Instance in rustc_middle::ty - Rust
Description: An `InstanceKind` along with the args that are needed to substitute the instance.

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## Instance

# Struct Instance

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

Expand description

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§

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

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#### pub fn ty(&self, tcx: TyCtxt<'tcx>, typing_env: TypingEnv<'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_raw(def_id: DefId, args: GenericArgsRef<'tcx>) -> Instance<'tcx>

Creates a new `InstanceKind::Item` from the `def_id` and `args`.

Note that this item corresponds to the body of `def_id` directly, which likely does not make sense for trait items which need to be resolved to an implementation, and which may not even have a body themselves. Usages of this function should probably use `Instance::expect_resolve`, or if run in a polymorphic environment or within a lint (that may encounter ambiguity) `Instance::try_resolve` instead.

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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 try_resolve( tcx: TyCtxt<'tcx>, typing_env: TypingEnv<'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. This should only be used for functions and consts. If you want to resolve an associated type, use `TyCtxt::try_normalize_erasing_regions`.

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. This setting is also affected by the current `TypingMode` of the 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

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

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

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#### pub fn expect_resolve_for_vtable( tcx: TyCtxt<'tcx>, typing_env: TypingEnv<'tcx>, def_id: DefId, args: GenericArgsRef<'tcx>, span: Span, ) -> 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 resolve_async_drop_in_place( tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, ) -> Instance<'tcx>

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#### pub fn resolve_async_drop_in_place_poll( tcx: TyCtxt<'tcx>, def_id: DefId, 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 `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.

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#### pub fn instantiate_mir<T>( &self, tcx: TyCtxt<'tcx>, v: EarlyBinder<'tcx, &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>, typing_env: TypingEnv<'tcx>, v: EarlyBinder<'tcx, 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>, typing_env: TypingEnv<'tcx>, v: EarlyBinder<'tcx, T>, ) -> Result<T, NormalizationError<'tcx>>
where T: TypeFoldable<TyCtxt<'tcx>>,

## Trait Implementations§

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

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

Returns a duplicate 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<'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<'tcx>> Encodable<__E> for Instance<'tcx>

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

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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 IntoDiagArg for Instance<'_>

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#### fn into_diag_arg(self, path: &mut Option<PathBuf>) -> DiagArgValue

Convert `Self` into a `DiagArgValue` suitable for rendering in a diagnostic. Read more
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### impl<'tcx, '__lifted> Lift<TyCtxt<'__lifted>> for Instance<'tcx>

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

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#### fn lift_to_interner( 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

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

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl<'tcx, P: Printer<'tcx> + Write> Print<'tcx, P> for Instance<'tcx>

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#### fn print(&self, cx: &mut P) -> Result<(), PrintError>

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### impl<'tcx> QueryKey for 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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#### type Cache<V> = DefaultCache<Self, V>

The type of in-memory cache to use for queries with this key type. Read more
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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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### 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: TypeFolder<TyCtxt<'tcx>>>(self, __folder: &mut __F) -> Self

The entry point for folding. To fold a value `t` with a folder `f` call: `t.fold_with(f)`. Read more
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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> UnsafeUnpin 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(self, arena: &'tcx Arena<'tcx>) -> &'tcx mut T

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

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

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

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#### fn allocate_from_iter( arena: &'tcx Arena<'tcx>, iter: impl IntoIterator<Item = T>, ) -> &'tcx 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> CloneToUninit for T
where T: Clone,

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#### unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (`clone_to_uninit`)
Performs copy-assignment from `self` to `dest`. 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> DepNodeKey<'tcx> for T
where T: for<'a> HashStable<StableHashingContext<'a>> + Debug,

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#### default fn key_fingerprint_style() -> KeyFingerprintStyle

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#### default fn to_fingerprint(&self, tcx: TyCtxt<'tcx>) -> Fingerprint

This method turns a query key into an opaque `Fingerprint` to be used in `DepNode`.
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#### default fn try_recover_key(_: TyCtxt<'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<T> DynClone for T
where T: Clone,

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#### fn __clone_box(&self, _: Private) -> *mut ()

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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> 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<T> IntoEither for T

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#### fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts `self` into a `Left` variant of `Either<Self, Self>` if `into_left` is `true`. Converts `self` into a `Right` variant of `Either<Self, Self>` otherwise. Read more
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#### fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts `self` into a `Left` variant of `Either<Self, Self>` if `into_left(&self)` returns `true`. Converts `self` into a `Right` variant of `Either<Self, Self>` otherwise. Read more
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### impl<K> IntoQueryKey<K> for K

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#### fn into_query_key(self) -> K

Argument conversion from `Self` to `K`. This should always be a very cheap conversion, e.g. `LocalDefId::to_def_id`.
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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, placeholder: Option<Ty<'tcx>>, ) -> 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<T> ToString for T
where T: Display + ?Sized,

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#### 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 non_region_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_aliases(&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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#### fn has_non_region_error(&self) -> bool

True if a type or const error is reachable
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### impl<I, T, U> Upcast<I, U> for T
where U: UpcastFrom<I, T>,

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#### fn upcast(self, interner: I) -> U

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### impl<I, T> UpcastFrom<I, T> for T

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#### fn upcast_from(from: T, _tcx: I) -> T

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

## 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