mirror of https://github.com/rust-lang/rust
145 lines
3.4 KiB
Rust
145 lines
3.4 KiB
Rust
//@ edition:2018
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//@ check-pass
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#![feature(coroutines, stmt_expr_attributes)]
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#![warn(unused)]
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#![allow(unreachable_code)]
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pub fn unintentional_copy_one() {
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let mut last = None;
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let mut f = move |s| {
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last = Some(s); //~ WARN value assigned to `last` is never read
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//~| WARN unused variable: `last`
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};
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f("a");
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f("b");
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f("c");
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dbg!(last.unwrap());
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}
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pub fn unintentional_copy_two() {
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let mut sum = 0;
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(1..10).for_each(move |x| {
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sum += x; //~ WARN unused variable: `sum`
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});
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dbg!(sum);
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}
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pub fn f() {
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let mut c = 0;
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// Captured by value, but variable is dead on entry.
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let _ = move || {
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c = 1; //~ WARN value captured by `c` is never read
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println!("{}", c);
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};
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let _ = async move {
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c = 1; //~ WARN value captured by `c` is never read
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println!("{}", c);
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};
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// Read and written to, but never actually used.
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let _ = move || {
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c += 1; //~ WARN unused variable: `c`
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};
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let _ = async move {
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c += 1; //~ WARN value assigned to `c` is never read
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//~| WARN unused variable: `c`
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};
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let _ = move || {
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println!("{}", c);
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// Value is read by closure itself on later invocations.
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c += 1;
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};
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let b = Box::new(42);
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let _ = move || {
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println!("{}", c);
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// Never read because this is FnOnce closure.
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c += 1; //~ WARN value assigned to `c` is never read
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drop(b);
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};
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let _ = async move {
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println!("{}", c);
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// Never read because this is a coroutine.
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c += 1; //~ WARN value assigned to `c` is never read
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};
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}
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pub fn nested() {
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let mut d = None;
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let mut e = None;
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let _ = || {
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let _ = || {
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d = Some("d1"); //~ WARN value assigned to `d` is never read
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d = Some("d2");
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};
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let _ = move || {
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e = Some("e1"); //~ WARN value assigned to `e` is never read
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//~| WARN unused variable: `e`
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e = Some("e2"); //~ WARN value assigned to `e` is never read
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};
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};
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}
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pub fn g<T: Default>(mut v: T) {
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let _ = |r| {
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if r {
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v = T::default(); //~ WARN value assigned to `v` is never read
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} else {
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drop(v);
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}
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};
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}
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pub fn h<T: Copy + Default + std::fmt::Debug>() {
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let mut z = T::default();
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let _ = move |b| {
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loop {
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if b {
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z = T::default(); //~ WARN value assigned to `z` is never read
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//~| WARN unused variable: `z`
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} else {
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return;
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}
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}
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dbg!(z);
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};
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}
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async fn yield_now() {
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todo!();
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}
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pub fn async_coroutine() {
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let mut state: u32 = 0;
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let _ = async {
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state = 1;
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yield_now().await;
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state = 2;
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yield_now().await;
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state = 3;
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};
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let _ = async move {
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state = 4; //~ WARN value assigned to `state` is never read
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//~| WARN unused variable: `state`
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yield_now().await;
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state = 5; //~ WARN value assigned to `state` is never read
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};
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}
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pub fn coroutine() {
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let mut s: u32 = 0;
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let _ = #[coroutine] |_| {
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s = 0;
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yield ();
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s = 1; //~ WARN value assigned to `s` is never read
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yield (s = 2);
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s = yield (); //~ WARN value assigned to `s` is never read
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s = 3;
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};
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}
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fn main() {}
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