The expressions that start with a constant should lint (or not lint) regardless of whether the lint supports `p()` or unary negation, because only the dividend's sign matters.
Example:
```rust
fn rem_lhs(x: i32) {
(-p(x) % -1) as u32;
(-p(x) % 1) as u32;
(-1 % -p(x)) as u32;
(-1 % p(x)) as u32;
(-1 % -x) as u32;
(-1 % x) as u32;
// These shouldn't lint:
(p(x) % -1) as u32;
(p(x) % 1) as u32;
(1 % -p(x)) as u32;
(1 % p(x)) as u32;
(1 % -x) as u32;
(1 % x) as u32;
}
```
#### There's no need to bail on other expressions
When peeling, any other operators or expressions can be left intact and sent to the constant evaluator.
If these expressions can be evaluated, this offsets some of the false positives created by one or more uncertain signs producing an uncertain sign. If not, they end up marked as having uncertain sign.
[`read_line_without_trim`]: detect string literal comparison and `.ends_with()` calls
This lint now also realizes that a comparison like `s == "foo"` and calls such as `s.ends_with("foo")` will fail if `s` was initialized by a call to `Stdin::read_line` (because of the trailing newline).
changelog: [`read_line_without_trim`]: detect string literal comparison and `.ends_with()` calls
r? `@giraffate` assigning you because you reviewed #10970 that added this lint, so this is kinda a followup PR ^^
fix suggestion error in [`useless_vec`]
fixes: #12101
---
changelog: fix suggestion error in [`useless_vec`]
r+ `@matthiaskrgr` since they opened the issue?
Empty docs
Fixes https://github.com/rust-lang/rust-clippy/issues/9931
changelog: [`empty_doc`]: Detects documentation that is empty.
changelog: Doc comment lints now trigger for struct field and enum variant documentation
When encountering code such as:
```
Box::new(outer::Inner::default())
```
clippy would suggest replacing with `Box::<Inner>::default()`, dropping
the `outer::` segment. This behavior is incorrect and that commit fixes
it.
What it does is it checks the contents of the `Box::new` and, if it is
of the form `A::B::default`, does a text replacement, inserting `A::B`
in the `Box`'s quickfix generic list.
If the source does not match that pattern (including `Vec::from(..)`
or other `T::new()` calls), we then fallback to the original code.
Fixes#11927
Look for `implied_bounds_in_impls` in more positions
With this, we lint `impl Trait` implied bounds in more positions:
- Type alias impl trait
- Associated type position impl trait
- Argument position impl trait
- these are not opaque types, but instead are desugared to `where` clauses, so we need extra logic for finding them (`check_generics`), however the rest of the logic is the same
Before this, we'd only lint RPIT `impl Trait`s.
"Hide whitespaces" and reviewing commits individually might make this easier
changelog: [`implied_bounds_in_impls`]: start linting implied bounds in APIT, ATPIT, TAIT
Merge `single_call_fn` post-crate visitor into lint pass
The `single_call_fn` lint worked by first collecting a list of function definitions in the lint pass, then populating the list of uses for each function in a second visitor after the crate is checked.
Doing another pass through the crate shouldn't be needed, and we should be able to do it in the same lint pass, by looking for path references to functions only and then processing them post-crate.
Other changes:
- `FxHashMap` -> `FxIndexMap` so that we emit warnings in a consistent order, as we see them (making the diff a bit confusing to look at, because warnings were moved around)
- no longer storing a `Vec<Span>` per function: an enum representing "seen once" or "seen more than once" should be enough (only the first element is used later)
- "used here" help is now a note
I also noticed that it lints on trait methods with a default implementation, but not on regular trait methods without a body (because that's what `check_fn` does). I'm not sure if that's useful though, maybe we shouldn't lint trait methods at all? It's not like you can avoid it sometimes (but then again it's a restriction lint). Either way, I left the behavior where it was before so that there are no functional changes made in this PR and it's purely a refactor. I can change it though
changelog: none
FIX(12243): redundant_guards
Fixed#12243
changelog: Fix[`redundant_guards`]
I have made a correction so that no warning does appear when y.is_empty() is used within a constant function as follows.
```rust
pub const fn const_fn(x: &str) {
match x {
// Shouldn't lint.
y if y.is_empty() => {},
_ => {},
}
}
```
Add new `unnecessary_get_then_check` lint
No issue linked to this as far as I can see. It's a lint I discovered that could be added when I worked on another lint.
r? `@llogiq`
changelog: Add new `unnecessary_get_then_check` lint
A warning is now suppressed when "<str_va> if <str_var>.is_empty" is used in a constant function.
FIX: instead of clippy_util::in_const
FIX: Merged `redundant_guards_const_fn.rs` into `redundant_guards.rs`.
