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Add more cases to the useless_conversion lint (#13756)

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The new cases are the application of `Into::into` or `From::from`
through the following functions with no effect:
- `Option::map()`
- `Result::map()` and `Result::map_err()`
- `ControlFlow::map_break()` and `ControlFlow::map_err()`
- `Iterator::map()`

changelog: [`useless_conversion`]: detect useless calls to `Into::into`
and `From::from` application through `map*` methods
This commit is contained in:
Alejandra González 2024-12-02 15:41:25 +00:00 • committed by GitHub
commit 2ddfc92ea2
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GPG key ID: B5690EEEBB952194
5 changed files with 240 additions and 42 deletions
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45
tests/ui/useless_conversion.fixed
View file

@ -3,6 +3,8 @@
// FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
#![allow(static_mut_refs)]
use std::ops::ControlFlow;
fn test_generic<T: Copy>(val: T) -> T {
let _ = val;
val
@ -297,3 +299,46 @@ impl From<Foo<'a'>> for Foo<'b'> {
Foo
}
}
fn direct_application() {
let _: Result<(), std::io::Error> = test_issue_3913();
//~^ useless_conversion
let _: Result<(), std::io::Error> = test_issue_3913();
//~^ useless_conversion
let _: Result<(), std::io::Error> = test_issue_3913();
//~^ useless_conversion
let _: Result<(), std::io::Error> = test_issue_3913();
//~^ useless_conversion
let c: ControlFlow<()> = ControlFlow::Continue(());
let _: ControlFlow<()> = c;
//~^ useless_conversion
let c: ControlFlow<()> = ControlFlow::Continue(());
let _: ControlFlow<()> = c;
//~^ useless_conversion
struct Absorb;
impl From<()> for Absorb {
fn from(_: ()) -> Self {
Self
}
}
impl From<std::io::Error> for Absorb {
fn from(_: std::io::Error) -> Self {
Self
}
}
let _: Vec<u32> = [1u32].into_iter().collect();
//~^ useless_conversion
// No lint for those
let _: Result<Absorb, std::io::Error> = test_issue_3913().map(Into::into);
let _: Result<(), Absorb> = test_issue_3913().map_err(Into::into);
let _: Result<Absorb, std::io::Error> = test_issue_3913().map(From::from);
let _: Result<(), Absorb> = test_issue_3913().map_err(From::from);
}
fn gen_identity<T>(x: [T; 3]) -> Vec<T> {
x.into_iter().collect()
//~^ useless_conversion
}

45
tests/ui/useless_conversion.rs
View file

@ -3,6 +3,8 @@
// FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
#![allow(static_mut_refs)]
use std::ops::ControlFlow;
fn test_generic<T: Copy>(val: T) -> T {
let _ = T::from(val);
val.into()
@ -297,3 +299,46 @@ impl From<Foo<'a'>> for Foo<'b'> {
Foo
}
}
fn direct_application() {
let _: Result<(), std::io::Error> = test_issue_3913().map(Into::into);
//~^ useless_conversion
let _: Result<(), std::io::Error> = test_issue_3913().map_err(Into::into);
//~^ useless_conversion
let _: Result<(), std::io::Error> = test_issue_3913().map(From::from);
//~^ useless_conversion
let _: Result<(), std::io::Error> = test_issue_3913().map_err(From::from);
//~^ useless_conversion
let c: ControlFlow<()> = ControlFlow::Continue(());
let _: ControlFlow<()> = c.map_break(Into::into);
//~^ useless_conversion
let c: ControlFlow<()> = ControlFlow::Continue(());
let _: ControlFlow<()> = c.map_continue(Into::into);
//~^ useless_conversion
struct Absorb;
impl From<()> for Absorb {
fn from(_: ()) -> Self {
Self
}
}
impl From<std::io::Error> for Absorb {
fn from(_: std::io::Error) -> Self {
Self
}
}
let _: Vec<u32> = [1u32].into_iter().map(Into::into).collect();
//~^ useless_conversion
// No lint for those
let _: Result<Absorb, std::io::Error> = test_issue_3913().map(Into::into);
let _: Result<(), Absorb> = test_issue_3913().map_err(Into::into);
let _: Result<Absorb, std::io::Error> = test_issue_3913().map(From::from);
let _: Result<(), Absorb> = test_issue_3913().map_err(From::from);
}
fn gen_identity<T>(x: [T; 3]) -> Vec<T> {
x.into_iter().map(Into::into).collect()
//~^ useless_conversion
}

124
tests/ui/useless_conversion.stderr
View file

@ -1,5 +1,5 @@
error: useless conversion to the same type: `T`
--> tests/ui/useless_conversion.rs:7:13
--> tests/ui/useless_conversion.rs:9:13
|
LL | let _ = T::from(val);
| ^^^^^^^^^^^^ help: consider removing `T::from()`: `val`
@ -11,220 +11,268 @@ LL | #![deny(clippy::useless_conversion)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: useless conversion to the same type: `T`
--> tests/ui/useless_conversion.rs:8:5
--> tests/ui/useless_conversion.rs:10:5
|
LL | val.into()
| ^^^^^^^^^^ help: consider removing `.into()`: `val`
error: useless conversion to the same type: `i32`
--> tests/ui/useless_conversion.rs:20:22
--> tests/ui/useless_conversion.rs:22:22
|
LL | let _: i32 = 0i32.into();
| ^^^^^^^^^^^ help: consider removing `.into()`: `0i32`
error: useless conversion to the same type: `std::str::Lines<'_>`
--> tests/ui/useless_conversion.rs:50:22
--> tests/ui/useless_conversion.rs:52:22
|
LL | if Some("ok") == lines.into_iter().next() {}
| ^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `lines`
error: useless conversion to the same type: `std::str::Lines<'_>`
--> tests/ui/useless_conversion.rs:55:21
--> tests/ui/useless_conversion.rs:57:21
|
LL | let mut lines = text.lines().into_iter();
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `text.lines()`
error: useless conversion to the same type: `std::str::Lines<'_>`
--> tests/ui/useless_conversion.rs:61:22
--> tests/ui/useless_conversion.rs:63:22
|
LL | if Some("ok") == text.lines().into_iter().next() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `text.lines()`
error: useless conversion to the same type: `std::ops::Range<i32>`
--> tests/ui/useless_conversion.rs:67:13
--> tests/ui/useless_conversion.rs:69:13
|
LL | let _ = NUMBERS.into_iter().next();
| ^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `NUMBERS`
error: useless conversion to the same type: `std::ops::Range<i32>`
--> tests/ui/useless_conversion.rs:72:17
--> tests/ui/useless_conversion.rs:74:17
|
LL | let mut n = NUMBERS.into_iter();
| ^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `NUMBERS`
error: useless conversion to the same type: `std::string::String`
--> tests/ui/useless_conversion.rs:134:21
--> tests/ui/useless_conversion.rs:136:21
|
LL | let _: String = "foo".to_string().into();
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into()`: `"foo".to_string()`
error: useless conversion to the same type: `std::string::String`
--> tests/ui/useless_conversion.rs:135:21
--> tests/ui/useless_conversion.rs:137:21
|
LL | let _: String = From::from("foo".to_string());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `From::from()`: `"foo".to_string()`
error: useless conversion to the same type: `std::string::String`
--> tests/ui/useless_conversion.rs:136:13
--> tests/ui/useless_conversion.rs:138:13
|
LL | let _ = String::from("foo".to_string());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `String::from()`: `"foo".to_string()`
error: useless conversion to the same type: `std::string::String`
--> tests/ui/useless_conversion.rs:137:13
--> tests/ui/useless_conversion.rs:139:13
|
LL | let _ = String::from(format!("A: {:04}", 123));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `String::from()`: `format!("A: {:04}", 123)`
error: useless conversion to the same type: `std::str::Lines<'_>`
--> tests/ui/useless_conversion.rs:138:13
--> tests/ui/useless_conversion.rs:140:13
|
LL | let _ = "".lines().into_iter();
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `"".lines()`
error: useless conversion to the same type: `std::vec::IntoIter<i32>`
--> tests/ui/useless_conversion.rs:139:13
--> tests/ui/useless_conversion.rs:141:13
|
LL | let _ = vec![1, 2, 3].into_iter().into_iter();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `vec![1, 2, 3].into_iter()`
error: useless conversion to the same type: `std::string::String`
--> tests/ui/useless_conversion.rs:140:21
--> tests/ui/useless_conversion.rs:142:21
|
LL | let _: String = format!("Hello {}", "world").into();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into()`: `format!("Hello {}", "world")`
error: useless conversion to the same type: `i32`
--> tests/ui/useless_conversion.rs:145:13
--> tests/ui/useless_conversion.rs:147:13
|
LL | let _ = i32::from(a + b) * 3;
| ^^^^^^^^^^^^^^^^ help: consider removing `i32::from()`: `(a + b)`
error: useless conversion to the same type: `Foo<'a'>`
--> tests/ui/useless_conversion.rs:151:23
--> tests/ui/useless_conversion.rs:153:23
|
LL | let _: Foo<'a'> = s2.into();
| ^^^^^^^^^ help: consider removing `.into()`: `s2`
error: useless conversion to the same type: `Foo<'a'>`
--> tests/ui/useless_conversion.rs:153:13
--> tests/ui/useless_conversion.rs:155:13
|
LL | let _ = Foo::<'a'>::from(s3);
| ^^^^^^^^^^^^^^^^^^^^ help: consider removing `Foo::<'a'>::from()`: `s3`
error: useless conversion to the same type: `std::vec::IntoIter<Foo<'a'>>`
--> tests/ui/useless_conversion.rs:155:13
--> tests/ui/useless_conversion.rs:157:13
|
LL | let _ = vec![s4, s4, s4].into_iter().into_iter();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing `.into_iter()`: `vec![s4, s4, s4].into_iter()`
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:187:7
--> tests/ui/useless_conversion.rs:189:7
|
LL | b(vec![1, 2].into_iter());
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`: `vec![1, 2]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:177:13
--> tests/ui/useless_conversion.rs:179:13
|
LL | fn b<T: IntoIterator<Item = i32>>(_: T) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:188:7
--> tests/ui/useless_conversion.rs:190:7
|
LL | c(vec![1, 2].into_iter());
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`: `vec![1, 2]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:178:18
--> tests/ui/useless_conversion.rs:180:18
|
LL | fn c(_: impl IntoIterator<Item = i32>) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:189:7
--> tests/ui/useless_conversion.rs:191:7
|
LL | d(vec![1, 2].into_iter());
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`: `vec![1, 2]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:181:12
--> tests/ui/useless_conversion.rs:183:12
|
LL | T: IntoIterator<Item = i32>,
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:192:7
--> tests/ui/useless_conversion.rs:194:7
|
LL | b(vec![1, 2].into_iter().into_iter());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`s: `vec![1, 2]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:177:13
--> tests/ui/useless_conversion.rs:179:13
|
LL | fn b<T: IntoIterator<Item = i32>>(_: T) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:193:7
--> tests/ui/useless_conversion.rs:195:7
|
LL | b(vec![1, 2].into_iter().into_iter().into_iter());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`s: `vec![1, 2]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:177:13
--> tests/ui/useless_conversion.rs:179:13
|
LL | fn b<T: IntoIterator<Item = i32>>(_: T) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:239:24
--> tests/ui/useless_conversion.rs:241:24
|
LL | foo2::<i32, _>([1, 2, 3].into_iter());
| ^^^^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`: `[1, 2, 3]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:218:12
--> tests/ui/useless_conversion.rs:220:12
|
LL | I: IntoIterator<Item = i32> + Helper<X>,
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:247:14
--> tests/ui/useless_conversion.rs:249:14
|
LL | foo3([1, 2, 3].into_iter());
| ^^^^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`: `[1, 2, 3]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:227:12
--> tests/ui/useless_conversion.rs:229:12
|
LL | I: IntoIterator<Item = i32>,
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:256:16
--> tests/ui/useless_conversion.rs:258:16
|
LL | S1.foo([1, 2].into_iter());
| ^^^^^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`: `[1, 2]`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:253:27
--> tests/ui/useless_conversion.rs:255:27
|
LL | pub fn foo<I: IntoIterator>(&self, _: I) {}
| ^^^^^^^^^^^^
error: explicit call to `.into_iter()` in function argument accepting `IntoIterator`
--> tests/ui/useless_conversion.rs:275:44
--> tests/ui/useless_conversion.rs:277:44
|
LL | v0.into_iter().interleave_shortest(v1.into_iter());
| ^^^^^^^^^^^^^^ help: consider removing the `.into_iter()`: `v1`
|
note: this parameter accepts any `IntoIterator`, so you don't need to call `.into_iter()`
--> tests/ui/useless_conversion.rs:262:20
--> tests/ui/useless_conversion.rs:264:20
|
LL | J: IntoIterator,
| ^^^^^^^^^^^^
error: aborting due to 28 previous errors
error: useless conversion to the same type: `()`
--> tests/ui/useless_conversion.rs:304:58
|
LL | let _: Result<(), std::io::Error> = test_issue_3913().map(Into::into);
| ^^^^^^^^^^^^^^^^ help: consider removing
error: useless conversion to the same type: `std::io::Error`
--> tests/ui/useless_conversion.rs:306:58
|
LL | let _: Result<(), std::io::Error> = test_issue_3913().map_err(Into::into);
| ^^^^^^^^^^^^^^^^^^^^ help: consider removing
error: useless conversion to the same type: `()`
--> tests/ui/useless_conversion.rs:308:58
|
LL | let _: Result<(), std::io::Error> = test_issue_3913().map(From::from);
| ^^^^^^^^^^^^^^^^ help: consider removing
error: useless conversion to the same type: `std::io::Error`
--> tests/ui/useless_conversion.rs:310:58
|
LL | let _: Result<(), std::io::Error> = test_issue_3913().map_err(From::from);
| ^^^^^^^^^^^^^^^^^^^^ help: consider removing
error: useless conversion to the same type: `()`
--> tests/ui/useless_conversion.rs:314:31
|
LL | let _: ControlFlow<()> = c.map_break(Into::into);
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider removing
error: useless conversion to the same type: `()`
--> tests/ui/useless_conversion.rs:317:31
|
LL | let _: ControlFlow<()> = c.map_continue(Into::into);
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider removing
error: useless conversion to the same type: `u32`
--> tests/ui/useless_conversion.rs:331:41
|
LL | let _: Vec<u32> = [1u32].into_iter().map(Into::into).collect();
| ^^^^^^^^^^^^^^^^ help: consider removing
error: useless conversion to the same type: `T`
--> tests/ui/useless_conversion.rs:342:18
|
LL | x.into_iter().map(Into::into).collect()
| ^^^^^^^^^^^^^^^^ help: consider removing
error: aborting due to 36 previous errors