Each nested archetype X.Y corresponds to an associated type named 'Y'
within one of the protocols to which X conforms. Record the associated
type within the archetype itself. When performing type substitutions,
use that associated type to extract the corresponding type witness
rather than looking for the type itself. This is technically more
correct (since we used the type witness for type checking), and a step
toward pulling type substitutions into the AST.
Swift SVN r7624
We previously relied on the type checker to fill in the implementation
types (swift.Slice<T> and swift.Optional<T>, respectively), which
limited our ability to perform type transformations in the AST. Now,
the AST knows how to form these implementation types on demand.
Swift SVN r7587
This breaks the type-canonicalization link between a generic parameter
type and the archetype to which it maps. Generic type parameter types
are now separate entities (that can eventually be canonicalized) from
archetypes (rather than just being sugar).
Most of the front end still traffics in archetypes. As a step away
from this, allow us to type-check the generic parameter list's types
prior to wiring the generic type parameter declarations to archetypes,
using the new "dependent" member type to describe assocaited
types. The archetype builder understands dependent member types and
uses them to map down to associated types when building archetypes.
Once we have assigned archetypes, we revert the dependent identifier
types within the generic parameter list to an un-type-checked state
and do the type checking again in the presence of archetypes, so that
nothing beyond the generic-parameter-list checking code has to deal
with dependent types. We'll creep support out to other dependent types
elsewhere over time.
Swift SVN r7462
Previously, we were creating the type corresponding to
class/struct/union declarations as part of creating the declaration
node, which happens at parse time. The main problem with this (at the
moment) occurs with nested nominal types, where we'd end up with the
wrong "parent" type when the type was nested inside an extension
(because the extension hadn't been resolved at the time we accessed
the parent's type). Amusingly, only code completion observed this,
because the canonical type system hid the problem. The churn in the
code-completion tests come from the fact that we now have the proper
declared type for class/struct/union declarations within extensions.
Take a step toward order-independent type checking by setting the type
of a class/struct/union declaration in type checking when we either
find the declaration (e.g., due to name lookup) or walk to the
declaration (in our walk of the whole translation unit to type-check
it), extending the existing TypeChecker::validateTypeDecl() entry
point and adding a few more callers.
The removeShadowedDecls() hack is awful; this needs to move out to the
callers, which should be abstracted better in the type checker anyway.
Incremental, non-obvious step toward fixing the representation of
polymorphic function types. This yak has a *lot* of hair.
Swift SVN r7444
Another baby step toward a proper canonical form for polymorphic
function types: generic parameters will eventually be uniquable by
their depth and index.
Swift SVN r7380
Previously, TypeAliasDecl was used for typealiases, generic
parameters, and assocaited types, which is hideous and the source of
much confusion. Factor the latter two out into their own decl nodes,
with a common abstract base for "type parameters", and push these
nodes throughout the frontend.
No real functionality change, but this is a step toward uniquing
polymorphic types, among other things.
Swift SVN r7345
This separates the concerns of "deserialization the AST structures" from
"reading and accessing a module file".
No functionality change.
Swift SVN r7338
