Enum rustc_infer::infer::region_constraints::VerifyBound

pub enum VerifyBound<'tcx> {
    IfEq(Binder<'tcx, VerifyIfEq<'tcx>>),
    OutlivedBy(Region<'tcx>),
    IsEmpty,
    AnyBound(Vec<VerifyBound<'tcx>>),
    AllBounds(Vec<VerifyBound<'tcx>>),
}

Describes the things that some GenericKind value G is known to outlive. Each variant of VerifyBound can be thought of as a function:

fn(min: Region) -> bool { .. }

where true means that the region min meets that G: min. (False means nothing.)

So, for example, if we have the type T and we have in scope that T: 'a and T: 'b, then the verify bound might be:

fn(min: Region) -> bool {
   ('a: min) || ('b: min)
}

This is described with an AnyRegion('a, 'b) node.

Variants

IfEq(Binder<'tcx, VerifyIfEq<'tcx>>)

See VerifyIfEq docs

OutlivedBy(Region<'tcx>)

Given a region R, expands to the function:

fn(min) -> bool {
    R: min
}

This is used when we can establish that G: R – therefore, if R: min, then by transitivity G: min.

IsEmpty

Given a region R, true if it is 'empty.

AnyBound(Vec<VerifyBound<'tcx>>)

Given a set of bounds B, expands to the function:

fn(min) -> bool {
    exists (b in B) { b(min) }
}

In other words, if we meet some bound in B, that suffices. This is used when all the bounds in B are known to apply to G.

AllBounds(Vec<VerifyBound<'tcx>>)

Given a set of bounds B, expands to the function:

fn(min) -> bool {
    forall (b in B) { b(min) }
}

In other words, if we meet all bounds in B, that suffices. This is used when some bound in B is known to suffice, but we don’t know which.

Implementations

impl<'tcx> VerifyBound<'tcx>

pub fn must_hold(&self) -> bool

pub fn cannot_hold(&self) -> bool

pub fn or(self, vb: VerifyBound<'tcx>) -> VerifyBound<'tcx>

Trait Implementations

impl<'tcx> Clone for VerifyBound<'tcx>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx> Debug for VerifyBound<'tcx>

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

Formats the value using the given formatter.

impl<'tcx> TypeFoldable<'tcx> for VerifyBound<'tcx>

fn try_fold_with<__F: FallibleTypeFolder<'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) -> Selfwhere
    F: TypeFolder<'tcx>,

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<'tcx> for VerifyBound<'tcx>

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

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

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 type has any regions that escape binder (and hence are not bound by it).

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.

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

fn has_projections(&self) -> bool

fn has_opaque_types(&self) -> bool

fn has_generators(&self) -> bool

fn references_error(&self) -> bool

fn error_reported(&self) -> Result<(), ErrorGuaranteed>

fn has_non_region_param(&self) -> bool

fn has_infer_regions(&self) -> bool

fn has_infer_types(&self) -> bool

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

True if there are any late-bound non-region variables

fn has_late_bound_vars(&self) -> bool

True if there are any late-bound variables

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.

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

Size for each variant:

• IfEq: 24 bytes
• OutlivedBy: 8 bytes
• IsEmpty: 0 bytes
• AnyBound: 24 bytes
• AllBounds: 24 bytes