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#![feature(if_let_guard)]
// Here is arielb1's basic example from rust-lang/rust#27282
// that AST borrowck is flummoxed by:
fn should_reject_destructive_mutate_in_guard() {
match Some(&4) {
None => {},
ref mut foo if {
(|| { let bar = foo; bar.take() })();
//~^ ERROR cannot move out of `foo` in pattern guard [E0507]
false } => { },
Some(s) => std::process::exit(*s),
}
match Some(&4) {
None => {},
ref mut foo if let Some(()) = {
(|| { let bar = foo; bar.take() })();
//~^ ERROR cannot move out of `foo` in pattern guard [E0507]
None } => { },
Some(s) => std::process::exit(*s),
}
}
// Here below is a case that needs to keep working: we only use the
// binding via immutable-borrow in the guard, and we mutate in the arm
// body.
fn allow_mutate_in_arm_body() {
match Some(&4) {
None => {},
ref mut foo if foo.is_some() => { foo.take(); () }
Some(s) => std::process::exit(*s),
}
match Some(&4) {
None => {},
ref mut foo if let Some(_) = foo => { foo.take(); () }
Some(s) => std::process::exit(*s),
}
}
// Here below is a case that needs to keep working: we only use the
// binding via immutable-borrow in the guard, and we move into the arm
// body.
fn allow_move_into_arm_body() {
match Some(&4) {
None => {},
mut foo if foo.is_some() => { foo.unwrap(); () }
Some(s) => std::process::exit(*s),
}
match Some(&4) {
None => {},
mut foo if let Some(_) = foo => { foo.unwrap(); () }
Some(s) => std::process::exit(*s),
}
}
fn main() {
should_reject_destructive_mutate_in_guard();
allow_mutate_in_arm_body();
allow_move_into_arm_body();
}
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