These opened archetypes need to be bound within their context, so any mapping out of
the context will need to be explicit and map to newly-created generic parameters.
When there are same-type constraints involving opaque archetype
parameters and generic parameters of the enclosing environment, a
nested type of an opaque type archetype might in fact refer to
something in the outer environment of the opaque type. Recognize this
case and perform substitutions on such types using the opaque type's
substitutions.
Nested archetypes are represented by their base archetype kinds (primary,
opened, or opaque type) with an interface type that is a nested type,
as represented by a DependentMemberType. This provides a more uniform
representation of archetypes throughout the frontend.
Form opened archetype types based on an interface type and existential
type, rather than assuming all OpenedArchetypeType instances only
represent the root. Sink the UUID, existential type, and actual creation
of the opened archetype into the opened generic environment, so we
consistently only create new archetype instances from the generic
environment. This slims down OpenedArchetypeType and makes it work
similarly to the other archetype kinds, as well as generalizing it
to support nested types.
Sink the existential type and UUID of an
As another step toward eliminating NestedArchetypeType, generalize the
representation, construction, and serialization of primary and sequence
archetypes to interface types, rather than generic parameter types.
Instead of storing nested archetypes hierarchically in `ArchetypeType`,
store them in a map (indexed by dependent member type) on the generic
environment itself. With this, we no longer need to create archetypes
for every type along the path, because archetypes are findable via
generic environment + interface type.
The refactoring that moved the substitution of the outer environment
into an opaque type archeptype into the generic environment eliminated
the need for the bound signature entirely, so remove it.
When forming the generic signature of a generic environment for opaque
types, substitute for the outer generic parameters based on the provided
substitution map. We weren't able to do this before because the
substitution cannot be performed when there are interface types or
type variables involved. However, the lazy construction of this
generic signature and use of other queries on opaque type archetypes
ensures that we don't form new generic signatures until we have
concrete types to work with.
This enables same-type constraints amongst different opaque result types
and their associated types.
Teach `GenericEnvironment` how to lazily create opaque type archetypes,
performing the contextual substitutions as required but without
building the "bound" generic signature until required. To get here,
augment `GenericEnvironment` with knowledge of the purpose of the
environment, whether it is for normal cases (any signature), an opened
existential type, or an opaque type. For opaque types, store the
opaque type declaration and substitution map, which we also use to
uniquely find the generic environment. Among other things, this
ensures that different opaque type archetypes within the same opaque
type declaration are properly sharing a generic environment, which
wasn't happening before.
This still doesn't handle the case where a non-concrete anchor has a
concrete parent; that requires switching the archetype representation
to be "flat".
Fixes <rdar://problem/84734584>.
Start treating the null {Can}GenericSignature as a regular signature
with no requirements and no parameters. This not only makes for a much
safer abstraction, but allows us to simplify a lot of the clients of
GenericSignature that would previously have to check for null before
using the abstraction.
Instead of using the recursiveConcreteType and recursiveSuperclass bits in
EquivalenceClass, store an ErrorType to the cached value before we begin
archetype construction. If a recursive call attempts to get the archetype
for the same type re-entrantly, we will return an ErrorType.
Instead of using the recursiveConcreteType and recursiveSuperclass bits in
EquivalenceClass, store an ErrorType to the cached value before we begin
archetype construction. If a recursive call attempts to get the archetype
for the same type re-entrantly, we will return an ErrorType.
Structurally prevent a number of common anti-patterns involving generic
signatures by separating the interface into GenericSignature and the
implementation into GenericSignatureBase. In particular, this allows
the comparison operators to be deleted which forces callers to
canonicalize the signature or ask to compare pointers explicitly.
We've fixed a number of bugs recently where callers did not expect
to get a null Type out of subst(). This occurs particularly often
in SourceKit, where the input AST is often invalid and the types
resulting from substitution are mostly used for display.
Let's fix all these potential problems in one fell swoop by changing
subst() to always return a Type, possibly one containing ErrorTypes.
Only a couple of places depended on the old behavior, and they were
easy enough to change from checking for a null Type to checking if
the result responds with true to hasError().
Also while we're at it, simplify a few call sites of subst().
