Module rustc_trait_selection::infer
source · Modules
A nice interface for working with the infcx. The basic idea is to
do
infcx.at(cause, param_env), which sets the “cause” of the
operation as well as the surrounding parameter environment. Then
you can do something like .sub(a, b) or .eq(a, b) to create a
subtype or equality relationship respectively. The first argument
is always the “expected” output from the POV of diagnostics.Canonicalization is the key to constructing a query in the
middle of type inference. Ordinarily, it is not possible to store
types from type inference in query keys, because they contain
references to inference variables whose lifetimes are too short
and so forth. Canonicalizing a value T1 using
canonicalize_query
produces two things:Error Reporting Code for the inference engine
This module handles the relationships between “free regions”, i.e., lifetime parameters.
Ordinarily, free regions are unrelated to one another, but they can be related via implied
or explicit bounds. In that case, we track the bounds using the
TransitiveRelation type,
and use that to decide when one free region outlives another, and so forth.Lattice variables
This code is kind of an alternate way of doing subtyping,
supertyping, and type equating, distinct from the
combine.rs
code but very similar in its effect and design. Eventually the two
ought to be merged. This code is intended for use in NLL and chalk.Various code related to computing outlives relations.
See
README.md.Structs
A temporary returned by
tcx.infer_ctxt(). This is necessary
for multiple InferCtxt to share the same in_progress_typeck_results
without using Rc or something similar.This type contains all the things within
InferCtxt that sit within a
RefCell and are involved with taking/rolling back snapshots. Snapshot
operations are hot enough that we want only one call to borrow_mut per
call to start_snapshot and rollback_to.See the
region_obligations field for more information.The trace designates the path through inference that we took to
encounter an error or subtyping constraint.
Enums
Times when we replace late-bound regions with variables:
Reasons to create a region inference variable
The origin of a
r1 <= r2 constraint.Helper for
ty_or_const_infer_var_changed (see comment on that), currently
used only for traits::fulfill’s list of stalled_on inference variables.See the
error_reporting module for more details.