pub(crate) enum PlaceBase {
    Local(Local),
    Upvar {
        var_hir_id: LocalVarId,
        closure_def_id: LocalDefId,
    },
}
Expand description

The “outermost” place that holds this value.

Variants

Local(Local)

Denotes the start of a Place.

Upvar

Fields

var_hir_id: LocalVarId

HirId of the upvar

closure_def_id: LocalDefId

DefId of the closure

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.

Trait Implementations

Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more
Converts to this type from the input type.
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.

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: 12 bytes

Size for each variant:

  • Local: 4 bytes
  • Upvar: 12 bytes