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add manual_repeat_n lint

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lapla-cogito 2024-12-20 22:29:06 +09:00
parent 25d319d1b2
commit 544f71f48d
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15 changed files with 188 additions and 19 deletions
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1
CHANGELOG.md
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@ -5768,6 +5768,7 @@ Released 2018-09-13
[`manual_range_contains`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_range_contains
[`manual_range_patterns`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_range_patterns
[`manual_rem_euclid`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_rem_euclid
[`manual_repeat_n`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_repeat_n
[`manual_retain`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_retain
[`manual_rotate`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_rotate
[`manual_saturating_arithmetic`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_saturating_arithmetic

1
clippy_lints/src/declared_lints.rs
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@ -420,6 +420,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
crate::methods::MANUAL_IS_VARIANT_AND_INFO,
crate::methods::MANUAL_NEXT_BACK_INFO,
crate::methods::MANUAL_OK_OR_INFO,
crate::methods::MANUAL_REPEAT_N_INFO,
crate::methods::MANUAL_SATURATING_ARITHMETIC_INFO,
crate::methods::MANUAL_SPLIT_ONCE_INFO,
crate::methods::MANUAL_STR_REPEAT_INFO,

43
clippy_lints/src/methods/manual_repeat_n.rs Normal file
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@ -0,0 +1,43 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::msrvs::{self, Msrv};
use clippy_utils::source::{snippet, snippet_with_context};
use clippy_utils::{expr_use_ctxt, fn_def_id, is_trait_method, std_or_core};
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_span::sym;
use super::MANUAL_REPEAT_N;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx Expr<'tcx>,
repeat_expr: &Expr<'_>,
take_arg: &Expr<'_>,
msrv: &Msrv,
) {
if msrv.meets(msrvs::REPEAT_N)
&& !expr.span.from_expansion()
&& is_trait_method(cx, expr, sym::Iterator)
&& let ExprKind::Call(_, [repeat_arg]) = repeat_expr.kind
&& let Some(def_id) = fn_def_id(cx, repeat_expr)
&& cx.tcx.is_diagnostic_item(sym::iter_repeat, def_id)
&& !expr_use_ctxt(cx, expr).is_ty_unified
&& let Some(std_or_core) = std_or_core(cx)
{
let mut app = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
MANUAL_REPEAT_N,
expr.span,
"this `repeat().take()` can be written more concisely",
"consider using `repeat_n()` instead",
format!(
"{std_or_core}::iter::repeat_n({}, {})",
snippet_with_context(cx, repeat_arg.span, expr.span.ctxt(), "..", &mut app).0,
snippet(cx, take_arg.span, "..")
),
app,
);
}
}

26
clippy_lints/src/methods/mod.rs
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@ -58,6 +58,7 @@ mod manual_inspect;
mod manual_is_variant_and;
mod manual_next_back;
mod manual_ok_or;
mod manual_repeat_n;
mod manual_saturating_arithmetic;
mod manual_str_repeat;
mod manual_try_fold;
@ -4339,6 +4340,29 @@ declare_clippy_lint! {
"using `NonZero::new_unchecked()` in a `const` context"
}
declare_clippy_lint! {
/// ### What it does
///
/// Checks for `repeat().take()` that can be replaced with `repeat_n()`.
///
/// ### Why is this bad?
///
/// Using `repeat_n()` is more concise and clearer. Also, `repeat_n()` is sometimes faster than `repeat().take()` when the type of the element is non-trivial to clone because the original value can be reused for the last `.next()` call rather than always cloning.
///
/// ### Example
/// ```no_run
/// let _ = std::iter::repeat(10).take(3);
/// ```
/// Use instead:
/// ```no_run
/// let _ = std::iter::repeat_n(10, 3);
/// ```
#[clippy::version = "1.86.0"]
pub MANUAL_REPEAT_N,
style,
"detect `repeat().take()` that can be replaced with `repeat_n()`"
}
pub struct Methods {
avoid_breaking_exported_api: bool,
msrv: Msrv,
@ -4506,6 +4530,7 @@ impl_lint_pass!(Methods => [
UNNECESSARY_MAP_OR,
DOUBLE_ENDED_ITERATOR_LAST,
USELESS_NONZERO_NEW_UNCHECKED,
MANUAL_REPEAT_N,
]);
/// Extracts a method call name, args, and `Span` of the method name.
@ -5176,6 +5201,7 @@ impl Methods {
("step_by", [arg]) => iterator_step_by_zero::check(cx, expr, arg),
("take", [arg]) => {
iter_out_of_bounds::check_take(cx, expr, recv, arg);
manual_repeat_n::check(cx, expr, recv, arg, &self.msrv);
if let Some(("cloned", recv2, [], _span2, _)) = method_call(recv) {
iter_overeager_cloned::check(
cx,

1
clippy_utils/src/lib.rs
View file

@ -15,6 +15,7 @@
clippy::missing_errors_doc,
clippy::missing_panics_doc,
clippy::must_use_candidate,
clippy::manual_repeat_n,
rustc::diagnostic_outside_of_impl,
rustc::untranslatable_diagnostic
)]

2
tests/ui/from_iter_instead_of_collect.fixed
View file

@ -1,6 +1,6 @@
#![warn(clippy::from_iter_instead_of_collect)]
#![allow(unused_imports)]
#![allow(clippy::useless_vec)]
#![allow(clippy::useless_vec, clippy::manual_repeat_n)]
use std::collections::{BTreeMap, BTreeSet, HashMap, VecDeque};

2
tests/ui/from_iter_instead_of_collect.rs
View file

@ -1,6 +1,6 @@
#![warn(clippy::from_iter_instead_of_collect)]
#![allow(unused_imports)]
#![allow(clippy::useless_vec)]
#![allow(clippy::useless_vec, clippy::manual_repeat_n)]
use std::collections::{BTreeMap, BTreeSet, HashMap, VecDeque};

30
tests/ui/manual_repeat_n.fixed Normal file
View file

@ -0,0 +1,30 @@
#![warn(clippy::manual_repeat_n)]
use std::iter::repeat;
fn main() {
let _ = std::iter::repeat_n(10, 3);
let _ = std::iter::repeat_n(String::from("foo"), 4);
for value in std::iter::repeat_n(5, 3) {}
let _: Vec<_> = std::iter::repeat_n(String::from("bar"), 10).collect();
let _ = std::iter::repeat_n(vec![1, 2], 2);
}
mod foo_lib {
pub fn iter() -> std::iter::Take<std::iter::Repeat<&'static [u8]>> {
todo!()
}
}
fn foo() {
let _ = match 1 {
1 => foo_lib::iter(),
// Shouldn't lint because `external_lib::iter` doesn't return `std::iter::RepeatN`.
2 => std::iter::repeat([1, 2].as_slice()).take(2),
_ => todo!(),
};
}

30
tests/ui/manual_repeat_n.rs Normal file
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@ -0,0 +1,30 @@
#![warn(clippy::manual_repeat_n)]
use std::iter::repeat;
fn main() {
let _ = repeat(10).take(3);
let _ = repeat(String::from("foo")).take(4);
for value in std::iter::repeat(5).take(3) {}
let _: Vec<_> = std::iter::repeat(String::from("bar")).take(10).collect();
let _ = repeat(vec![1, 2]).take(2);
}
mod foo_lib {
pub fn iter() -> std::iter::Take<std::iter::Repeat<&'static [u8]>> {
todo!()
}
}
fn foo() {
let _ = match 1 {
1 => foo_lib::iter(),
// Shouldn't lint because `external_lib::iter` doesn't return `std::iter::RepeatN`.
2 => std::iter::repeat([1, 2].as_slice()).take(2),
_ => todo!(),
};
}

35
tests/ui/manual_repeat_n.stderr Normal file
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@ -0,0 +1,35 @@
error: this `repeat().take()` can be written more concisely
--> tests/ui/manual_repeat_n.rs:6:13
|
LL | let _ = repeat(10).take(3);
| ^^^^^^^^^^^^^^^^^^ help: consider using `repeat_n()` instead: `std::iter::repeat_n(10, 3)`
|
= note: `-D clippy::manual-repeat-n` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::manual_repeat_n)]`
error: this `repeat().take()` can be written more concisely
--> tests/ui/manual_repeat_n.rs:8:13
|
LL | let _ = repeat(String::from("foo")).take(4);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `repeat_n()` instead: `std::iter::repeat_n(String::from("foo"), 4)`
error: this `repeat().take()` can be written more concisely
--> tests/ui/manual_repeat_n.rs:10:18
|
LL | for value in std::iter::repeat(5).take(3) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `repeat_n()` instead: `std::iter::repeat_n(5, 3)`
error: this `repeat().take()` can be written more concisely
--> tests/ui/manual_repeat_n.rs:12:21
|
LL | let _: Vec<_> = std::iter::repeat(String::from("bar")).take(10).collect();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `repeat_n()` instead: `std::iter::repeat_n(String::from("bar"), 10)`
error: this `repeat().take()` can be written more concisely
--> tests/ui/manual_repeat_n.rs:14:13
|
LL | let _ = repeat(vec![1, 2]).take(2);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `repeat_n()` instead: `std::iter::repeat_n(vec![1, 2], 2)`
error: aborting due to 5 previous errors

2
tests/ui/manual_str_repeat.fixed
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@ -1,4 +1,4 @@
#![allow(non_local_definitions)]
#![allow(non_local_definitions, clippy::manual_repeat_n)]
#![warn(clippy::manual_str_repeat)]
use std::borrow::Cow;

2
tests/ui/manual_str_repeat.rs
View file

@ -1,4 +1,4 @@
#![allow(non_local_definitions)]
#![allow(non_local_definitions, clippy::manual_repeat_n)]
#![warn(clippy::manual_str_repeat)]
use std::borrow::Cow;

3
tests/ui/slow_vector_initialization.fixed
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@ -1,4 +1,5 @@
#![allow(clippy::useless_vec)]
#![allow(clippy::useless_vec, clippy::manual_repeat_n)]
use std::iter::repeat;
fn main() {
resize_vector();

3
tests/ui/slow_vector_initialization.rs
View file

@ -1,4 +1,5 @@
#![allow(clippy::useless_vec)]
#![allow(clippy::useless_vec, clippy::manual_repeat_n)]
use std::iter::repeat;
fn main() {
resize_vector();

26
tests/ui/slow_vector_initialization.stderr
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@ -1,5 +1,5 @@
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:13:20
--> tests/ui/slow_vector_initialization.rs:14:20
|
LL | let mut vec1 = Vec::with_capacity(len);
| ____________________^
@ -11,7 +11,7 @@ LL | | vec1.extend(repeat(0).take(len));
= help: to override `-D warnings` add `#[allow(clippy::slow_vector_initialization)]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:19:20
--> tests/ui/slow_vector_initialization.rs:20:20
|
LL | let mut vec2 = Vec::with_capacity(len - 10);
| ____________________^
@ -20,7 +20,7 @@ LL | | vec2.extend(repeat(0).take(len - 10));
| |_________________________________________^ help: consider replacing this with: `vec![0; len - 10]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:27:20
--> tests/ui/slow_vector_initialization.rs:28:20
|
LL | let mut vec4 = Vec::with_capacity(len);
| ____________________^
@ -29,7 +29,7 @@ LL | | vec4.extend(repeat(0).take(vec4.capacity()));
| |________________________________________________^ help: consider replacing this with: `vec![0; len]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:38:27
--> tests/ui/slow_vector_initialization.rs:39:27
|
LL | let mut resized_vec = Vec::with_capacity(30);
| ___________________________^
@ -38,7 +38,7 @@ LL | | resized_vec.resize(30, 0);
| |_____________________________^ help: consider replacing this with: `vec![0; 30]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:42:26
--> tests/ui/slow_vector_initialization.rs:43:26
|
LL | let mut extend_vec = Vec::with_capacity(30);
| __________________________^
@ -47,7 +47,7 @@ LL | | extend_vec.extend(repeat(0).take(30));
| |_________________________________________^ help: consider replacing this with: `vec![0; 30]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:50:20
--> tests/ui/slow_vector_initialization.rs:51:20
|
LL | let mut vec1 = Vec::with_capacity(len);
| ____________________^
@ -56,7 +56,7 @@ LL | | vec1.resize(len, 0);
| |_______________________^ help: consider replacing this with: `vec![0; len]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:59:20
--> tests/ui/slow_vector_initialization.rs:60:20
|
LL | let mut vec3 = Vec::with_capacity(len - 10);
| ____________________^
@ -65,7 +65,7 @@ LL | | vec3.resize(len - 10, 0);
| |____________________________^ help: consider replacing this with: `vec![0; len - 10]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:63:20
--> tests/ui/slow_vector_initialization.rs:64:20
|
LL | let mut vec4 = Vec::with_capacity(len);
| ____________________^
@ -74,7 +74,7 @@ LL | | vec4.resize(vec4.capacity(), 0);
| |___________________________________^ help: consider replacing this with: `vec![0; len]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:68:12
--> tests/ui/slow_vector_initialization.rs:69:12
|
LL | vec1 = Vec::with_capacity(10);
| ____________^
@ -83,7 +83,7 @@ LL | | vec1.resize(10, 0);
| |______________________^ help: consider replacing this with: `vec![0; 10]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:76:20
--> tests/ui/slow_vector_initialization.rs:77:20
|
LL | let mut vec1 = Vec::new();
| ____________________^
@ -92,7 +92,7 @@ LL | | vec1.resize(len, 0);
| |_______________________^ help: consider replacing this with: `vec![0; len]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:81:20
--> tests/ui/slow_vector_initialization.rs:82:20
|
LL | let mut vec3 = Vec::new();
| ____________________^
@ -101,7 +101,7 @@ LL | | vec3.resize(len - 10, 0);
| |____________________________^ help: consider replacing this with: `vec![0; len - 10]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:86:12
--> tests/ui/slow_vector_initialization.rs:87:12
|
LL | vec1 = Vec::new();
| ____________^
@ -110,7 +110,7 @@ LL | | vec1.resize(10, 0);
| |______________________^ help: consider replacing this with: `vec![0; 10]`
error: slow zero-filling initialization
--> tests/ui/slow_vector_initialization.rs:90:12
--> tests/ui/slow_vector_initialization.rs:91:12
|
LL | vec1 = vec![];
| ____________^