Type Alias Solution

pub type Solution = Solution<Interner>;

Aliased Type

enum Solution {
    Unique(Canonical<ConstrainedSubst<Interner>>),
    Ambig(Guidance<Interner>),
}

Variants

Unique(Canonical<ConstrainedSubst<Interner>>)

The goal indeed holds, and there is a unique value for all existential variables. In this case, we also record a set of lifetime constraints which must also hold for the goal to be valid.

Ambig(Guidance<Interner>)

The goal may be provable in multiple ways, but regardless we may have some guidance for type inference. In this case, we don’t return any lifetime constraints, since we have not “committed” to any particular solution yet.

Implementations

impl<I> Solution<I>

where I: Interner,

pub fn combine(self, other: Solution<I>, interner: I) -> Solution<I>

There are multiple candidate solutions, which may or may not agree on the values for existential variables; attempt to combine them. This operation does not depend on the order of its arguments.

This actually isn’t as precise as it could be, in two ways:

a. It might be that while there are multiple distinct candidates, they all agree about some things. To be maximally precise, we would compute the intersection of what they agree on. It’s not clear though that this is actually what we want Rust’s inference to do, and it’s certainly not what it does today.

b. There might also be an ambiguous candidate and a successful candidate, both with the same refined-goal. In that case, we could probably claim success, since if the conditions of the ambiguous candidate were met, we know the success would apply. Example: ?0: Clone yields ambiguous candidate Option<?0>: Clone and successful candidate Option<?0>: Clone.

But you get the idea.

pub fn is_trivial_and_always_true(&self, interner: I) -> bool

pub fn into_guidance(self) -> Guidance<I>

View this solution purely in terms of type inference guidance

pub fn constrained_subst( &self, interner: I, ) -> Option<Canonical<ConstrainedSubst<I>>>

Extract a constrained substitution from this solution, even if ambiguous.

pub fn definite_subst( &self, interner: I, ) -> Option<Canonical<ConstrainedSubst<I>>>

Determine whether this solution contains type information that must hold, and returns the subst in that case.

pub fn is_unique(&self) -> bool

pub fn is_ambig(&self) -> bool

pub fn display(&self, interner: I) -> SolutionDisplay<'_, I>

Trait Implementations

impl<I> Clone for Solution<I>

where I: Clone + Interner,

fn clone(&self) -> Solution<I>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<I> Debug for Solution<I>

where I: Debug + Interner,

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

Formats the value using the given formatter.

impl<I> HasInterner for Solution<I>

where I: Interner,

type Interner = I

The interner associated with the type.

impl<I> PartialEq for Solution<I>

where I: PartialEq + Interner,

fn eq(&self, other: &Solution<I>) -> 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<I> Eq for Solution<I>

where I: Eq + Interner,

impl<I> StructuralPartialEq for Solution<I>

where I: Interner,