| #![crate_type = "lib"] |
| |
| // An example from #57165 of the linked-list cursor-like pattern of #46859/#48001, where the |
| // polonius alpha analysis shows the same imprecision as NLLs, unlike the datalog implementation. |
| |
| //@ ignore-compare-mode-polonius (explicit revisions) |
| //@ revisions: nll polonius legacy |
| //@ [nll] known-bug: #57165 |
| //@ [polonius] known-bug: #57165 |
| //@ [polonius] compile-flags: -Z polonius=next |
| //@ [legacy] check-pass |
| //@ [legacy] compile-flags: -Z polonius=legacy |
| |
| struct X { |
| next: Option<Box<X>>, |
| } |
| |
| fn no_control_flow() { |
| let mut b = Some(Box::new(X { next: None })); |
| let mut p = &mut b; |
| while let Some(now) = p { |
| p = &mut now.next; |
| } |
| } |
| |
| // NLLs and polonius alpha fail here |
| fn conditional() { |
| let mut b = Some(Box::new(X { next: None })); |
| let mut p = &mut b; |
| while let Some(now) = p { |
| if true { |
| p = &mut now.next; |
| } |
| } |
| } |
| |
| fn conditional_with_indirection() { |
| let mut b = Some(Box::new(X { next: None })); |
| let mut p = &mut b; |
| while let Some(now) = p { |
| if true { |
| p = &mut p.as_mut().unwrap().next; |
| } |
| } |
| } |
