mirror of https://github.com/rust-lang/rust
57 lines
1.2 KiB
Rust
57 lines
1.2 KiB
Rust
#![feature(unboxed_closures, tuple_trait)]
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// Tests that we can't assign to or mutably borrow upvars from `Fn`
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// closures (issue #17780)
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fn set(x: &mut usize) {
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*x = 5;
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}
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fn to_fn<A: std::marker::Tuple, F: Fn<A>>(f: F) -> F {
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f
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}
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fn to_fn_mut<A: std::marker::Tuple, F: FnMut<A>>(f: F) -> F {
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f
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}
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fn main() {
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// By-ref captures
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{
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let mut x = 0;
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let _f = to_fn(|| x = 42); //~ ERROR cannot assign
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let mut y = 0;
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let _g = to_fn(|| set(&mut y)); //~ ERROR cannot borrow
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let mut z = 0;
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let _h = to_fn_mut(|| {
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set(&mut z);
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to_fn(|| z = 42); //~ ERROR cannot assign
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});
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}
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// By-value captures
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{
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let mut x = 0;
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let _f = to_fn(move || x = 42); //~ ERROR cannot assign
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let mut y = 0;
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let _g = to_fn(move || set(&mut y)); //~ ERROR cannot borrow
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let mut z = 0;
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let _h = to_fn_mut(move || {
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set(&mut z);
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to_fn(move || z = 42);
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//~^ ERROR cannot assign
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});
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}
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}
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fn foo() -> Box<dyn Fn() -> usize> {
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let mut x = 0;
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Box::new(move || {
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x += 1; //~ ERROR cannot assign
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x
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})
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}
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