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| 1 | +//! Test for #145328: ensure the lifetime of a `super let` binding within an `if let` scrutinee is |
| 2 | +//! at most the scope of the `if` condition. In particular, test `pin!` since it's implemented in |
| 3 | +//! terms of `super let`. |
| 4 | +//@ run-pass |
| 5 | +//@ revisions: e2021 e2024 |
| 6 | +//@ [e2021] edition: 2021 |
| 7 | +//@ [e2024] edition: 2024 |
| 8 | + |
| 9 | +#![feature(if_let_guard)] |
| 10 | +#![feature(super_let)] |
| 11 | +#![expect(irrefutable_let_patterns)] |
| 12 | + |
| 13 | +use std::cell::RefCell; |
| 14 | +use std::pin::pin; |
| 15 | + |
| 16 | +fn main() { |
| 17 | + // The `super let` bindings here should have the same scope as `if let` temporaries. |
| 18 | + // In Rust 2021, this means it lives past the end of the `if` expression. |
| 19 | + // In Rust 2024, this means it lives to the end of the `if`'s success block. |
| 20 | + assert_drop_order(0..=2, |o| { |
| 21 | + #[cfg(e2021)] |
| 22 | + ( |
| 23 | + if let _ = { super let _x = o.log(2); } { o.push(0) }, |
| 24 | + o.push(1), |
| 25 | + ); |
| 26 | + #[cfg(e2024)] |
| 27 | + ( |
| 28 | + if let _ = { super let _x = o.log(2); } { o.push(0) }, |
| 29 | + o.push(1), |
| 30 | + ); |
| 31 | + }); |
| 32 | + assert_drop_order(0..=2, |o| { |
| 33 | + #[cfg(e2021)] |
| 34 | + ( |
| 35 | + if let true = { super let _x = o.log(2); false } {} else { o.push(0) }, |
| 36 | + o.push(1), |
| 37 | + ); |
| 38 | + #[cfg(e2024)] |
| 39 | + ( |
| 40 | + if let true = { super let _x = o.log(2); false } {} else { o.push(0) }, |
| 41 | + o.push(1), |
| 42 | + ); |
| 43 | + }); |
| 44 | + |
| 45 | + // `pin!` should behave likewise. |
| 46 | + assert_drop_order(0..=2, |o| { |
| 47 | + #[cfg(e2021)] (if let _ = pin!(o.log(2)) { o.push(0) }, o.push(1)); |
| 48 | + #[cfg(e2024)] (if let _ = pin!(o.log(2)) { o.push(0) }, o.push(1)); |
| 49 | + }); |
| 50 | + assert_drop_order(0..=2, |o| { |
| 51 | + #[cfg(e2021)] |
| 52 | + ( |
| 53 | + if let None = Some(pin!(o.log(2))) {} else { o.push(0) }, |
| 54 | + o.push(1), |
| 55 | + ); |
| 56 | + #[cfg(e2024)] |
| 57 | + ( |
| 58 | + if let None = Some(pin!(o.log(2))) {} else { o.push(0) }, |
| 59 | + o.push(1), |
| 60 | + ); |
| 61 | + }); |
| 62 | + |
| 63 | + // `super let` bindings' scope should also be consistent with `if let` temporaries in guards. |
| 64 | + // Here, that means the `super let` binding in the second guard condition operand should be |
| 65 | + // dropped before the first operand's temporary. This is consistent across Editions. |
| 66 | + assert_drop_order(0..=1, |o| { |
| 67 | + match () { |
| 68 | + _ if let _ = o.log(0) |
| 69 | + && let _ = { super let _x = o.log(1); } => {} |
| 70 | + _ => unreachable!(), |
| 71 | + } |
| 72 | + }); |
| 73 | + assert_drop_order(0..=1, |o| { |
| 74 | + match () { |
| 75 | + _ if let _ = o.log(0) |
| 76 | + && let _ = pin!(o.log(1)) => {} |
| 77 | + _ => unreachable!(), |
| 78 | + } |
| 79 | + }); |
| 80 | +} |
| 81 | + |
| 82 | +// # Test scaffolding... |
| 83 | + |
| 84 | +struct DropOrder(RefCell<Vec<u64>>); |
| 85 | +struct LogDrop<'o>(&'o DropOrder, u64); |
| 86 | + |
| 87 | +impl DropOrder { |
| 88 | + fn log(&self, n: u64) -> LogDrop<'_> { |
| 89 | + LogDrop(self, n) |
| 90 | + } |
| 91 | + fn push(&self, n: u64) { |
| 92 | + self.0.borrow_mut().push(n); |
| 93 | + } |
| 94 | +} |
| 95 | + |
| 96 | +impl<'o> Drop for LogDrop<'o> { |
| 97 | + fn drop(&mut self) { |
| 98 | + self.0.push(self.1); |
| 99 | + } |
| 100 | +} |
| 101 | + |
| 102 | +#[track_caller] |
| 103 | +fn assert_drop_order( |
| 104 | + ex: impl IntoIterator<Item = u64>, |
| 105 | + f: impl Fn(&DropOrder), |
| 106 | +) { |
| 107 | + let order = DropOrder(RefCell::new(Vec::new())); |
| 108 | + f(&order); |
| 109 | + let order = order.0.into_inner(); |
| 110 | + let expected: Vec<u64> = ex.into_iter().collect(); |
| 111 | + assert_eq!(order, expected); |
| 112 | +} |
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