Struct rustc_middle::ty::adjustment::Adjustment

pub struct Adjustment<'tcx> {
    pub kind: Adjust<'tcx>,
    pub target: Ty<'tcx>,
}

Represents coercing a value to a different type of value.

We transform values by following a number of Adjust steps in order. See the documentation on variants of Adjust for more details.

Here are some common scenarios:

1. The simplest cases are where a pointer is not adjusted fat vs thin. Here the pointer will be dereferenced N times (where a dereference can happen to raw or borrowed pointers or any smart pointer which implements Deref, including Box<_>). The types of dereferences is given by autoderefs. It can then be auto-referenced zero or one times, indicated by autoref, to either a raw or borrowed pointer. In these cases unsize is false.

2. A thin-to-fat coercion involves unsizing the underlying data. We start with a thin pointer, deref a number of times, unsize the underlying data, then autoref. The ‘unsize’ phase may change a fixed length array to a dynamically sized one, a concrete object to a trait object, or statically sized struct to a dynamically sized one. E.g., &[i32; 4] -> &i32 is represented by:

   Deref(None) -> [i32; 4],
   Borrow(AutoBorrow::Ref) -> &[i32; 4],
   Unsize -> &[i32],

   Note that for a struct, the ‘deep’ unsizing of the struct is not recorded. E.g., struct Foo<T> { x: T } we can coerce &Foo<[i32; 4]> to &Foo<i32> The autoderef and -ref are the same as in the above example, but the type stored in unsize is Foo<[i32]>, we don’t store any further detail about the underlying conversions from [i32; 4] to [i32].

3. Coercing a Box<T> to Box<dyn Trait> is an interesting special case. In that case, we have the pointer we need coming in, so there are no autoderefs, and no autoref. Instead we just do the Unsize transformation. At some point, of course, Box should move out of the compiler, in which case this is analogous to transforming a struct. E.g., Box<[i32; 4]> -> Box<i32> is an Adjust::Unsize with the target Box<[i32]>.

Fields

kind: Adjust<'tcx>

target: Ty<'tcx>

Implementations

impl<'tcx> Adjustment<'tcx>

pub fn is_region_borrow(&self) -> bool

Trait Implementations

impl<'tcx> Clone for Adjustment<'tcx>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx> Debug for Adjustment<'tcx>

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

Formats the value using the given formatter.

impl<'tcx, __D: TyDecoder<'tcx>> Decodable<__D> for Adjustment<'tcx>

fn decode(__decoder: &mut __D) -> Result<Self, <__D as Decoder>::Error>

impl<'tcx, __E: TyEncoder<'tcx>> Encodable<__E> for Adjustment<'tcx>

fn encode(&self, __encoder: &mut __E) -> Result<(), <__E as Encoder>::Error>

impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Adjustment<'tcx>

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

impl<'a, 'tcx> Lift<'tcx> for Adjustment<'a>

type Lifted = Adjustment<'tcx>

fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>

impl<'tcx> TypeFoldable<'tcx> for Adjustment<'tcx>

fn super_fold_with<__F: TypeFolder<'tcx>>(self, __folder: &mut __F) -> Self

fn super_visit_with<__F: TypeVisitor<'tcx>>(
    &self,
    __folder: &mut __F
) -> ControlFlow<__F::BreakTy>

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

fn visit_with<V: TypeVisitor<'tcx>>(
    &self,
    visitor: &mut V
) -> ControlFlow<V::BreakTy>

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.

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

Returns true if this self has any regions that escape binder (and hence are not bound by it).

fn has_escaping_bound_vars(&self) -> bool

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

fn has_projections(&self) -> bool

fn has_opaque_types(&self) -> bool

fn references_error(&self) -> bool

fn has_param_types_or_consts(&self) -> bool

fn has_infer_regions(&self) -> bool

fn has_infer_types(&self) -> bool

fn has_infer_types_or_consts(&self) -> bool

fn needs_infer(&self) -> bool

fn has_placeholders(&self) -> bool

fn needs_subst(&self) -> bool

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.

fn has_erased_regions(&self) -> bool

fn has_erasable_regions(&self) -> bool

True if there are any un-erased free regions.

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.

fn has_late_bound_regions(&self) -> bool

True if there are any late-bound regions

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.