Enum rustc_mir_build::build::expr::as_place::PlaceBase

pub(crate) enum PlaceBase {
    Local(Local),
    Upvar {
        var_hir_id: HirId,
        closure_def_id: DefId,
        closure_kind: ClosureKind,
    },
}

The “outermost” place that holds this value.

Variants

Local(Local)

Denotes the start of a Place.

Upvar

When building place for an expression within a closure, the place might start off a captured path. When capture_disjoint_fields is enabled, we might not know the capture index (within the desugared closure) of the captured path until most of the projections are applied. We use PlaceBase::Upvar to keep track of the root variable off of which the captured path starts, the closure the capture belongs to and the trait the closure implements.

Once we have figured out the capture index, we can convert the place builder to start from PlaceBase::Local.

Consider the following example

let t = (10, (10, (10, 10)));

let c = || {
    println!("{}", t.0.0.0);
};

Here the THIR expression for t.0.0.0 will be something like

* Field(0)
    * Field(0)
        * Field(0)
            * UpvarRef(t)

When capture_disjoint_fields is enabled, t.0.0.0 is captured and we won’t be able to figure out that it is captured until all the Field projections are applied.

Fields of Upvar

var_hir_id: HirId

HirId of the upvar

closure_def_id: DefId

DefId of the closure

closure_kind: ClosureKind

The trait closure implements, Fn, FnMut, FnOnce

Trait Implementations

impl Clone for PlaceBase

fn clone(&self) -> PlaceBase

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PlaceBase

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'tcx> From<PlaceBase> for PlaceBuilder<'tcx>

fn from(base: PlaceBase) -> Self

Performs the conversion.

impl PartialEq<PlaceBase> for PlaceBase

fn eq(&self, other: &PlaceBase) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &PlaceBase) -> bool

This method tests for !=.

impl Copy for PlaceBase

impl StructuralPartialEq for PlaceBase