If we don't have an associated TypeRepr for a
contextual type in the constraint system, dump the
ASTNode that it's for instead.
Before:
```
Contextual Type: $T2
```
After:
```
Contextual Type: $T2 at DeclRef@/Users/hamish/src/swift-test-arena/swift-test-arena/main.swift:1493:21
```
`SyntacticElement` represents a statement, pattern, declaration,
condition, or expression and could originate from i.e. a closure,
a function or a result builder body.
In order to fit with the new IUO model where
functions with IUO results have the disjunction
formed when matching result types, we need to
update this logic to form applicable fn
constraints for the implicit `x[dynamicMember:]`
subscript call.
This is done using a new ImplicitDynamicMemberSubscript
locator path element to allow easy identification of
what the right callee and argument list should be.
Use this new element to represent the overload type
for a constructor call, and have it store a bit
indicating whether the call is for a short-form
`X(...)` or self-delegating `self.init(...)` call.
* [TypeResolver][TypeChecker] Add support for structural opaque result types
* [TypeResolver][TypeChecker] Clean up changes that add structural opaque result types
One can convert from a function value without a global actor to a
similar function type that does have a global actor, but one cannot
remove or change a global actor on a function type.
New name is `isInKeyPathComponent` since it's implemeneted as a
check for presence of `KeyPathComponent` element in the locator
that covers every sub-element contained in a key path component
as well.
Introduce `@concurrent` attribute on function types, including:
* Parsing as a type attribute
* (De-/re-/)mangling for concurrent function types
* Implicit conversion from @concurrent to non-@concurrent
- (De-)serialization for concurrent function types
- AST printing and dumping support
Records protocol requirement associated with a particular type in
the constraint system, also useful to track parent conformance
for conditional requirements.
It was used for unresolved member and `.dynamicType` references
as well as a couple of other places, but now unresolved member
references no longer need that due to new implicit "chain result"
AST node and other places could use more precise locators
e.g. new `.dynamicType` locator or `sequence element` for `for in`
loops.
`ArgumentAttribute` points to a particular attribute associated
with one of the arguments e.g. `inout` or its type e.g. `@escaping`.
This is very useful when dealing with argument-to-parameter
failures because it allows to express in the locator kind
of a problem.
