As part of the code completion redesign this new entry point is going
to replace use of:
- `typeCheckExpression`
- `getTypeOfExpressionWithoutApplying` (which could be removed)
and possibly other methods currently used to retrieve information
for code completion purposes.
Advantages of a new approach:
- Avoids mutating AST;
- Allows to avoid sub-expression type-checking;
- Allows code completion access to multiple solutions in ambiguous cases;
- Provides all possible solutions - valid and invalid (with holes);
- Allows code completion to easily access not only types but
overload choices and other supplimentary information associated
with each solution.
Introduce an experimental mode (behind the flag
`experimental-one-way-closure-params`) that places one-way
constraints between closure parameter types and references to those
parameters within the body of the closure. The intent here is to
break up constraint systems further, potentially improving type
checking performance and making way for larger closure bodies to be
supported.
This is a source-breaking change when the body of a single-expression
closure is used to determine the parameter types. One obvious example
is when there is no contextual type, e.g.,
let _ = { $0 + 1 }
this type-checks today because `1` becomes `Int`, which matches the
`+` overload with the type `(Int, Int) -> Int`, determining the
parameter type `Int` for the closure. Such code would not type-check
with one-way constraints.
Now that these are stored in the TypeResolution object itself, and all callers that mutate flags create a new resolution object, this data can be derived from the resolution itself.
Add the appropriate assertions to ensure that the now-redundant options parameters are being kept in sync so they can be retracted.
The eventual goal is to have TypeResolution requestified.
All callers can trivially be refactored to use ModuleDecl::lookupConformance()
instead. Since this was the last flag in ConformanceCheckOptions, we can remove
that, too.
Rename `addNewFailingConstraint` to
`recordFailedConstraint`, and call into it
whenever a constraint fails, instead of setting
`failedConstraint`. This ensures that
`-debug-constraints` will always log the constraint
that failed a given scope.
In addition, introduce `retireFailedConstraint`
to cover the common case of retiring a constraint
that just failed.
Currently `simplifyAppliedOverloads` depends on
the order in which constraints are simplified,
specifically that a lookup constraint for a
function gets simplified before the applicable
function constraint. This happens to work out
just fine today with the order in which we
re-activate constraints, but I'm planning on
changing that order.
This commit changes the logic such that it it's no
longer affected by the order in which constraints
are simplified. We'll now run it when either an
applicable function constraint is added, or a new
bind overload disjunction is added. This also
means we no longer need to run it potentially
multiple times when simplifying the applicable fn.
This is a follow up to changes related to contextual availability
(https://github.com/apple/swift/pull/29921) which increased score
for unavailable declarations only if they were overloaded but
overlooked a case of a single unavailable choice.
Resolve: rdar://problem/60047439
Implement support for switch statements within function builders. Cases can
perform arbitrary pattern matches, e.g.,
tuplify(true) { c in
"testSwitchCombined"
switch e {
case .a:
"a"
case .b(let i, _?), .b(let i, nil):
i + 17
}
}
subject to the normal rules of switch statements. Cases within function
builders cannot, however, include “fallthrough” statements, because those
(like “break” and “continue”) are control flow.
The translation of performed for `switch` statements is similar to that of
`if` statements, using `buildEither(first:)` and `buildEither(second:)` on
the function builder type.
This is the bulk of switch support, tracked by rdar://problem/50426203.
