Struct Arg 

pub struct Arg {
    pub slot: Slot,
    pub layout: LayoutId,
}

One argument of a call: where the value is, and what it is.

A slot alone says where an operand begins and never how wide it is. A scalar is described by the Repr of the slot it sits in and a reference by the header of the object it names, but an inline struct or enum is a run of words with nothing attached to it at all — a Point in a frame is described by neither. So a callee that is polymorphic over the values it is handed had no way to read one: "{Point(x: 1)}" rendered the first word, a == b on two structs compared the first word, and the operations that put a whole value into a collection refused rather than store half of one.

Carrying the layout beside the slot answers all of them at once, and it is carried for every argument rather than for the calls that turned out to need it. A layout is what an argument is; which callee reads it is not the argument’s business, and one rule the verifier checks everywhere is worth more than the word this costs at the sites that could have done without.

Fields

slot: Slot

The first slot of the value location in the caller’s frame.

layout: LayoutId

The layout of that location, which is what says how wide it is.

Trait Implementations

impl Clone for Arg

fn clone(&self) -> Arg

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Arg

impl Debug for Arg

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

Formats the value using the given formatter.

impl Eq for Arg

impl Hash for Arg

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Arg

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Arg