Unify all of the fields of `PotentialBinding` which have to do with
location information into a single field with is either a constraint
(for regular bindings) or constraint locator (for "holes").
This helps to reduce the amount of space used by `PotentialBinding`
as well as propagate more contextual information when binding gets
attempted.
Change the various AST transforms to use prebuilt DeclName constants more heavily rather than an ad-hoc mix of Identifiers, string literals, std::strings, and StringRefs with questionable memory management.
Replaces `ComponentIdentTypeRepr::getIdentifier()` and `getIdLoc()` with `getNameRef()` and `getNameLoc()`, which use `DeclName` and `DeclNameRef` respectively.
This change adds UnresolvedDotExpr::createImplicit() and UnresolvedDeclRefExpr::createImplicit() helpers. These calls simplify several tedious bits of code synthesis that would otherwise become even more tedious with DeclNameRef in the picture.
Now that overload binding for dynamic member
lookup occurs after having recorded the
`subscript(dynamicMember:)` overload, we can
attempt simplification of this constraint right
away.
Rather than adjusting the opened types for choices
referring to `subscript(dynamicMember:)` down to
the result type, only use the result type to
bind the overload type variable. This avoids the
need for a couple of special cases in CSApply.
To facilitate this change, add
`ConstraintSystem::bindOverload`, which deals with
adding the necessary constraints to bind the
overload's type variable. The eventual goal here
is to remove `adjustTypeOfOverloadReference`, with
adjustments to the opened type being moved to
`getTypeOfMemberReference`, and the adding of
constraints being moved to `bindOverloadType`.
The semantic checks for CodingKeys are being duplicated across the value witness synthesis code paths. Just synthesize a CodingKeys enum and let validateCodingKeysEnum do the heavy lifting when we actually need to go emit diagnostics.
CodableConformanceType::TypeNotValidated is unused since the InterfaceTypeRequest changes went through. We can just use the validity of the ProtocolConformanceRef here.
State the previously unstated nested type requirement that CodingKeys adds to the witness requirements of a given type. The goal is to make this member cheap to synthesize, and independent of the expensive protocol conformance checks required to append it to the member list.
Further, this makes a clean conceptual separation between what I'm calling "nested type requirements" and actual type and value requirements.
With luck, we'll never have to use this attribute anywhere else.
The `@derivative(of:)` attribute registers a function as a derivative of another
function. This patch adds the `@derivative(of:)` attribute definition, syntax,
parsing, and printing.
Resolves TF-826.
Todos:
- Type-checking (TF-829).
- Serialization (TF-837).
