This wasn't consistently used, and consequently
could result in some expressions getting their
parents invalidated. Instead, replace it with a
query to make sure we don't try and add an
expression we've already computed the parent info
for.
Remove this bit from function decls and closures.
Instead, for closures, infer it from the presence
of a single return or single expression AST node
in the body, which ought to be equivalent, and
automatically takes result builders into
consideration. We can also completely drop this
query from AbstractFunctionDecl, replacing it
instead with a bit on ReturnStmt.
Parse typed throw specifiers as `throws(X)` in every place where there
are effects specified, and record the resulting thrown error type in
the AST except the type system. This includes:
* `FunctionTypeRepr`, for the parsed representation of types
* `AbstractFunctionDecl`, for various function-like declarations
* `ClosureExpr`, for closures
* `ArrowExpr`, for parsing of types within expression context
This also introduces some serialization logic for the thrown error
type of function-like declarations, along with an API to extract the
thrown interface type from one of those declarations, although right
now it will either be `Error` or empty.
Delay constraint generation for capture list until body of
the associated closure is resolved. This means that we can
unify capture checking with that of regular pattern bindings
for multi-statement closures.
Implicit casts are allowed to provide cast type directly without
a type repr, adjust solution application logic to handle this just
like constraint generator does. Also fix a couple of places where
declaration context from constraint system was used instead
of one associated with the expression rewriter.
Implicit casts are allowed to be constructed with a type, instead
of a type repr. Constraint generation should honor that, and fallback
to using cast type when repr is was not given.
