As part of generating the regions, if you enable -Zdump-mir=nll,
we will generate an annotated copy of the MIR that includes the
state of region inference. This code handles emitting the region
context internal state.
This module provides linkage between RegionInferenceContext and
rustc_graphviz traits, specialized to attaching borrowck analysis
data to rendered labels.
Each time that apply_member_constraint is successful, it appends
one of these structs to the member_constraints_applied field.
This is used in error reporting to trace out what happened.
A “type test” corresponds to an outlives constraint between a type
and a lifetime, like T: 'x or <T as Foo>::Bar: 'x. They are
translated from the Verify region constraints in the ordinary
inference context.