Enum rustc_pattern_analysis::constructor::ConstructorSet

pub enum ConstructorSet {
    Single {
        empty: bool,
    },
    Variants {
        variants: IndexVec<VariantIdx, VariantVisibility>,
        non_exhaustive: bool,
    },
    Bool,
    Integers {
        range_1: IntRange,
        range_2: Option<IntRange>,
    },
    Slice {
        array_len: Option<usize>,
        subtype_is_empty: bool,
    },
    Unlistable,
    NoConstructors,
}

Describes the set of all constructors for a type. For details, in particular about the emptiness of constructors, see the top of the file.

In terms of division of responsibility, ConstructorSet::split handles all of the exhaustive_patterns feature.

Variants

Single

Fields

empty: bool

The type has a single constructor, e.g. &T or a struct. empty tracks whether the constructor is empty.

Variants

Fields

variants: IndexVec<VariantIdx, VariantVisibility>

non_exhaustive: bool

This type has the following list of constructors. If variants is empty and non_exhaustive is false, don’t use this; use NoConstructors instead.

Bool

Booleans.

Integers

Fields

range_1: IntRange

range_2: Option<IntRange>

The type is spanned by integer values. The range or ranges give the set of allowed values. The second range is only useful for char.

Slice

Fields

array_len: Option<usize>

subtype_is_empty: bool

The type is matched by slices. array_len is the compile-time length of the array, if known. If subtype_is_empty, all constructors are empty except possibly the zero-length slice [].

Unlistable

The constructors cannot be listed, and the type cannot be matched exhaustively. E.g. str, floats.

NoConstructors

The type has no constructors (not even empty ones). This is ! and empty enums.

Implementations

impl ConstructorSet

pub(crate) fn split<'a, 'tcx>( &self, pcx: &PatCtxt<'_, '_, 'tcx>, ctors: impl Iterator<Item = &'a Constructor<'tcx>> + Clone ) -> SplitConstructorSet<'tcx>

where 'tcx: 'a,

This analyzes a column of constructors to 1/ determine which constructors of the type (if any) are missing; 2/ split constructors to handle non-trivial intersections e.g. on ranges or slices. This can get subtle; see SplitConstructorSet for details of this operation and its invariants.

Trait Implementations

impl Debug for ConstructorSet

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

Formats the value using the given formatter.

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: 96 bytes

Size for each variant:

• Single: 9 bytes
• Variants: 40 bytes
• Bool: 0 bytes
• Integers: 96 bytes
• Slice: 32 bytes
• Unlistable: 0 bytes
• NoConstructors: 0 bytes