Struct LayoutData

pub struct LayoutData<FieldIdx, VariantIdx>
where
    FieldIdx: Idx,
    VariantIdx: Idx,
{
    pub fields: FieldsShape<FieldIdx>,
    pub variants: Variants<FieldIdx, VariantIdx>,
    pub abi: Abi,
    pub largest_niche: Option<Niche>,
    pub align: AbiAndPrefAlign,
    pub size: Size,
    pub max_repr_align: Option<Align>,
    pub unadjusted_abi_align: Align,
}

Fields

fields: FieldsShape<FieldIdx>

Says where the fields are located within the layout.

variants: Variants<FieldIdx, VariantIdx>

Encodes information about multi-variant layouts. Even with Multiple variants, a layout still has its own fields! Those are then shared between all variants. One of them will be the discriminant, but e.g. coroutines can have more.

To access all fields of this layout, both fields and the fields of the active variant must be taken into account.

abi: Abi

The abi defines how this data is passed between functions, and it defines value restrictions via valid_range.

Note that this is entirely orthogonal to the recursive structure defined by variants and fields; for example, ManuallyDrop<Result<isize, isize>> has Abi::ScalarPair! So, even with non-Aggregate abi, fields and variants have to be taken into account to find all fields of this layout.

largest_niche: Option<Niche>

The leaf scalar with the largest number of invalid values (i.e. outside of its valid_range), if it exists.

align: AbiAndPrefAlign

size: Size

max_repr_align: Option<Align>

The largest alignment explicitly requested with repr(align) on this type or any field. Only used on i686-windows, where the argument passing ABI is different when alignment is requested, even if the requested alignment is equal to the natural alignment.

unadjusted_abi_align: Align

The alignment the type would have, ignoring any repr(align) but including repr(packed). Only used on aarch64-linux, where the argument passing ABI ignores the requested alignment in some cases.

Implementations

impl<FieldIdx, VariantIdx> LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Idx, VariantIdx: Idx,

pub fn is_aggregate(&self) -> bool

Returns true if this is an aggregate type (including a ScalarPair!)

pub fn is_uninhabited(&self) -> bool

Returns true if this is an uninhabited type

pub fn scalar<C>(cx: &C, scalar: Scalar) -> LayoutData<FieldIdx, VariantIdx>

where C: HasDataLayout,

impl<FieldIdx, VariantIdx> LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Idx, VariantIdx: Idx,

pub fn is_unsized(&self) -> bool

Returns true if the layout corresponds to an unsized type.

pub fn is_sized(&self) -> bool

pub fn is_1zst(&self) -> bool

Returns true if the type is sized and a 1-ZST (meaning it has size 0 and alignment 1).

pub fn is_zst(&self) -> bool

Returns true if the type is a ZST and not unsized.

Note that this does not imply that the type is irrelevant for layout! It can still have non-trivial alignment constraints. You probably want to use is_1zst instead.

pub fn eq_abi(&self, other: &LayoutData<FieldIdx, VariantIdx>) -> bool

Checks if these two Layout are equal enough to be considered “the same for all function call ABIs”. Note however that real ABIs depend on more details that are not reflected in the Layout; the PassMode need to be compared as well. Also note that we assume aggregates are passed via PassMode::Indirect or PassMode::Cast; more strict checks would otherwise be required.

Trait Implementations

impl<FieldIdx, VariantIdx> Clone for LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Clone + Idx, VariantIdx: Clone + Idx,

fn clone(&self) -> LayoutData<FieldIdx, VariantIdx>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<FieldIdx, VariantIdx> Debug for LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Idx, VariantIdx: Idx, FieldsShape<FieldIdx>: Debug, Variants<FieldIdx, VariantIdx>: Debug,

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

Formats the value using the given formatter.

impl<FieldIdx, VariantIdx> Hash for LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Hash + Idx, VariantIdx: Hash + Idx,

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

where __H: Hasher,

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<FieldIdx, VariantIdx, __CTX> HashStable<__CTX> for LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Idx + HashStable<__CTX>, VariantIdx: Idx + HashStable<__CTX>, __CTX: HashStableContext,

fn hash_stable( &self, __hcx: &mut __CTX, __hasher: &mut StableHasher<SipHasher128>, )

impl<FieldIdx, VariantIdx> PartialEq for LayoutData<FieldIdx, VariantIdx>

where FieldIdx: PartialEq + Idx, VariantIdx: PartialEq + Idx,

fn eq(&self, other: &LayoutData<FieldIdx, VariantIdx>) -> 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<FieldIdx, VariantIdx> Eq for LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Eq + Idx, VariantIdx: Eq + Idx,

impl<FieldIdx, VariantIdx> StructuralPartialEq for LayoutData<FieldIdx, VariantIdx>

where FieldIdx: Idx, VariantIdx: Idx,

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.