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// Test that we cannot mutate an outer variable that is not declared
// as `mut` through a closure. Also test that we CAN mutate a moved copy,
// unless this is a `Fn` closure. Issue #16749.
#![feature(unboxed_closures, tuple_trait)]
use std::mem;
fn to_fn<A:std::marker::Tuple,F:Fn<A>>(f: F) -> F { f }
fn to_fn_mut<A:std::marker::Tuple,F:FnMut<A>>(f: F) -> F { f }
fn a() {
let n = 0;
let mut f = to_fn_mut(|| {
n += 1; //~ ERROR cannot assign to `n`, as it is not declared as mutable
});
}
fn b() {
let mut n = 0;
let mut f = to_fn_mut(|| {
n += 1; // OK
});
}
fn c() {
let n = 0;
let mut f = to_fn_mut(move || {
// If we just did a straight-forward desugaring, this would
// compile, but we do something a bit more subtle, and hence
// we get an error.
n += 1; //~ ERROR cannot assign
});
}
fn d() {
let mut n = 0;
let mut f = to_fn_mut(move || {
n += 1; // OK
});
}
fn e() {
let n = 0;
let mut f = to_fn(move || {
n += 1; //~ ERROR cannot assign
});
}
fn f() {
let mut n = 0;
let mut f = to_fn(move || {
n += 1; //~ ERROR cannot assign
});
}
fn main() { }
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