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This commit is contained in:
Sosthène Guédon 2022-07-19 22:08:03 +02:00
parent f3f86d8fd9
commit f30d7c2495
4 changed files with 59 additions and 53 deletions
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70
clippy_lints/src/methods/iter_once_empty.rs
View file

@ -1,5 +1,6 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::is_lang_ctor;
use clippy_utils::is_no_std_crate;
use clippy_utils::source::snippet;
use rustc_errors::Applicability;
@ -9,6 +10,22 @@ use rustc_lint::LateContext;
use super::{ITER_EMPTY, ITER_ONCE};
enum IterType {
Iter,
IterMut,
IntoIter,
}
impl IterType {
fn ref_prefix(&self) -> &'static str {
match self {
Self::Iter => "&",
Self::IterMut => "&mut ",
Self::IntoIter => "",
}
}
}
pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, method_name: &str, recv: &Expr<'_>) {
let item = match &recv.kind {
ExprKind::Array(v) if v.len() <= 1 => v.first(),
@ -32,39 +49,42 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, method_name:
},
_ => return,
};
let iter_type = match method_name {
"iter" => IterType::Iter,
"iter_mut" => IterType::IterMut,
"into_iter" => IterType::IntoIter,
_ => return,
};
if let Some(i) = item {
let (sugg, msg) = match method_name {
"iter" => (
format!("std::iter::once(&{})", snippet(cx, i.span, "...")),
"this `iter` call can be replaced with std::iter::once",
),
"iter_mut" => (
format!("std::iter::once(&mut {})", snippet(cx, i.span, "...")),
"this `iter_mut` call can be replaced with std::iter::once",
),
"into_iter" => (
format!("std::iter::once({})", snippet(cx, i.span, "...")),
"this `into_iter` call can be replaced with std::iter::once",
),
_ => return,
};
span_lint_and_sugg(cx, ITER_ONCE, expr.span, msg, "try", sugg, Applicability::Unspecified);
let sugg = format!(
"{}::iter::once({}{})",
if is_no_std_crate(cx) { "core" } else { "std" },
iter_type.ref_prefix(),
snippet(cx, i.span, "...")
);
span_lint_and_sugg(
cx,
ITER_ONCE,
expr.span,
&format!("`{method_name}` call on a collection with only one item"),
"try",
sugg,
Applicability::MaybeIncorrect,
);
} else {
let msg = match method_name {
"iter" => "this `iter call` can be replaced with std::iter::empty",
"iter_mut" => "this `iter_mut` call can be replaced with std::iter::empty",
"into_iter" => "this `into_iter` call can be replaced with std::iter::empty",
_ => return,
};
span_lint_and_sugg(
cx,
ITER_EMPTY,
expr.span,
msg,
&format!("`{method_name}` call on an empty collection"),
"try",
"std::iter::empty()".to_string(),
Applicability::Unspecified,
if is_no_std_crate(cx) {
"core::iter::empty()".to_string()
} else {
"std::iter::empty()".to_string()
},
Applicability::MaybeIncorrect,
);
}
}

18
clippy_lints/src/methods/mod.rs
View file

@ -2308,14 +2308,7 @@ declare_clippy_lint! {
declare_clippy_lint! {
/// ### What it does
///
/// Checks for usage of:
///
/// - `[foo].iter()`
/// - `[foo].iter_mut()`
/// - `[foo].into_iter()`
/// - `Some(foo).iter()`
/// - `Some(foo).iter_mut()`
/// - `Some(foo).into_iter()`
/// Checks for calls to `iter`, `iter_mut` or `into_iter` on collections containing a single item
///
/// ### Why is this bad?
///
@ -2346,14 +2339,7 @@ declare_clippy_lint! {
declare_clippy_lint! {
/// ### What it does
///
/// Checks for usage of:
///
/// - `[].iter()`
/// - `[].iter_mut()`
/// - `[].into_iter()`
/// - `None.iter()`
/// - `None.iter_mut()`
/// - `None.into_iter()`
/// Checks for calls to `iter`, `iter_mut` or `into_iter` on empty collections
///
/// ### Why is this bad?
///

12
tests/ui/iter_empty.stderr
View file

@ -1,4 +1,4 @@
error: this `into_iter` call can be replaced with std::iter::empty
error: `into_iter` call on an empty collection
--> $DIR/iter_empty.rs:6:16
|
LL | assert_eq!([].into_iter().next(), Option::<i32>::None);
@ -6,31 +6,31 @@ LL | assert_eq!([].into_iter().next(), Option::<i32>::None);
|
= note: `-D clippy::iter-empty` implied by `-D warnings`
error: this `iter_mut` call can be replaced with std::iter::empty
error: `iter_mut` call on an empty collection
--> $DIR/iter_empty.rs:7:16
|
LL | assert_eq!([].iter_mut().next(), Option::<&mut i32>::None);
| ^^^^^^^^^^^^^ help: try: `std::iter::empty()`
error: this `iter call` can be replaced with std::iter::empty
error: `iter` call on an empty collection
--> $DIR/iter_empty.rs:8:16
|
LL | assert_eq!([].iter().next(), Option::<&i32>::None);
| ^^^^^^^^^ help: try: `std::iter::empty()`
error: this `into_iter` call can be replaced with std::iter::empty
error: `into_iter` call on an empty collection
--> $DIR/iter_empty.rs:9:16
|
LL | assert_eq!(None.into_iter().next(), Option::<i32>::None);
| ^^^^^^^^^^^^^^^^ help: try: `std::iter::empty()`
error: this `iter_mut` call can be replaced with std::iter::empty
error: `iter_mut` call on an empty collection
--> $DIR/iter_empty.rs:10:16
|
LL | assert_eq!(None.iter_mut().next(), Option::<&mut i32>::None);
| ^^^^^^^^^^^^^^^ help: try: `std::iter::empty()`
error: this `iter call` can be replaced with std::iter::empty
error: `iter` call on an empty collection
--> $DIR/iter_empty.rs:11:16
|
LL | assert_eq!(None.iter().next(), Option::<&i32>::None);

12
tests/ui/iter_once.stderr
View file

@ -1,4 +1,4 @@
error: this `into_iter` call can be replaced with std::iter::once
error: `into_iter` call on a collection with only one item
--> $DIR/iter_once.rs:6:16
|
LL | assert_eq!([123].into_iter().next(), Some(123));
@ -6,31 +6,31 @@ LL | assert_eq!([123].into_iter().next(), Some(123));
|
= note: `-D clippy::iter-once` implied by `-D warnings`
error: this `iter_mut` call can be replaced with std::iter::once
error: `iter_mut` call on a collection with only one item
--> $DIR/iter_once.rs:7:16
|
LL | assert_eq!([123].iter_mut().next(), Some(&mut 123));
| ^^^^^^^^^^^^^^^^ help: try: `std::iter::once(&mut 123)`
error: this `iter` call can be replaced with std::iter::once
error: `iter` call on a collection with only one item
--> $DIR/iter_once.rs:8:16
|
LL | assert_eq!([123].iter().next(), Some(&123));
| ^^^^^^^^^^^^ help: try: `std::iter::once(&123)`
error: this `into_iter` call can be replaced with std::iter::once
error: `into_iter` call on a collection with only one item
--> $DIR/iter_once.rs:9:16
|
LL | assert_eq!(Some(123).into_iter().next(), Some(123));
| ^^^^^^^^^^^^^^^^^^^^^ help: try: `std::iter::once(123)`
error: this `iter_mut` call can be replaced with std::iter::once
error: `iter_mut` call on a collection with only one item
--> $DIR/iter_once.rs:10:16
|
LL | assert_eq!(Some(123).iter_mut().next(), Some(&mut 123));
| ^^^^^^^^^^^^^^^^^^^^ help: try: `std::iter::once(&mut 123)`
error: this `iter` call can be replaced with std::iter::once
error: `iter` call on a collection with only one item
--> $DIR/iter_once.rs:11:16
|
LL | assert_eq!(Some(123).iter().next(), Some(&123));