Enum Predicate 

pub enum Predicate {
    Flag(Flag),
    Match(NameValue),
    Not(Box<Predicate>),
    All(ThinVec<Predicate>),
    Any(ThinVec<Predicate>),
}

Predicate(s) in #[rustc_on_unimplemented]’s on filter. See OnUnimplementedCondition.

It is similar to the predicate in the cfg attribute, and may contain nested predicates.

Variants

Flag(Flag)

A condition like on(crate_local).

Match(NameValue)

A match, like on(Rhs = "Whatever").

Not(Box<Predicate>)

Negation, like on(not($pred)).

All(ThinVec<Predicate>)

True if all predicates are true, like on(all($a, $b, $c)).

Any(ThinVec<Predicate>)

True if any predicate is true, like on(any($a, $b, $c)).

Implementations

impl Predicate

pub fn eval(&self, eval: &mut impl FnMut(FlagOrNv<'_>) -> bool) -> bool

pub fn visit_params(&self, span: Span, visit: &mut impl FnMut(Symbol, Span))

Trait Implementations

impl Clone for Predicate

fn clone(&self) -> Predicate

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Predicate

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

Formats the value using the given formatter.

impl<__D: SpanDecoder> Decodable<__D> for Predicate

fn decode(__decoder: &mut __D) -> Self

impl<__E: SpanEncoder> Encodable<__E> for Predicate

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

impl<__CTX> HashStable<__CTX> for Predicate

where __CTX: HashStableContext,

fn hash_stable(&self, __hcx: &mut __CTX, __hasher: &mut StableHasher)

impl PrintAttribute for Predicate

fn should_render(&self) -> bool

Whether or not this will render as something meaningful, or if it’s skipped (which will force the containing struct to also skip printing a comma and the field name).

fn print_attribute(&self, __p: &mut Printer)

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: 16 bytes

Size for each variant:

• Flag: 1 byte
• Match: 16 bytes
• Not: 8 bytes
• All: 8 bytes
• Any: 8 bytes