145 lines
3.5 KiB
Rust
145 lines
3.5 KiB
Rust
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![feature(generators, generator_trait)]
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use std::ops::{State, Generator};
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use std::cell::Cell;
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fn borrow_local_inline() {
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// Not OK to yield with a borrow of a temporary.
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//
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// (This error occurs because the region shows up in the type of
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// `b` and gets extended by region inference.)
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let mut b = move || {
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let a = &3;
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yield();
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println!("{}", a);
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}; //~ ERROR E0597
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b.resume();
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}
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fn borrow_local_inline_done() {
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// No error here -- `a` is not in scope at the point of `yield`.
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let mut b = move || {
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{
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let a = &3;
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}
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yield();
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};
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b.resume();
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}
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fn borrow_local() {
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// Not OK to yield with a borrow of a temporary.
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//
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// (This error occurs because the region shows up in the type of
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// `b` and gets extended by region inference.)
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let mut b = move || {
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let a = 3;
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{
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let b = &a;
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yield();
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println!("{}", b);
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}
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}; //~ ERROR E0597
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b.resume();
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}
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fn reborrow_shared_ref(x: &i32) {
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// This is OK -- we have a borrow live over the yield, but it's of
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// data that outlives the generator.
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let mut b = move || {
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let a = &*x;
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yield();
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println!("{}", a);
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};
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b.resume();
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}
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fn reborrow_mutable_ref(x: &mut i32) {
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// This is OK -- we have a borrow live over the yield, but it's of
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// data that outlives the generator.
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let mut b = move || {
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let a = &mut *x;
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yield();
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println!("{}", a);
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};
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b.resume();
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}
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fn reborrow_mutable_ref_2(x: &mut i32) {
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// ...but not OK to go on using `x`.
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let mut b = || {
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let a = &mut *x;
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yield();
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println!("{}", a);
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};
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println!("{}", x); //~ ERROR E0501
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b.resume();
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}
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fn yield_during_iter_owned_data(x: Vec<i32>) {
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// The generator owns `x`, so we error out when yielding with a
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// reference to it. This winds up becoming a rather confusing
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// regionck error -- in particular, we would freeze with the
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// reference in scope, and it doesn't live long enough.
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let _b = move || {
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for p in &x {
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yield();
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}
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}; //~ ERROR E0597
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}
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fn yield_during_iter_borrowed_slice(x: &[i32]) {
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let _b = move || {
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for p in x {
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yield();
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}
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};
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}
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fn yield_during_iter_borrowed_slice_2() {
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let mut x = vec![22_i32];
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let _b = || {
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for p in &x {
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yield();
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}
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};
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println!("{:?}", x);
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}
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fn yield_during_iter_borrowed_slice_3() {
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// OK to take a mutable ref to `x` and yield
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// up pointers from it:
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let mut x = vec![22_i32];
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let mut b = || {
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for p in &mut x {
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yield p;
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}
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};
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b.resume();
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}
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fn yield_during_iter_borrowed_slice_4() {
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// ...but not OK to do that while reading
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// from `x` too
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let mut x = vec![22_i32];
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let mut b = || {
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for p in &mut x {
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yield p;
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}
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};
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println!("{}", x[0]); //~ ERROR cannot borrow `x` as immutable
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b.resume();
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}
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fn main() { }
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