Trait Resolution. See the rustc-dev-guide for more information on how this works.
- engine 🔒
- project 🔒Code for projecting associated types out of trait references.
- Experimental types for the trait query interface. The methods defined in this module are all based on canonicalization, which makes a canonical query by replacing unbound inference variables and regions, so that results can be reused more broadly. The providers for the queries defined here can be found in
- Candidate selection. See the rustc dev guide for more information on how this works.
- Identifies a particular impl in the source, along with a set of substitutions from the impl’s type/lifetime parameters. The
nestedvector corresponds to the nested obligations attached to the impl’s type parameters.
Obligationrepresents some trait reference (e.g.,
i32: Eq) for which the “impl_source” must be found. The process of finding an “impl_source” is called “resolving” the
Obligation. This process consists of either identifying an
impl Eq for i32) that satisfies the obligation, or else finding a bound that is in scope. The eventual result is usually a
- The reason why we incurred this obligation; used for error reporting.
- The projection cache. Unlike the standard caches, this can include infcx-dependent type variables, therefore we have to roll the cache back each time we roll a snapshot back, to avoid assumptions on yet-unresolved inference variables. Types with placeholder regions also have to be removed when the respective snapshot ends.
- These are the error cases for
- Defines the treatment of opaque types in a given inference context.
- The result of trait evaluation. The order is important here as the evaluation of a list is the maximum of the evaluations.
- Given the successful resolution of an obligation, the
ImplSourceindicates where the impl comes from.
- Whether a value can be extracted into a const. Used for diagnostics around array repeat expressions.
- Reasons a method might not be object-safe.
- Indicates that trait evaluation caused overflow and in which pass.
- Depending on the stage of compilation, we want projection to be more or less conservative.
- The ‘location’ at which we try to perform HIR-based wf checking. This information is used to obtain an
hir::Ty, which we can walk in order to obtain precise spans for any ‘nested’ types (e.g.
- When performing resolution, it is typically the case that there can be one of three outcomes: