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Positive coverage: loan_not_required_by_live_place_prefix / no prefix

no prefix
LineCoverageSource
1382✗(if let None = live_place.prefix())
──────── ("no prefix")
138412(loan_not_required_by_live_place_prefix(_env, _assumptions, _outlives, _loan, live_place) => ())

12 tests exercised this rule:

Source location: src/test_util.rs:516 (all coverage from this test)

#[test]
fn rustc_expectation_is_independent_of_borrowck_modes() {
    let before = rustc_runs();
    FormalityTest::new(NLL_ONLY_ERROR)
        .rustc_err(expect_test::expect![[r#"
            error[E0499]: cannot borrow `*m` as mutable more than once at a time
             --> lib.rs
              |
            3 | pub fn foo<'a00>(mut m: &'a00 mut Map) -> &'a00 mut Map {
              |            ---- lifetime `'a00` defined here
            4 |     {
            5 |         let mut n: &'_ mut Map = &mut *m;
              |                                  ------- first mutable borrow occurs here
            6 |         if false {
            7 |             return n;
              |                    - returning this value requires that `*m` is borrowed for `'a00`
            8 |         } else {
            9 |             let mut o: &'_ mut Map = &mut *m;
              |                                      ^^^^^^^ second mutable borrow occurs here

            For more information about this error, try `rustc --explain E0499`.
            error: could not compile `Foo` (lib) due to 1 previous error
        "#]])
        .borrowck_err(BorrowCheckFailure::Nll, expect_test::expect![[r#"
            the rule "borrow of disjoint places" at (nll.rs) failed because
              condition evaluated to false: `place_disjoint_from_place(&loan.place, &access.place)`
                &loan.place = *(m : &!lt_1 mut Map) : <&!lt_1 mut Map as Derefable>::Target
                &access.place = *(m : &!lt_1 mut Map) : <&!lt_1 mut Map as Derefable>::Target

            the rule "loan_cannot_outlive" at (nll.rs) failed because
              condition evaluated to false: `!outlived_by_loan.contains(&lifetime.upcast())`
                outlived_by_loan = {!lt_1, ?lt_2, ?lt_3}
                &lifetime.upcast() = !lt_1

            the rule "loan_not_required_by_universal_regions" at (nll.rs) failed because
              condition evaluated to false: `outlived_by_loan.iter().all(|p| match p
              {
                  Parameter::Ty(_) => false, Parameter::Lt(lt) => match lt.as_ref()
                  {
                      Lt::Static => false, Lt::Variable(Variable::UniversalVar(_)) => false,
                      Lt::Variable(Variable::ExistentialVar(_)) => true,
                      Lt::Variable(Variable::BoundVar(_)) =>
                      panic!("cannot outlive a bound var"), Lt::Erased => true,
                  }, Parameter::Const(_) => panic!("cannot outlive a constant"),
              })`

            the rule "write-indirect" at (nll.rs) failed because
              pattern `TypedPlaceExpressionData::Deref(place_loaned_ref)` did not match value `m`

            the rule "write-indirect" at (nll.rs) failed because
              condition evaluated to false: `place_accessed.is_prefix_of(place_loaned_ref)`
                place_accessed = *(m : &!lt_1 mut Map) : <&!lt_1 mut Map as Derefable>::Target
                place_loaned_ref = m : &!lt_1 mut Map"#]]);
    assert_eq!(rustc_runs() - before, 1);
}
Proof tree
… (200 of 3742 nodes shown)

Source location: tests/borrowck.rs:2470 (all coverage from this test)

fn min_problem_case_3<'a>(m: &'a mut Map) -> &'a mut Map {
    exists<'r0, 'r1> {
        let n: &'r0 mut Map = &'r0 mut *m;
        if true {
            return n;
        } else {
            let o: &'r1 mut Map = &'r1 mut *m;
            return o;
        }
    }
}
Proof tree
… (200 of 3742 nodes shown)

Source location: tests/borrowck.rs:2575 (all coverage from this test)

fn foo() -> i32 {
    exists<'r0, 'r1> {
        let result: i32;
        {
            let v1: i32 = 22_i32;
            let v2: &'r0 i32 = &'r1 v1;
            result = *v2;
        }
        return result;
    }
}
Proof tree
… (200 of 3630 nodes shown)

Source location: tests/borrowck.rs:2690 (all coverage from this test)

fn min_problem_case_3<'a>(m: &'a mut Map) -> &'a mut Map {
    exists<'r0, 'r1> {
        let n: &'r0 mut Map = &'r0 mut *m;
        if true {
        } else {
        }
        let o: &'r1 mut Map = &'r1 mut *m;
        return o;
    }
}
Proof tree
… (200 of 3713 nodes shown)

Source location: tests/borrowck.rs:2963 (all coverage from this test)

fn foo () -> u32 {
    exists<'l_p, 'l_q, 'loan_0, 'loan_1, 'loan_2, 'loan_3> {
        let a: u32 = 0_u32;
        let b: u32 = 0_u32;
        // In Rustc, the 1-tuple is needed for some reason
        // Niko does not 100% understand, else rustc is able to
        // see that this program is safe.
        let q: &'l_q mut u32 = &'loan_0 mut a;
        let p: &'l_p mut u32 = &'loan_1 mut a;
        if true {
            p = &'loan_1 mut a;
            q = &'loan_2 mut b;
        } else {
            p = &'loan_3 mut b;
        }
        *q = 1_u32;
        return *p;
    }
}
Proof tree
… (200 of 3956 nodes shown)

Source location: tests/borrowck.rs:3288 (all coverage from this test)

fn foo<'a>(m: &'a mut Map) -> &'a mut Map {
    exists<'r0, 'r1> {
        let n: &'r0 mut Map = &'r0 mut *m;
        if false {
            return n;
        } else {
            let o: &'r1 mut Map = &'r1 mut *m;
            return o;
        }
    }
}
Proof tree
… (200 of 3742 nodes shown)

Source location: tests/borrowck.rs:3715 (all coverage from this test)

fn reborrow<'a>(a: &'a mut u8) -> &'a mut u8 {
    exists<'r0, 'r1, 'r2, 'r3> {
        // This creates an outlives constraint
        let b: &'r1 mut u8 = &'r0 mut *a;
        if true {
            return b;
        } else {
            // this means the loan remains live
        }

        // If the outlives constraint propagated here,
        // we would get an error.
        let c: &'r3 mut u8 = &'r2 mut *a;
        return c;
    }
}
Proof tree
… (200 of 3741 nodes shown)

Source location: tests/borrowck.rs:4167 (all coverage from this test)

fn remove_last_node_recursive<'a>(node: &'a mut List) -> u32 {
    exists<'r0> {
        let next: &'r0 mut List = next_of::<'r0>(&'r0 mut *node);
        if true {
            remove_last_node_recursive::<'r0>(next);
        } else {
            *node = List { value: 0_u32 };
        }
        return 0_u32;
    }
}
Proof tree
… (200 of 3837 nodes shown)

Source location: tests/borrowck.rs:4415 (all coverage from this test)

fn conditional_with_indirection() -> u32 {
    exists<'r0, 'r1, 'r2, 'r3> {
        let b: X = X { value: 0_u32 };
        let p: &'r0 mut X = &'r1 mut b;
        'l: loop {
            let now: &'r2 mut X = &'r2 mut *p;
            if true {
                if true {
                    let next: &'r3 mut X = next_of::<'r3>(&'r3 mut *p);
                    p = next;
                } else {
                }
            } else {
                break 'l;
            }
        }
        return 0_u32;
    }
}
Proof tree
… (200 of 4849 nodes shown)

Source location: tests/borrowck.rs:4592 (all coverage from this test)

fn next<'a>(d: &'a mut Decoder) -> &'a u32 {
    exists<'r0, 'r1> {
        'l: loop {
            let buf: &'r0 u32 = fill_buf::<'r0>(&'r0 mut (*d).buf_read);
            let s: &'r1 u32 = decode::<'r1>(buf);
            if true {
                return s;
            } else {
            }
        }
    }
}
Proof tree
… (200 of 3994 nodes shown)

Source location: tests/borrowck.rs:4715 (all coverage from this test)

fn next<'s>(f: &'s mut Filter) -> &'s mut u32 {
    exists<'r0, 'r1, 'r2> {
        'l: loop {
            let item: &'r0 mut u32 = iter_next::<'r0>(&'r0 mut (*f).iter);
            if true {
                let keep: bool = call_predicate::<'r1, 'r2>(&'r1 mut (*f).predicate, &'r2 *item);
                if keep {
                    return item;
                } else {
                }
            } else {
                break 'l;
            }
        }
        return no_item::<'s>();
    }
}

Proof trees omitted for the remaining 2 tests; each one is on its test’s page in Coverage by test.

Source location: tests/codegen.rs:964 (all coverage from this test)

fn main() -> () {
    let x: u32 = 1_u32;
    exists<'a> {
        let r: &'a mut u32 = &'a mut x;
        x += update::<'a>(r);
    }
    println!(x);
}

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