Struct rustc_middle::thir::Ascription
source · [−]pub struct Ascription<'tcx> {
pub user_ty: PatTyProj<'tcx>,
pub variance: Variance,
pub user_ty_span: Span,
}Fields
user_ty: PatTyProj<'tcx>variance: VarianceVariance to use when relating the type user_ty to the type of the value being
matched. Typically, this is Variance::Covariant, since the value being matched must
have a type that is some subtype of the ascribed type.
Note that this variance does not apply for any bindings within subpatterns. The type
assigned to those bindings must be exactly equal to the user_ty given here.
The only place where this field is not Covariant is when matching constants, where
we currently use Contravariant – this is because the constant type just needs to
be “comparable” to the type of the input value. So, for example:
match x { "foo" => .. }requires that &'static str <: T_x, where T_x is the type of x. Really, we should
probably be checking for a PartialEq impl instead, but this preserves the behavior
of the old type-check for now. See #57280 for details.
user_ty_span: SpanTrait Implementations
sourceimpl<'tcx> Clone for Ascription<'tcx>
impl<'tcx> Clone for Ascription<'tcx>
sourcefn clone(&self) -> Ascription<'tcx>
fn clone(&self) -> Ascription<'tcx>
Returns a copy of the value. Read more
1.0.0 · sourcefn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source. Read more
sourceimpl<'tcx> Debug for Ascription<'tcx>
impl<'tcx> Debug for Ascription<'tcx>
sourceimpl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Ascription<'tcx>
impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Ascription<'tcx>
fn hash_stable(
&self,
__hcx: &mut StableHashingContext<'__ctx>,
__hasher: &mut StableHasher
)
sourceimpl<'tcx> PartialEq<Ascription<'tcx>> for Ascription<'tcx>
impl<'tcx> PartialEq<Ascription<'tcx>> for Ascription<'tcx>
sourcefn eq(&self, other: &Ascription<'tcx>) -> bool
fn eq(&self, other: &Ascription<'tcx>) -> bool
This method tests for self and other values to be equal, and is used
by ==. Read more
sourcefn ne(&self, other: &Ascription<'tcx>) -> bool
fn ne(&self, other: &Ascription<'tcx>) -> bool
This method tests for !=.
impl<'tcx> Copy for Ascription<'tcx>
impl<'tcx> StructuralPartialEq for Ascription<'tcx>
Auto Trait Implementations
impl<'tcx> !RefUnwindSafe for Ascription<'tcx>
impl<'tcx> !Send for Ascription<'tcx>
impl<'tcx> !Sync for Ascription<'tcx>
impl<'tcx> Unpin for Ascription<'tcx>
impl<'tcx> !UnwindSafe for Ascription<'tcx>
Blanket Implementations
sourceimpl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T where
T: Copy,
impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T where
T: Copy,
fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut Self
fn allocate_from_iter<'a>(
arena: &'a Arena<'tcx>,
iter: impl IntoIterator<Item = Self>
) -> &'a mut [Self]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcepub fn borrow_mut(&mut self) -> &mut T
pub fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<Ctxt, T> DepNodeParams<Ctxt> for T where
Ctxt: DepContext,
T: for<'a> HashStable<StableHashingContext<'a>> + Debug,
impl<Ctxt, T> DepNodeParams<Ctxt> for T where
Ctxt: DepContext,
T: for<'a> HashStable<StableHashingContext<'a>> + Debug,
pub default fn fingerprint_style() -> FingerprintStyle
sourcepub default fn to_fingerprint(&self, tcx: Ctxt) -> Fingerprint
pub default fn to_fingerprint(&self, tcx: Ctxt) -> 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). Read more
pub default fn to_debug_str(&self, Ctxt) -> String
sourcepub default fn recover(
Ctxt,
&DepNode<<Ctxt as DepContext>::DepKind>
) -> Option<T>
pub default fn recover(
Ctxt,
&DepNode<<Ctxt as DepContext>::DepKind>
) -> Option<T>
This method tries to recover the query key from the given DepNode,
something which is needed when forcing DepNodes 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. Read more
sourceimpl<T> MaybeResult<T> for T
impl<T> MaybeResult<T> for T
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcepub fn to_owned(&self) -> T
pub fn to_owned(&self) -> T
Creates owned data from borrowed data, usually by cloning. Read more
sourcepub fn clone_into(&self, target: &mut T)
pub fn clone_into(&self, target: &mut T)
toowned_clone_into)Uses borrowed data to replace owned data, usually by cloning. Read more
impl<'a, T> Captures<'a> for T where
T: ?Sized,
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: 72 bytes