Returns the requirements for clause
to be well-formed.
Points the cause span of a super predicate at the relevant associated type.
Given an object type like SomeTrait + Send
, computes the lifetime
bounds that must hold on the elided self type. These are derived
from the declarations of SomeTrait
, Send
, and friends – if
they declare trait SomeTrait : 'static
, for example, then
'static
would appear in the list. The hard work is done by
infer::required_region_bounds
, see that for more information.
Returns the set of obligations needed to make arg
well-formed.
If arg
contains unresolved inference variables, this may include
further WF obligations. However, if arg
IS an unresolved
inference variable, returns None
, because we are not able to
make any progress at all. This is to prevent “livelock” where we
say “$0 is WF if $0 is WF”.
Given a set of predicates that apply to an object type, returns
the region bounds that the (erased) Self
type must
outlive. Precisely because the Self
type is erased, the
parameter erased_self_ty
must be supplied to indicate what type
has been used to represent Self
in the predicates
themselves. This should really be a unique type; FreshTy(0)
is a
popular choice.
Returns the obligations that make this trait reference
well-formed. For example, if there is a trait Set
defined like
trait Set<K: Eq>
, then the trait bound Foo: Set<Bar>
is WF
if Bar: Eq
.
Compute the predicates that are required for a type to be well-formed.