Struct Instance

pub struct Instance<'tcx> {
    pub def: InstanceKind<'tcx>,
    pub args: GenericArgsRef<'tcx>,
}

An InstanceKind along with the args that are needed to substitute the instance.

Monomorphization happens on-the-fly and no monomorphized MIR is ever created. Instead, this type simply couples a potentially generic InstanceKind with some args, and codegen and const eval will do all required instantiations as they run.

Note: the Lift impl is currently not used by rustc, but is used by rustc_codegen_cranelift when the jit feature is enabled.

Fields

def: InstanceKind<'tcx>

args: GenericArgsRef<'tcx>

Implementations

impl<'tcx> Instance<'tcx>

pub fn ty(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Ty<'tcx>

Returns the Ty corresponding to this Instance, with generic instantiations applied and lifetimes erased, allowing a ParamEnv to be specified for use during normalization.

pub fn upstream_monomorphization(&self, tcx: TyCtxt<'tcx>) -> Option<CrateNum>

Finds a crate that contains a monomorphization of this instance that can be linked to from the local crate. A return value of None means no upstream crate provides such an exported monomorphization.

This method already takes into account the global -Zshare-generics setting, always returning None if share-generics is off.

impl<'tcx> Instance<'tcx>

pub fn new(def_id: DefId, args: GenericArgsRef<'tcx>) -> Instance<'tcx>

pub fn mono(tcx: TyCtxt<'tcx>, def_id: DefId) -> Instance<'tcx>

pub fn def_id(&self) -> DefId

pub fn try_resolve( tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, def_id: DefId, args: GenericArgsRef<'tcx>, ) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed>

Resolves a (def_id, args) pair to an (optional) instance – most commonly, this is used to find the precise code that will run for a trait method invocation, if known.

Returns Ok(None) if we cannot resolve Instance to a specific instance. For example, in a context like this,

fn foo<T: Debug>(t: T) { ... }

trying to resolve Debug::fmt applied to T will yield Ok(None), because we do not know what code ought to run. (Note that this setting is also affected by the RevealMode in the parameter environment.)

Presuming that coherence and type-check have succeeded, if this method is invoked in a monomorphic context (i.e., like during codegen), then it is guaranteed to return Ok(Some(instance)), except for when the instance’s inputs hit the type size limit, in which case it may bail out and return Ok(None).

Returns Err(ErrorGuaranteed) when the Instance resolution process couldn’t complete due to errors elsewhere - this is distinct from Ok(None) to avoid misleading diagnostics when an error has already been/will be emitted, for the original cause

pub fn expect_resolve( tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, def_id: DefId, args: GenericArgsRef<'tcx>, span: Span, ) -> Instance<'tcx>

pub fn resolve_for_fn_ptr( tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, def_id: DefId, args: GenericArgsRef<'tcx>, ) -> Option<Instance<'tcx>>

pub fn expect_resolve_for_vtable( tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, def_id: DefId, args: GenericArgsRef<'tcx>, span: Span, ) -> Instance<'tcx>

pub fn resolve_closure( tcx: TyCtxt<'tcx>, def_id: DefId, args: GenericArgsRef<'tcx>, requested_kind: ClosureKind, ) -> Instance<'tcx>

pub fn resolve_drop_in_place(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Instance<'tcx>

pub fn resolve_async_drop_in_place( tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, ) -> Instance<'tcx>

pub fn fn_once_adapter_instance( tcx: TyCtxt<'tcx>, closure_did: DefId, args: GenericArgsRef<'tcx>, ) -> Instance<'tcx>

pub fn try_resolve_item_for_coroutine( tcx: TyCtxt<'tcx>, trait_item_id: DefId, trait_id: DefId, rcvr_args: GenericArgsRef<'tcx>, ) -> Option<Instance<'tcx>>

fn args_for_mir_body(&self) -> Option<GenericArgsRef<'tcx>>

Depending on the kind of InstanceKind, the MIR body associated with an instance is expressed in terms of the generic parameters of self.def_id(), and in other cases the MIR body is expressed in terms of the types found in the generic parameter array. In the former case, we want to instantiate those generic types and replace them with the values from the args when monomorphizing the function body. But in the latter case, we don’t want to do that instantiation, since it has already been done effectively.

This function returns Some(args) in the former case and None otherwise – i.e., if this function returns None, then the MIR body does not require instantiation during codegen.

pub fn instantiate_mir<T>( &self, tcx: TyCtxt<'tcx>, v: EarlyBinder<'tcx, &T>, ) -> T

where T: TypeFoldable<TyCtxt<'tcx>> + Copy,

pub fn instantiate_mir_and_normalize_erasing_regions<T>( &self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, v: EarlyBinder<'tcx, T>, ) -> T

where T: TypeFoldable<TyCtxt<'tcx>>,

pub fn try_instantiate_mir_and_normalize_erasing_regions<T>( &self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, v: EarlyBinder<'tcx, T>, ) -> Result<T, NormalizationError<'tcx>>

where T: TypeFoldable<TyCtxt<'tcx>>,

pub fn polymorphize(self, tcx: TyCtxt<'tcx>) -> Self

Returns a new Instance where generic parameters in instance.args are replaced by identity parameters if they are determined to be unused in instance.def.

Trait Implementations

impl<'tcx> Clone for Instance<'tcx>

fn clone(&self) -> Instance<'tcx>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx> Debug for Instance<'tcx>

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

Formats the value using the given formatter.

impl<'tcx, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for Instance<'tcx>

fn decode(__decoder: &mut __D) -> Self

impl<'tcx> Display for Instance<'tcx>

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

Formats the value using the given formatter.

impl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for Instance<'tcx>

fn encode(&self, __encoder: &mut __E)

impl<'tcx> EraseType for Instance<'tcx>

type Result = [u8; 32]

impl<'tcx> Hash for Instance<'tcx>

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<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Instance<'tcx>

fn hash_stable( &self, __hcx: &mut StableHashingContext<'__ctx>, __hasher: &mut StableHasher, )

impl<'tcx> Key for Instance<'tcx>

type Cache<V> = DefaultCache<Instance<'tcx>, V>

fn default_span(&self, tcx: TyCtxt<'_>) -> Span

In the event that a cycle occurs, if no explicit span has been given for a query with key self, what span should we use?

fn key_as_def_id(&self) -> Option<DefId>

If the key is a DefId or DefId–equivalent, return that DefId. Otherwise, return None.

fn ty_def_id(&self) -> Option<DefId>

impl<'tcx, '__lifted> Lift<TyCtxt<'__lifted>> for Instance<'tcx>

type Lifted = Instance<'__lifted>

fn lift_to_interner( self, __tcx: TyCtxt<'__lifted>, ) -> Option<Instance<'__lifted>>

impl<'tcx> PartialEq for Instance<'tcx>

fn eq(&self, other: &Instance<'tcx>) -> 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<'tcx> TypeFoldable<TyCtxt<'tcx>> for Instance<'tcx>

fn try_fold_with<__F: FallibleTypeFolder<TyCtxt<'tcx>>>( self, __folder: &mut __F, ) -> Result<Self, __F::Error>

The entry point for folding. To fold a value t with a folder f call: t.try_fold_with(f).

fn fold_with<F>(self, folder: &mut F) -> Self

where F: TypeFolder<I>,

A convenient alternative to try_fold_with for use with infallible folders. Do not override this method, to ensure coherence with try_fold_with.

impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Instance<'tcx>

fn visit_with<__V: TypeVisitor<TyCtxt<'tcx>>>( &self, __visitor: &mut __V, ) -> __V::Result

The entry point for visiting. To visit a value t with a visitor v call: t.visit_with(v).

impl<'tcx> Copy for Instance<'tcx>

impl<'tcx> Eq for Instance<'tcx>

impl<'tcx> StructuralPartialEq for Instance<'tcx>

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: 32 bytes