Introsuce a new "forward" algorithm for trailing closures where
the unlabeled trailing closure argument matches the next parameter in
the parameter list that can accept an unlabeled trailing closure.
The "can accept an unlabeled trailing closure" criteria looks at the
parameter itself. The parameter accepts an unlabeled trailing closure
if all of the following are true:
* The parameter is not 'inout'
* The adjusted type of the parameter (defined below) is a function type
The adjusted type of the parameter is the parameter's type as
declared, after performing two adjustments:
* If the parameter is an @autoclosure, use the result type of the
parameter's declared (function) type, before performing the second
adjustment.
* Remove all outer "optional" types.
For example, the following function illustrates both adjustments to
determine that the parameter "body" accepts an unlabeled trailing
closure:
func doSomething(body: @autoclosure () -> (((Int) -> String)?))
This is a source-breaking change. However, there is a "fuzzy" matching
rule that that addresses the source break we've observed in practice,
where a defaulted closure parameter precedes a non-defaulted closure
parameter:
func doSomethingElse(
onError: ((Error) -> Void)? = nil,
onCompletion: (Int) -> Void
) { }
doSomethingElse { x in
print(x)
}
With the existing "backward" scan rule, the trailing closure matches
onCompletion, and onError is given the default of "nil". With the
forward scanning rule, the trailing closure matches onError, and there
is no "onCompletion" argument, so the call fails.
The fuzzy matching rule proceeds as follows:
* if the call has a single, unlabeled trailing closure argument, and
* the parameter that would match the unlabeled trailing closure
argument has a default, and
* there are parameters *after* that parameter that require an argument
(i.e., they are not variadic and do not have a default argument)
then the forward scan skips this parameter and considers the next
parameter that could accept the unlabeled trailing closure.
Note that APIs like doSomethingElse(onError:onCompletion:) above
should probably be reworked to put the defaulted parameters at the
end, which works better with the forward scan and with multiple
trailing closures:
func doSomethingElseBetter(
onCompletion: (Int) -> Void,
onError: ((Error) -> Void)? = nil
) { }
doSomethingElseBetter { x in
print(x)
}
doSomethingElseBetter { x in
print(x)
} onError: { error in
throw error
}
After the TypeLocs were removed here, the TypeRepr from the IsExpr was
the only thing providing access to syntactic information from the parent
IsExpr. In order to support this, it was possible to construct a bizarre
ConditionalCheckedCastExpr that contained both semantic and syntactic
information. This doesn't comport with the rest of the casting nodes,
which force you to pick one or the other.
Since we're rewriting an IsExpr into a EnumIsCaseExpr, let's just stash
the syntactic information there. This unblocks a bit of cleanup.
Detect that result type of the overload choice is l-value and preserve
that information through the forced unwrap operation so it's possible
to load the value implicitly during solution application.
Resolves: rdar://problem/61337704
Extracts the list of magic identifier literal kinds into a separate file and updates a lot of code to use macro metaprogramming instead of naming half a dozen cases manually. This is a complicated change, but it should be NFC.
Instead of special casing argument-to-parameter matching for
object literal expressions, let's allow constraint system to
lookup a witness initializer and apply it to the given set
of arguments.
This also simplifies constraint application because
`coerceCallArguments` could be used to form type-checked
argument expression.
AST rewriter needs to make sure that all of the arguments are loaded
since it's currently possible to pass l-value type as an argument to
object literal (`#{file, color, image}Literal`).
Resolves: rdar://problem/62927467
Generalize the code used to generate constraints and apply solutions to
PatternBindingDecls so that it is handled directly by the constaint
system and solution, respectively, rather than as part of the function
builder transform. No functionality change, but this is a cleaner
abstraction.
Single-expression closures have always been traversed differently
from multi-statement closures. The former were traversed as if the
expression was their only child, skipping the BraceStmt and implicit
return, while the later was traversed as a normal BraceStmt.
Unify on the latter treatment, so that traversal
There are a few places where we unintentionally relied on this
expression-as-child behavior. Clean those up to work with arbitrary
closures, which is an overall simplification in the logic.
Introduce a new predicate, shouldTypeCheckInEnclosingExpression(), to
determine when the body of a closure should be checked as part of the
enclosing expression rather than separately, and use it in the various
places where "hasSingleExpressionBody()" was used for that purpose.
Slim down CSApply.cpp by moving the logic for applying a solution to a
closure into CSClosure.cpp. Also, eliminate duplicated logic for applying
function builders to the body of a closure or function. This should
not change semantics at all.
Re-implement operator and precedencegroup decl
lookup to use `namelookup::getAllImports` and
existing decl shadowing logic. This allows us to
find operator decls through `@_exported` imports,
prefer operator decls defined in the same module
over imported decls, and fixes a couple of other
subtle issues.
Because this new implementation is technically
source breaking, as we can find multiple results
where we used to only find one result, it's placed
behind the new Frontend flag
`-enable-new-operator-lookup` (with the aim of
enabling it by default when we get a new language
mode).
However the new logic will always be used if the
result is unambiguous. This means that e.g
`@_exported` operators will be instantly available
as long as there's only one candidate. If multiple
candidates are found, we fall back to the old
logic.
Resolves SR-12132.
Resolves rdar://59198796.
Annotate the covered switches with `llvm_unreachable` to avoid the MSVC
warning which does not recognise the covered switches. This allows us
to avoid a spew of warnings.
that allows arbitrary `label: {}` suffixes after an initial
unlabeled closure.
Type-checking is not yet correct, as well as code-completion
and other kinds of tooling.
Accept trailing closures in following form:
```swift
foo {
<label-1>: { ... }
<label-2>: { ... }
...
<label-N>: { ... }
}
```
Consider each labeled block to be a regular argument to a call or subscript,
so the result of parser looks like this:
```swift
foo(<label-1>: { ... }, ..., <label-N>: { ... })
```
Note that in this example parens surrounding parameter list are implicit
and for the cases when they are given by the user e.g.
```swift
foo(bar) {
<label-1>: { ... }
...
}
```
location of `)` is changed to a location of `}` to make sure that call
"covers" all of the transformed arguments and parser result would look
like this:
```swift
foo(bar,
<label-1>: { ... }
)
```
Resolves: rdar://problem/59203764
Also extend returned object from simplify being an expression to
`TrailingClosure` which has a label, label's source location and
associated closure expression.
This is achieved in 3 steps:
1. CSApply detects assignments to property wrappers inside constructors, and produces an `inout` expr instead of a `load`, which it normally would because nonmutating setters take the `self` by-value. This is necessary becasue the assign_by_wrapper instruction expects an address type for its $1 operand.
2. SILGenLValue now emits the assign_by_wrapper pattern for such setters, ignoring the fact that they capture `self` by value. It also introduces an additional load instruction for the setter patrial_apply because the setter signature still expects a value and we now have an address (because of (1)).
3. DefiniteInitialization specifically ignores load instructions used to produce a `self` value for a setter referenced on assign_by_wrapper because it will be deleted by lowering anyway.
Resolves rdar://problem/60600911 and rdar://problem/52280477
All callers can trivially be refactored to use ModuleDecl::lookupConformance()
instead. Since this was the last flag in ConformanceCheckOptions, we can remove
that, too.
Calling TypeChecker::conformsToProtocol() with SkipConditionalRequirements
and an invalid SourceLoc() is now the same as calling
ModuleDecl::lookupConformance(), so we can replace all usages of
TypeChecker::LookUpConformance with LookUpConformanceInModule.
If any arguments were defaulted the tuple/paren was made implicit, even though
the original tuple/paren was present in the source.
This prevented some sourcekit ASTWalkers from considering them, making
refactorings, documentation info, jump-to-definition and other features
unavailable when queried via their argument labels.
Resolves rdar://problem/62118957
Remove duplication in the modeling of TypeExpr. The type of a TypeExpr
node is always a metatype corresponding to the contextual
type of the type it's referencing. For some reason, the instance type
was also stored in this TypeLoc at random points in semantic analysis.
Under the assumption that this instance type is always going to be the
instance type of the contextual type of the expression, introduce
a number of simplifications:
1) Explicit TypeExpr nodes must be created with a TypeRepr node
2) Implicit TypeExpr nodes must be created with a contextual type
3) The typing rules for implicit TypeExpr simply opens this type
