Enum ConstraintCategory

pub enum ConstraintCategory<'tcx> {
    Return(ReturnConstraint),
    Yield,
    UseAsConst,
    UseAsStatic,
    TypeAnnotation,
    Cast {
        is_implicit_coercion: bool,
        unsize_to: Option<Ty<'tcx>>,
    },
    ClosureBounds,
    CallArgument(Option<Ty<'tcx>>),
    CopyBound,
    SizedBound,
    Assignment,
    Usage,
    OpaqueType,
    ClosureUpvar(FieldIdx),
    Predicate(Span),
    Boring,
    BoringNoLocation,
    Internal,
    IllegalUniverse,
}

Outlives-constraints can be categorized to determine whether and why they are interesting (for error reporting). Order of variants indicates sort order of the category, thereby influencing diagnostic output.

See also rustc_const_eval::borrow_check::constraints.

Variants

Return(ReturnConstraint)

Yield

UseAsConst

UseAsStatic

TypeAnnotation

Cast

Fields

is_implicit_coercion: bool

Whether this cast is a coercion that was automatically inserted by the compiler.

unsize_to: Option<Ty<'tcx>>

Whether this is an unsizing coercion and if yes, this contains the target type. Region variables are erased to ReErased.

ClosureBounds

A constraint that came from checking the body of a closure.

We try to get the category that the closure used when reporting this.

CallArgument(Option<Ty<'tcx>>)

Contains the function type if available.

CopyBound

SizedBound

Assignment

Usage

A constraint that came from a usage of a variable (e.g. in an ADT expression like Foo { field: my_val })

OpaqueType

ClosureUpvar(FieldIdx)

Predicate(Span)

A constraint from a user-written predicate with the provided span, written on the item with the given DefId

Boring

A “boring” constraint (caused by the given location) is one that the user probably doesn’t want to see described in diagnostics, because it is kind of an artifact of the type system setup.

BoringNoLocation

Internal

A constraint that doesn’t correspond to anything the user sees.

IllegalUniverse

An internal constraint derived from an illegal universe relation.

Trait Implementations

impl<'tcx> Clone for ConstraintCategory<'tcx>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx> Debug for ConstraintCategory<'tcx>

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

Formats the value using the given formatter.

impl<'tcx, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for ConstraintCategory<'tcx>

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

impl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for ConstraintCategory<'tcx>

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

impl<'tcx> Hash for ConstraintCategory<'tcx>

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

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

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

impl<'tcx> Ord for ConstraintCategory<'tcx>

fn cmp(&self, __other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<'tcx> PartialEq for ConstraintCategory<'tcx>

fn eq(&self, other: &ConstraintCategory<'tcx>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'tcx> PartialOrd for ConstraintCategory<'tcx>

fn partial_cmp(&self, __other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

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

fn try_fold_with<__F: FallibleTypeFolder<TyCtxt<'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) -> 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 ConstraintCategory<'tcx>

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

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

impl<'tcx> Copy for ConstraintCategory<'tcx>

impl<'tcx> Eq for ConstraintCategory<'tcx>

impl<'tcx> StructuralPartialEq for ConstraintCategory<'tcx>

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:

• Return: 7 bytes
• Yield: 0 bytes
• UseAsConst: 0 bytes
• UseAsStatic: 0 bytes
• TypeAnnotation: 0 bytes
• Cast: 15 bytes
• ClosureBounds: 0 bytes
• CallArgument: 15 bytes
• CopyBound: 0 bytes
• SizedBound: 0 bytes
• Assignment: 0 bytes
• Usage: 0 bytes
• OpaqueType: 0 bytes
• ClosureUpvar: 7 bytes
• Predicate: 11 bytes
• Boring: 0 bytes
• BoringNoLocation: 0 bytes
• Internal: 0 bytes
• IllegalUniverse: 0 bytes