Enum rustc_trait_selection::infer::region_constraints::VerifyBound

pub enum VerifyBound<'tcx> {
    IfEq(Binder<TyCtxt<'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<TyCtxt<'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<(), Error>

Formats the value using the given formatter.

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

fn try_fold_with<__F>( self, __folder: &mut __F, ) -> Result<VerifyBound<'tcx>, <__F as FallibleTypeFolder<TyCtxt<'tcx>>>::Error>

where __F: FallibleTypeFolder<TyCtxt<'tcx>>,

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) -> 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.

impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for VerifyBound<'tcx>

fn visit_with<__V>( &self, __visitor: &mut __V, ) -> <__V as TypeVisitor<TyCtxt<'tcx>>>::Result

where __V: TypeVisitor<TyCtxt<'tcx>>,

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

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