Struct rustc_typeck::check::upvar::InferBorrowKind

struct InferBorrowKind<'a, 'tcx> {
    fcx: &'a FnCtxt<'a, 'tcx>,
    closure_def_id: DefId,
    closure_span: Span,
    capture_information: FxIndexMap<Place<'tcx>, CaptureInfo<'tcx>>,
    fake_reads: Vec<(Place<'tcx>, FakeReadCause, HirId)>,
}

Fields

fcx: &'a FnCtxt<'a, 'tcx>

closure_def_id: DefId

closure_span: Span

capture_information: FxIndexMap<Place<'tcx>, CaptureInfo<'tcx>>

For each Place that is captured by the closure, we track the minimal kind of access we need (ref, ref mut, move, etc) and the expression that resulted in such access.

Consider closure where s.str1 is captured via an ImmutableBorrow and s.str2 via a MutableBorrow

struct SomeStruct { str1: String, str2: String }

// Assume that the HirId for the variable definition is `V1`
let mut s = SomeStruct { str1: format!("s1"), str2: format!("s2") }

let fix_s = |new_s2| {
    // Assume that the HirId for the expression `s.str1` is `E1`
    println!("Updating SomeStruct with str1=", s.str1);
    // Assume that the HirId for the expression `*s.str2` is `E2`
    s.str2 = new_s2;
};

For closure fix_s, (at a high level) the map contains

Place { V1, [ProjectionKind::Field(Index=0, Variant=0)] } : CaptureKind { E1, ImmutableBorrow }
Place { V1, [ProjectionKind::Field(Index=1, Variant=0)] } : CaptureKind { E2, MutableBorrow }

fake_reads: Vec<(Place<'tcx>, FakeReadCause, HirId)>

Implementations

impl<'a, 'tcx> InferBorrowKind<'a, 'tcx>

fn adjust_upvar_borrow_kind_for_consume(
    &mut self,
    place_with_id: &PlaceWithHirId<'tcx>,
    diag_expr_id: HirId
)

fn adjust_upvar_borrow_kind_for_mut(
    &mut self,
    place_with_id: &PlaceWithHirId<'tcx>,
    diag_expr_id: HirId
)

Indicates that place_with_id is being directly mutated (e.g., assigned to). If the place is based on a by-ref upvar, this implies that the upvar must be borrowed using an &mut borrow.

fn adjust_upvar_borrow_kind_for_unique(
    &mut self,
    place_with_id: &PlaceWithHirId<'tcx>,
    diag_expr_id: HirId
)

fn adjust_upvar_deref(
    &mut self,
    place_with_id: &PlaceWithHirId<'tcx>,
    diag_expr_id: HirId,
    borrow_kind: BorrowKind
)

fn adjust_upvar_borrow_kind(
    &mut self,
    place_with_id: &PlaceWithHirId<'tcx>,
    diag_expr_id: HirId,
    kind: BorrowKind
)

We infer the borrow_kind with which to borrow upvars in a stack closure. The borrow_kind basically follows a lattice of imm < unique-imm < mut, moving from left to right as needed (but never right to left). Here the argument mutbl is the borrow_kind that is required by some particular use.

fn init_capture_info_for_place(
    &mut self,
    place_with_id: &PlaceWithHirId<'tcx>,
    diag_expr_id: HirId
)

Trait Implementations

impl<'a, 'tcx> Delegate<'tcx> for InferBorrowKind<'a, 'tcx>

fn fake_read(
    &mut self,
    place: Place<'tcx>,
    cause: FakeReadCause,
    diag_expr_id: HirId
)

The place should be a fake read because of specified cause.

fn consume(&mut self, place_with_id: &PlaceWithHirId<'tcx>, diag_expr_id: HirId)

The value found at place is moved, depending on mode. Where diag_expr_id is the id used for diagnostics for place.

fn borrow(
    &mut self,
    place_with_id: &PlaceWithHirId<'tcx>,
    diag_expr_id: HirId,
    bk: BorrowKind
)

The value found at place is being borrowed with kind bk. diag_expr_id is the id used for diagnostics (see consume for more details).

fn mutate(&mut self, assignee_place: &PlaceWithHirId<'tcx>, diag_expr_id: HirId)

The path at assignee_place is being assigned to. diag_expr_id is the id used for diagnostics (see consume for more details).

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size: 104 bytes