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rust-clippy/tests/ui/useless_conversion.rs

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// run-rustfix
#![deny(clippy::useless_conversion)]
#![allow(clippy::unnecessary_wraps)]
fn test_generic<T: Copy>(val: T) -> T {
let _ = T::from(val);
val.into()
}
fn test_generic2<T: Copy + Into<i32> + Into<U>, U: From<T>>(val: T) {
// ok
let _: i32 = val.into();
let _: U = val.into();
let _ = U::from(val);
}
fn test_questionmark() -> Result<(), ()> {
{
let _: i32 = 0i32.into();
Ok(Ok(()))
}??;
Ok(())
}
fn test_issue_3913() -> Result<(), std::io::Error> {
use std::fs;
use std::path::Path;
let path = Path::new(".");
for _ in fs::read_dir(path)? {}
Ok(())
}
fn test_issue_5833() -> Result<(), ()> {
let text = "foo\r\nbar\n\nbaz\n";
let lines = text.lines();
if Some("ok") == lines.into_iter().next() {}
Ok(())
}
fn main() {
test_generic(10i32);
test_generic2::<i32, i32>(10i32);
test_questionmark().unwrap();
test_issue_3913().unwrap();
test_issue_5833().unwrap();
let _: String = "foo".into();
let _: String = From::from("foo");
let _ = String::from("foo");
#[allow(clippy::useless_conversion)]
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{
let _: String = "foo".into();
let _ = String::from("foo");
let _ = "".lines().into_iter();
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}
let _: String = "foo".to_string().into();
let _: String = From::from("foo".to_string());
let _ = String::from("foo".to_string());
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let _ = String::from(format!("A: {:04}", 123));
let _ = "".lines().into_iter();
let _ = vec![1, 2, 3].into_iter().into_iter();
let _: String = format!("Hello {}", "world").into();
// keep parentheses around `a + b` for suggestion (see #4750)
let a: i32 = 1;
let b: i32 = 1;
let _ = i32::from(a + b) * 3;
// see #7205
let s: Foo<'a'> = Foo;
let _: Foo<'b'> = s.into();
let s2: Foo<'a'> = Foo;
let _: Foo<'a'> = s2.into();
let s3: Foo<'a'> = Foo;
let _ = Foo::<'a'>::from(s3);
let s4: Foo<'a'> = Foo;
let _ = vec![s4, s4, s4].into_iter().into_iter();
}
#[derive(Copy, Clone)]
struct Foo<const C: char>;
impl From<Foo<'a'>> for Foo<'b'> {
fn from(_s: Foo<'a'>) -> Self {
Foo
}
}