| //@ revisions: nll_target |
| |
| // The nll_beyond revision is disabled due to missing support from two-phase beyond autorefs |
| //@ unused-revision-names: nll_beyond |
| //@[nll_beyond]compile-flags: -Z two-phase-beyond-autoref |
| //@[nll_beyond]should-fail |
| |
| // This is a corner case that the current implementation is (probably) |
| // treating more conservatively than is necessary. But it also does |
| // not seem like a terribly important use case to cover. |
| // |
| // So this test is just making a note of the current behavior, with |
| // the caveat that in the future, the rules may be loosened, at which |
| // point this test might be thrown out. |
| // |
| // The convention for the listed revisions: "lxl" means lexical |
| // lifetimes (which can be easier to reason about). "nll" means |
| // non-lexical lifetimes. "nll_target" means the initial conservative |
| // two-phase borrows that only applies to autoref-introduced borrows. |
| // "nll_beyond" means the generalization of two-phase borrows to all |
| // `&mut`-borrows (doing so makes it easier to write code for specific |
| // corner cases). |
| |
| fn main() { |
| let mut vec = vec![0, 1]; |
| let delay: &mut Vec<_>; |
| { |
| let shared = &vec; |
| |
| // we reserve here, which could (on its own) be compatible |
| // with the shared borrow. But in the current implementation, |
| // its an error. |
| delay = &mut vec; |
| //[nll_beyond]~^ ERROR cannot borrow `vec` as mutable because it is also borrowed as immutable |
| //[nll_target]~^^ ERROR cannot borrow `vec` as mutable because it is also borrowed as immutable |
| |
| shared[0]; |
| } |
| |
| // the &mut-borrow only becomes active way down here. |
| // |
| // (At least in theory; part of the reason this test fails is that |
| // the constructed MIR throws in extra &mut reborrows which |
| // flummoxes our attempt to delay the activation point here.) |
| delay.push(2); |
| } |
