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