rust-clippy/tests/ui/needless_pass_by_value.rs
2018-05-29 10:56:58 +02:00

135 lines
2.9 KiB
Rust

#![warn(needless_pass_by_value)]
#![allow(dead_code, single_match, if_let_redundant_pattern_matching, many_single_char_names, option_option)]
use std::borrow::Borrow;
use std::convert::AsRef;
// `v` should be warned
// `w`, `x` and `y` are allowed (moved or mutated)
fn foo<T: Default>(v: Vec<T>, w: Vec<T>, mut x: Vec<T>, y: Vec<T>) -> Vec<T> {
assert_eq!(v.len(), 42);
consume(w);
x.push(T::default());
y
}
fn consume<T>(_: T) {}
struct Wrapper(String);
fn bar(x: String, y: Wrapper) {
assert_eq!(x.len(), 42);
assert_eq!(y.0.len(), 42);
}
// V implements `Borrow<V>`, but should be warned correctly
fn test_borrow_trait<T: Borrow<str>, U: AsRef<str>, V>(t: T, u: U, v: V) {
println!("{}", t.borrow());
println!("{}", u.as_ref());
consume(&v);
}
// ok
fn test_fn<F: Fn(i32) -> i32>(f: F) {
f(1);
}
// x should be warned, but y is ok
fn test_match(x: Option<Option<String>>, y: Option<Option<String>>) {
match x {
Some(Some(_)) => 1, // not moved
_ => 0,
};
match y {
Some(Some(s)) => consume(s), // moved
_ => (),
};
}
// x and y should be warned, but z is ok
fn test_destructure(x: Wrapper, y: Wrapper, z: Wrapper) {
let Wrapper(s) = z; // moved
let Wrapper(ref t) = y; // not moved
let Wrapper(_) = y; // still not moved
assert_eq!(x.0.len(), s.len());
println!("{}", t);
}
trait Foo {}
// `S: Serialize` is allowed to be passed by value, since a caller can pass `&S` instead
trait Serialize {}
impl<'a, T> Serialize for &'a T where T: Serialize {}
impl Serialize for i32 {}
fn test_blanket_ref<T: Foo, S: Serialize>(_foo: T, _serializable: S) {}
fn issue_2114(s: String, t: String, u: Vec<i32>, v: Vec<i32>) {
s.capacity();
let _ = t.clone();
u.capacity();
let _ = v.clone();
}
struct S<T, U>(T, U);
impl<T: Serialize, U> S<T, U> {
fn foo(
self, // taking `self` by value is always allowed
s: String,
t: String,
) -> usize {
s.len() + t.capacity()
}
fn bar(
_t: T, // Ok, since `&T: Serialize` too
) {
}
fn baz(
&self,
_u: U,
_s: Self,
) {
}
}
trait FalsePositive {
fn visit_str(s: &str);
fn visit_string(s: String) {
Self::visit_str(&s);
}
}
// shouldn't warn on extern funcs
extern "C" fn ext(x: String) -> usize { x.len() }
// whitelist RangeArgument
fn range<T: ::std::ops::RangeBounds<usize>>(range: T) {
let _ = range.start_bound();
}
struct CopyWrapper(u32);
fn bar_copy(x: u32, y: CopyWrapper) {
assert_eq!(x, 42);
assert_eq!(y.0, 42);
}
// x and y should be warned, but z is ok
fn test_destructure_copy(x: CopyWrapper, y: CopyWrapper, z: CopyWrapper) {
let CopyWrapper(s) = z; // moved
let CopyWrapper(ref t) = y; // not moved
let CopyWrapper(_) = y; // still not moved
assert_eq!(x.0, s);
println!("{}", t);
}
fn main() {}