pub use self::LateBoundRegionConversionTime::*;
pub use self::RegionVariableOrigin::*;
pub use self::SubregionOrigin::*;
pub use self::ValuePairs::*;
A nice interface for working with the infcx. The basic idea is to
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
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
and use that to decide when one free region outlives another, and so forth.
Freshening is the process of replacing unknown variables with fresh types. The idea is that the type, after freshening, contains no inference variables but instead contains either a value for each variable or fresh “arbitrary” types wherever a variable would have been.
Helper routines for higher-ranked things. See the
doc module at
the end of the file for details.
Lexical region resolution.
This code is kind of an alternate way of doing subtyping,
supertyping, and type equating, distinct from the
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.
Helper type of a temporary returned by
Necessary because we can’t write the following bound:
F: for<'b, 'tcx> where 'tcx FnOnce(InferCtxt<'b, 'tcx>).
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
region_obligations field for more information.
The trace designates the path through inference that we took to encounter an error or subtyping constraint.
Times when we replace late-bound regions with variables:
Reasons to create a region inference variable
How we should handle region solving.
The origin of a
r1 <= r2 constraint.
ty_or_const_infer_var_changed (see comment on that), currently
used only for
traits::fulfill’s list of
stalled_on inference variables.
error_reporting module for more details.