Module rustc_trait_selection::traits::project [−][src]
Expand description
Code for projecting associated types out of trait references.
Structs
Enums
When attempting to resolve <T as TraitRef>::Name …
Depending on the stage of compilation, we want projection to be more or less conservative.
Traits
Functions
In the case of a trait object like
<dyn Iterator<Item = ()> as Iterator>::Item we can use the existential
predicate in the trait object.
The first thing we have to do is scan through the parameter environment to see whether there are any projection predicates there that can answer this question.
In the case of a nested projection like <::FooT as Bar>::BarT, we may find
that the definition of Foo has some clues:
Locate the definition of an associated type in the specialization hierarchy, starting from the given impl.
Normalizes any associated type projections in value, replacing
them with a fully resolved type where possible. The return value
combines the normalized result and any additional obligations that
were incurred as result.
The guts of normalize: normalize a specific projection like <T as Trait>::Item. The result is always a type (and possibly
additional obligations). If ambiguity arises, which implies that
there are unresolved type variables in the projection, we will
substitute a fresh type variable $X and generate a new
obligation <T as Trait>::Item == $X for later.
If we are projecting <T as Trait>::Item, but T: Trait does not
hold. In various error cases, we cannot generate a valid
normalized projection. Therefore, we create an inference variable
return an associated obligation that, when fulfilled, will lead to
an error.
As normalize, but with a custom depth.
The guts of normalize: normalize a specific projection like <T as Trait>::Item. The result is always a type (and possibly
additional obligations). Returns None in the case of ambiguity,
which indicates that there are unbound type variables.
Evaluates constraints of the form:
Evaluates constraints of the form:
Computes the result of a projection type (if we can).