# Struct rustc_middle::ty::Instance

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

Expand description

A monomorphized `InstanceDef`.

Monomorphization happens on-the-fly and no monomorphized MIR is ever created. Instead, this type simply couples a potentially generic `InstanceDef` 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: InstanceDef<'tcx>`§`args: GenericArgsRef<'tcx>`

## Implementations§

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### impl<'tcx> Instance<'tcx>

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#### 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.

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#### 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.

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### impl<'tcx> Instance<'tcx>

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

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

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#### pub fn def_id(&self) -> DefId

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#### pub fn 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,

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    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))`.

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

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

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

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

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

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

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

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

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

Depending on the kind of `InstanceDef`, 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.

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#### pub fn instantiate_mir<T>(&self, tcx: TyCtxt<'tcx>, v: EarlyBinder<&T>) -> T
where T: TypeFoldable<TyCtxt<'tcx>> + Copy,

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

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

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#### 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§

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

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

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl<'tcx> Debug for Instance<'tcx>

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

Formats the value using the given formatter. Read more
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### impl<'tcx, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for Instance<'tcx>

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

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

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

Formats the value using the given formatter. Read more
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### impl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for Instance<'tcx>

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

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

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#### type Result = [u8; 32]

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

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

Feeds this value into the given `Hasher`. Read more
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#### fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Instance<'tcx>

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

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

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#### type CacheSelector = DefaultCacheSelector<Instance<'tcx>>

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

If the key is a `DefId` or `DefId`–equivalent, return that `DefId`. Otherwise, return `None`.
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#### fn ty_def_id(&self) -> Option<DefId>

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

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#### type Lifted = Instance<'__lifted>

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

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

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#### fn eq(&self, other: &Instance<'tcx>) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### fn ne(&self, other: &Rhs) -> bool

This method tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Instance<'tcx>

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#### 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)`. Read more
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#### 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`.
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### impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Instance<'tcx>

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#### 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)`. Read more
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### impl<'tcx> Copy for Instance<'tcx>

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

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

## Auto Trait Implementations§

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### impl<'tcx> DynSend for Instance<'tcx>

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### impl<'tcx> DynSync for Instance<'tcx>

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### impl<'tcx> Freeze for Instance<'tcx>

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### impl<'tcx> !RefUnwindSafe for Instance<'tcx>

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### impl<'tcx> Send for Instance<'tcx>

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### impl<'tcx> Sync for Instance<'tcx>

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### impl<'tcx> Unpin for Instance<'tcx>

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### impl<'tcx> !UnwindSafe for Instance<'tcx>

## Blanket Implementations§

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### impl<T> Aligned for T

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#### const ALIGN: Alignment = _

Alignment of `Self`.
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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> AnyEq for T
where T: Any + PartialEq,

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#### fn equals(&self, other: &(dyn Any + 'static)) -> bool

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#### fn as_any(&self) -> &(dyn Any + 'static)

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### impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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#### fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut T

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#### fn allocate_from_iter<'a>( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T> ) -> &'a mut [T]

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### impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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#### fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut T

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#### fn allocate_from_iter<'a>( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T> ) -> &'a mut [T]

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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T, R> CollectAndApply<T, R> for T

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#### fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to `f(&iter.collect::<Vec<_>>())`.

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#### type Output = R

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### impl<Tcx, T> DepNodeParams<Tcx> for T
where Tcx: DepContext, T: for<'a> HashStable<StableHashingContext<'a>> + Debug,

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#### default fn fingerprint_style() -> FingerprintStyle

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#### default fn to_fingerprint(&self, tcx: Tcx) -> Fingerprint

This method turns the parameters of a DepNodeConstructor into an opaque Fingerprint to be used in DepNode. Not all DepNodeParams support being turned into a Fingerprint (they don’t need to if the corresponding DepNode is anonymous).
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#### default fn to_debug_str(&self, _: Tcx) -> String

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#### default fn recover(_: Tcx, _: &DepNode) -> Option<T>

This method tries to recover the query key from the given `DepNode`, something which is needed when forcing `DepNode`s during red-green evaluation. The query system will only call this method if `fingerprint_style()` is not `FingerprintStyle::Opaque`. It is always valid to return `None` here, in which case incremental compilation will treat the query as having changed instead of forcing it.
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Compare self to `key` and return `true` if they are equal.
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### impl<T> Filterable for T

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#### fn filterable( self, filter_name: &'static str ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

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

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### impl<P> IntoQueryParam<P> for P

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#### fn into_query_param(self) -> P

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### impl<'tcx, T> IsSuggestable<'tcx> for T
where T: TypeVisitable<TyCtxt<'tcx>> + TypeFoldable<TyCtxt<'tcx>>,

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#### fn is_suggestable(self, tcx: TyCtxt<'tcx>, infer_suggestable: bool) -> bool

Whether this makes sense to suggest in a diagnostic. Read more
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#### fn make_suggestable( self, tcx: TyCtxt<'tcx>, infer_suggestable: bool ) -> Option<T>

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### impl<T> MaybeResult<T> for T

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#### type Error = !

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#### fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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#### fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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### impl<T> Pointable for T

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#### const ALIGN: usize = _

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T> ToOwned for T
where T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<'tcx, T> ToPredicate<'tcx, T> for T

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#### fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

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### impl<T> ToString for T
where T: Display + ?Sized,

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#### default fn to_string(&self) -> String

Converts the given value to a `String`. Read more
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<I, T> TypeVisitableExt<I> for T
where I: Interner, T: TypeVisitable<I>,

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#### fn has_type_flags(&self, flags: TypeFlags) -> bool

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#### fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool

Returns `true` if `self` has any late-bound regions that are either bound by `binder` or bound by some binder outside of `binder`. If `binder` is `ty::INNERMOST`, this indicates whether there are any late-bound regions that appear free.
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#### fn error_reported(&self) -> Result<(), <I as Interner>::ErrorGuaranteed>

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#### fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool

Returns `true` if this type has any regions that escape `binder` (and hence are not bound by it).
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#### fn has_escaping_bound_vars(&self) -> bool

Return `true` if this type has regions that are not a part of the type. For example, `for<'a> fn(&'a i32)` return `false`, while `fn(&'a i32)` would return `true`. The latter can occur when traversing through the former. Read more
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#### fn has_projections(&self) -> bool

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#### fn has_inherent_projections(&self) -> bool

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#### fn has_opaque_types(&self) -> bool

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#### fn has_coroutines(&self) -> bool

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#### fn references_error(&self) -> bool

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#### fn has_non_region_param(&self) -> bool

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#### fn has_infer_regions(&self) -> bool

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#### fn has_infer_types(&self) -> bool

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#### fn has_non_region_infer(&self) -> bool

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#### fn has_infer(&self) -> bool

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#### fn has_placeholders(&self) -> bool

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#### fn has_non_region_placeholders(&self) -> bool

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#### fn has_param(&self) -> bool

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#### fn has_free_regions(&self) -> bool

“Free” regions in this context means that it has any region that is not (a) erased or (b) late-bound.
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#### fn has_erased_regions(&self) -> bool

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#### fn has_erasable_regions(&self) -> bool

True if there are any un-erased free regions.
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#### fn is_global(&self) -> bool

Indicates whether this value references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching.
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#### fn has_bound_regions(&self) -> bool

True if there are any late-bound regions
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#### fn has_non_region_bound_vars(&self) -> bool

True if there are any late-bound non-region variables
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#### fn has_bound_vars(&self) -> bool

True if there are any bound variables
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#### fn still_further_specializable(&self) -> bool

Indicates whether this value still has parameters/placeholders/inference variables which could be replaced later, in a way that would change the results of `impl` specialization.
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### impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

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#### default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed ) -> T

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

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### impl<T> ErasedDestructor for T
where T: 'static,

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### impl<T> MaybeSendSync for T
where T: Send + Sync,

## 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