mirror of https://github.com/rust-lang/rust
99 lines
2.3 KiB
Rust
99 lines
2.3 KiB
Rust
//@ check-pass
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#![warn(dropping_copy_types)]
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use std::mem::drop;
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use std::vec::Vec;
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#[derive(Copy, Clone)]
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struct SomeStruct;
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struct AnotherStruct {
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x: u8,
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y: u8,
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z: Vec<u8>,
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}
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impl Clone for AnotherStruct {
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fn clone(&self) -> AnotherStruct {
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AnotherStruct {
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x: self.x,
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y: self.y,
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z: self.z.clone(),
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}
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}
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}
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fn main() {
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let s1 = SomeStruct {};
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let s2 = s1;
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let s3 = &s1;
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let mut s4 = s1;
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let ref s5 = s1;
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drop(s1); //~ WARN calls to `std::mem::drop`
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drop(s2); //~ WARN calls to `std::mem::drop`
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drop(s3); //~ WARN calls to `std::mem::drop`
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drop(s4); //~ WARN calls to `std::mem::drop`
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drop(s5); //~ WARN calls to `std::mem::drop`
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let a1 = AnotherStruct {
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x: 255,
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y: 0,
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z: vec![1, 2, 3],
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};
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let a2 = &a1;
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let mut a3 = a1.clone();
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let ref a4 = a1;
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let a5 = a1.clone();
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drop(a2); //~ WARN calls to `std::mem::drop`
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drop(a3);
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drop(a4); //~ WARN calls to `std::mem::drop`
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drop(a5);
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}
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#[allow(unused)]
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#[allow(clippy::unit_cmp)]
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fn issue9482(x: u8) {
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fn println_and<T>(t: T) -> T {
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println!("foo");
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t
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}
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match x {
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// Don't lint (copy type), we only care about side-effects
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0 => drop(println_and(12)),
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// Don't lint (no copy type), we only care about side-effects
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1 => drop(println_and(String::new())),
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2 => {
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// Lint, even if we only care about the side-effect, it's already in a block
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drop(println_and(13)); //~ WARN calls to `std::mem::drop`
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},
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// Lint, idiomatic use is only in body of `Arm`
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3 if drop(println_and(14)) == () => (), //~ WARN calls to `std::mem::drop`
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// Lint, not a fn/method call
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4 => drop(2),//~ WARN calls to `std::mem::drop`
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_ => (),
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}
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}
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fn issue112653() {
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fn foo() -> Result<u8, ()> {
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println!("doing foo");
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Ok(0) // result is not always useful, the side-effect matters
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}
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fn bar() {
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println!("doing bar");
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}
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fn stuff() -> Result<(), ()> {
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match 42 {
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0 => drop(foo()?), // drop is needed because we only care about side-effects
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1 => bar(),
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_ => (), // doing nothing (no side-effects needed here)
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}
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Ok(())
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}
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}
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