rust/src/test/ui/borrowck/borrow-immutable-upvar-mutation.rs
2018-12-25 21:08:33 -07:00

36 lines
921 B
Rust

#![feature(unboxed_closures)]
// Tests that we can't assign to or mutably borrow upvars from `Fn`
// closures (issue #17780)
fn set(x: &mut usize) { *x = 5; }
fn to_fn<A,F:Fn<A>>(f: F) -> F { f }
fn to_fn_mut<A,F:FnMut<A>>(f: F) -> F { f }
fn main() {
// By-ref captures
{
let mut x = 0;
let _f = to_fn(|| x = 42); //~ ERROR cannot assign
let mut y = 0;
let _g = to_fn(|| set(&mut y)); //~ ERROR cannot borrow
let mut z = 0;
let _h = to_fn_mut(|| { set(&mut z); to_fn(|| z = 42); }); //~ ERROR cannot assign
}
// By-value captures
{
let mut x = 0;
let _f = to_fn(move || x = 42); //~ ERROR cannot assign
let mut y = 0;
let _g = to_fn(move || set(&mut y)); //~ ERROR cannot borrow
let mut z = 0;
let _h = to_fn_mut(move || { set(&mut z); to_fn(move || z = 42); }); //~ ERROR cannot assign
}
}