Enum PatKind

pub enum PatKind<'tcx> {
    Wild,
    AscribeUserType {
        ascription: Ascription<'tcx>,
        subpattern: Box<Pat<'tcx>>,
    },
    Binding {
        name: Symbol,
        mode: BindingMode,
        var: LocalVarId,
        ty: Ty<'tcx>,
        subpattern: Option<Box<Pat<'tcx>>>,
        is_primary: bool,
    },
    Variant {
        adt_def: AdtDef<'tcx>,
        args: GenericArgsRef<'tcx>,
        variant_index: VariantIdx,
        subpatterns: Vec<FieldPat<'tcx>>,
    },
    Leaf {
        subpatterns: Vec<FieldPat<'tcx>>,
    },
    Deref {
        subpattern: Box<Pat<'tcx>>,
    },
    DerefPattern {
        subpattern: Box<Pat<'tcx>>,
        mutability: Mutability,
    },
    Constant {
        value: Const<'tcx>,
    },
    ExpandedConstant {
        def_id: DefId,
        is_inline: bool,
        subpattern: Box<Pat<'tcx>>,
    },
    Range(Box<PatRange<'tcx>>),
    Slice {
        prefix: Box<[Box<Pat<'tcx>>]>,
        slice: Option<Box<Pat<'tcx>>>,
        suffix: Box<[Box<Pat<'tcx>>]>,
    },
    Array {
        prefix: Box<[Box<Pat<'tcx>>]>,
        slice: Option<Box<Pat<'tcx>>>,
        suffix: Box<[Box<Pat<'tcx>>]>,
    },
    Or {
        pats: Box<[Box<Pat<'tcx>>]>,
    },
    Never,
    Error(ErrorGuaranteed),
}

Variants

Wild

A wildcard pattern: _.

AscribeUserType

Fields

ascription: Ascription<'tcx>

subpattern: Box<Pat<'tcx>>

Binding

x, ref x, x @ P, etc.

Fields

name: Symbol

mode: BindingMode

var: LocalVarId

ty: Ty<'tcx>

subpattern: Option<Box<Pat<'tcx>>>

is_primary: bool

Is this the leftmost occurrence of the binding, i.e., is var the HirId of this pattern?

Variant

Foo(...) or Foo{...} or Foo, where Foo is a variant name from an ADT with multiple variants.

Fields

adt_def: AdtDef<'tcx>

args: GenericArgsRef<'tcx>

variant_index: VariantIdx

subpatterns: Vec<FieldPat<'tcx>>

Leaf

(...), Foo(...), Foo{...}, or Foo, where Foo is a variant name from an ADT with a single variant.

Fields

subpatterns: Vec<FieldPat<'tcx>>

Deref

box P, &P, &mut P, etc.

Fields

subpattern: Box<Pat<'tcx>>

DerefPattern

Deref pattern, written box P for now.

Fields

subpattern: Box<Pat<'tcx>>

mutability: Mutability

Constant

One of the following:

• &str/&[u8] (represented as a valtree), which will be handled as a string/slice pattern and thus exhaustiveness checking will detect if you use the same string/slice twice in different patterns.
• integer, bool, char or float (represented as a valtree), which will be handled by exhaustiveness to cover exactly its own value, similar to &str, but these values are much simpler.
• String, if string_deref_patterns is enabled.

Fields

value: Const<'tcx>

ExpandedConstant

Pattern obtained by converting a constant (inline or named) to its pattern representation using const_to_pat.

Fields

def_id: DefId

DefId of the constant, we need this so that we have a reference that can be used by unsafety checking to visit nested unevaluated constants and for diagnostics. If the DefId doesn’t correspond to a local crate, it points at the const item.

is_inline: bool

If false, then def_id points at a const item, otherwise it corresponds to a local inline const.

subpattern: Box<Pat<'tcx>>

If the inline constant is used in a range pattern, this subpattern represents the range (if both ends are inline constants, there will be multiple InlineConstant wrappers).

Otherwise, the actual pattern that the constant lowered to. As with other constants, inline constants are matched structurally where possible.

Range(Box<PatRange<'tcx>>)

Slice

Matches against a slice, checking the length and extracting elements. irrefutable when there is a slice pattern and both prefix and suffix are empty. e.g., &[ref xs @ ..].

Fields

prefix: Box<[Box<Pat<'tcx>>]>

slice: Option<Box<Pat<'tcx>>>

suffix: Box<[Box<Pat<'tcx>>]>

Array

Fixed match against an array; irrefutable.

Fields

prefix: Box<[Box<Pat<'tcx>>]>

slice: Option<Box<Pat<'tcx>>>

suffix: Box<[Box<Pat<'tcx>>]>

Or

An or-pattern, e.g. p | q. Invariant: pats.len() >= 2.

Fields

pats: Box<[Box<Pat<'tcx>>]>

Never

A never pattern !.

Error(ErrorGuaranteed)

An error has been encountered during lowering. We probably shouldn’t report more lints related to this pattern.

Trait Implementations

impl<'tcx> Clone for PatKind<'tcx>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx> Debug for PatKind<'tcx>

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

Formats the value using the given formatter.

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

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

impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for PatKind<'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).

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: 48 bytes

Size for each variant:

• Wild: 0 bytes
• AscribeUserType: 48 bytes
• Binding: 40 bytes
• Variant: 48 bytes
• Leaf: 32 bytes
• Deref: 16 bytes
• DerefPattern: 24 bytes
• Constant: 48 bytes
• ExpandedConstant: 32 bytes
• Range: 16 bytes
• Slice: 48 bytes
• Array: 48 bytes
• Or: 24 bytes
• Never: 0 bytes
• Error: 0 bytes