Calls involving single trailing closure arguments require special
handling because we don't have as much contextual information
about function/argument types as in with regular calls, which means
that diagnosing such situations only by `visitApplyExpr`
yields subpar results.
Resolves: SR-4836.
If the contextual closure type expects no parameters but N
parameters where used and all of the them are anonymous, let's
suggest removing them.
Resolves: rdar://problem/32432145
When matching inputs of a function type, be sure to
strip off ParenType sugar so that we don't end up
with ParenTypes in associated type witnesses.
This fixes various issues with SE-0110.
Fixes <rdar://problem/32214649>.
* Give Sequence a top-level Element, constrain Iterator to match
* Remove many instances of Iterator.
* Fixed various hard-coded tests
* XFAIL a few tests that need further investigation
* Change assoc type for arrayLiteralConvertible
* Mop up remaining "better expressed as a where clause" warnings
* Fix UnicodeDecoders prototype test
* Fix UIntBuffer
* Fix hard-coded Element identifier in CSDiag
* Fix up more tests
* Account for flatMap changes
The following code behaves incorrectly due to the presence of this
overload.
let a: Int = 1
let b: Int? = 2
let c: Int? = nil
let result: [Any] = [a, b, c].flatMap { $0 }
Fixes: <rdar://problem/31910642>
Due to implicit promotion to optional it is possible to call flatMap
with a closure, that does not return an optional. This way the code
works, but is unnecessary inefficient. Such uses of flatMap can and
should be replaced with map.
When trying to solve for the test case we attempt to simplify a value
member constraint and it fails because we've bound the LHS type
variable to an optional as a result of other constraints involving
other type variables in the equivalence class of this type
variable.
We don't have enough information to directly deduce the non-optional
type directly from other constraints involving this type variable.
This change results in one interesting type checking anomoly. In Swift
3 mode, we now successfully typecheck an expression that we previously
did not. Although the type checking technically makes sense given the
type checking rules we have in place, it can be a bit surprising to
users. Fortunately we emit a warning that calls out the surprising
behavior of considering an expression unused.
Fixes rdar://problem/30271695.
Previously we would check TMF_UnwrappingOptional flag, which does not
stick with the constraint, so it would not always persist. Now, add a
new OptionalPayload locator element, which is more correct.
Fixes <rdar://problem/30429709>.
`1 { }` was parsed as a call expression with a trailing closure. This made the diagnostics for `var x = 1 { get { ... } }` extremely bad. Resolves SR-3671.
We limit Optional-to-IUO as an implicit conversion to avoid making
common expressions ambiguous. However, this runs into trouble with
function-to-function conversions, which always look for a "Subtype"
relationship for their inputs and outputs. This is a conservative way
for Sema to avoid emitting conversions that SILGen cannot handle.
The problem case here is converting a closure with type '(Any!) ->
Void' to a value of type '(Any?) -> Void':
let f: ((Any?) -> Void) = { (arg: Any!) in }
This is clearly a safe conversion, since 'Any!' and 'Any?' have the
same representation at run time, but historically we've disallowed it
because of the above rules. However, in Swift 3.0 this particular case
was permitted, with the type checker deciding that the 'Any?' argument
to 'f' could first itself be put into an 'Any', then /that/ value
could go through a value-to-optional conversion to make 'Any!'.
Fortunately the emitted code didn't follow this incorrect conversion
path.
This patch doesn't even try to emulate the old behavior. Instead, it
just weakens the restriction on Optional-to-IUO via a new type
matching flag that only applies within the context of matching
function types.
We can consider opening up function conversions in Swift 4 to anything
that supports conversion---not just subtyping---now that SILGen knows
how to automatically reabstract most such things. But whether we do or
not, Optional/IUO is a special case.
https://bugs.swift.org/browse/SR-3758
Convert subtype constraints with inout on one side and type variable
on the other into fixed binding. Constriants like `inout T0 subtype T1`
where (T0 must be materializable) are created when closures are part
of the generic function parameters e.g. `func foo<T>(_ t: T, (inout T) -> Void) {}`
so when such function gets called e.g.
```
var x = 42
foo(x) { $0 = 0 }
```
it's going to try and map closure parameters type (inout T0) - where
is opened generic parameter T - to argument type (T1), which can
be 'inout' but it's uncertain at this stage, but since closure
'declaration' `{ $0 = 0 }` is wrapped inside of a function call,
it has to 'map' parameters to arguments instead of converting them,
see `ConstraintSystem::matchFunctionTypes`.
Resolves: SR-3520, SR-1976, SR-3073, SR-3479.
We have an implicit conversion where a closure with a non-Void
result type can be passed as a function value with a Void
result; this makes single-expression closures more usable in
the case where you want the single expression to be a
statement -- discarding it's result.
Unfortunately we were checking if the locator contains a
ClosureResult component *anywhere* in the path. This is too
permissive. The correct check is that the *last* path component
is a ClosureResult.
Otherwise, we happily convert anything to () *anywhere*
in a closure result, which crashes immediately in SILGen.
Fixes <https://bugs.swift.org/browse/SR-403>.
In Swift 3.0.1, argument labels are ignored when calling a function
having a single parameter of 'Any' type. That is, if we have:
func foo(_: Any) {}
Both of the following were accepted in a no-assert build (an assert
build would crash, but the GM builds of Xcode ship with asserts off):
foo(123)
foo(data: 123)
This behavior was fixed by 578e36a7e1,
but unfortunately we have to revert to the old behavior *and* defeat
the assertion when in Swift 3 mode.
Swift 4 mode still has the correct behavior, where the second call
'foo(data: 123)' produces a diagnostic.
Now, I have to pour myself a strong drink to forget this ever happened.
Fixes <rdar://problem/28952837>.
This reverts commit e172383e2f.
There were two problems with this commit:
- This was a source-breaking change and should have been feature-gated.
- It only addressed one narrow case of SE-0110.
Fixes <rdar://problem/28621719>.
When called with a ParenType wrapping a DependentMemberType,
we would drop the ParenType because we used type->getAs<ParenType>()
rather than dyn_cast<ParenType>(type.getPointer()).
This fixes an existing QoI issue with closure argument tuples,
and prevents another regression once SubstitutedType is removed.
This handles situation when overload for the subscript hasn't been resolved
by constraint solver, such might happen, for example, if solver was allowed to
produce solutions with free or unresolved type variables (e.g. when running diagnostics).
Resolves: <rdar://problem/27329076>, <rdar://problem/28619118>, <rdar://problem/2778734>.
Modify TypeChecker::coerceParameterListToType to always validate and consider only
valid contextual types (contains: no undefined, error, or type variables etc.) for
argument type coercion, such logic prevents erasure of important explicitly specified
type information attached to parameters of the closure expressions being diagnosed.
Resolves: SR-2994.
In the constraint solver, we've traditionally modeled nested type via
a "type member" constraint of the form
$T1 = $T0.NameOfTypeMember
and treated $T1 as a type variable. While the solver did generally try
to avoid attempting bindings for $T1 (it would wait until $T0 was
bound, which solves the constraint), on occasion we would get weird
behavior because the solver did try to bind the type
variable.
With this commit, model nested types via DependentMemberType, the same
way we handle (e.g.) the nested type of a generic type parameter. This
solution maintains more information (e.g., we know specifically which
associated type we're referring to), fits in better with the type
system (we know how to deal with dependent members throughout the type
checker, AST, and so on), and is easier to reason able.
This change is a performance optimization for the type checker for a
few reasons. First, it reduces the number of type variables we need to
deal with significantly (we create half as many type variables while
type checking the standard library), and the solver scales poorly with
the number of type variables because it visits all of the
as-yet-unbound type variables at each solving step. Second, it
eliminates a number of redundant by-name lookups in cases where we
already know which associated type we want.
Overall, this change provides a 25% speedup when type-checking the
standard library.
As an extension of SR-2208 apply contextual conversion failure checking
to all of the expressions diagnosed via FailureDiagnosis::visitApplyExpr.
Resolves <rdar://problem/28909024>.
Always check arguments of the tuple type against corresponding parameters,
otherwise for a single argument functions e.g. foo(_ a: Any) after SE-0046
type checker is going to produce incorrect solution.
From the Swift documentation:
"If you define an optional variable without providing a default value,
the variable is automatically set to nil for you."
- If a parameter type is a sugared function type, mark the type
as non-escaping by default. Previously, we were only doing this
if the parameter type was written as a function type, with no
additional sugar.
This means in the following cases, the function parameter type
is now non-escaping:
func foo(f: ((Int) -> Void))
typealias Fn = (Int) -> Void
func foo(f: Fn)
- Also, allow @escaping to be used in the above cases:
func foo(f: @escaping ((Int) -> Void))
typealias Fn = (Int) -> Void
func foo(f: @escaping Fn)
- Diagnose usages of @escaping in inappropriate locations, instead
of just ignoring them.
It is unfortunate that sometimes we end up desugaring the typealias,
but currently there are other cases where this occurs too, such as
qualified lookpu of protocol typealiases with a concrete base
type, and generic type aliases. A more general representation for
sugared types (such as an AttributedType sugared type) would allow
us to solve this in a more satisfactory manner in the future.
However at the very least this patch factors out the common code
paths and adds comments, so it shouldn't be too bad going forward.
Note that this is a source-breaking change, both because @escaping
might need to be added to parameters with a sugared function type,
and @escaping might be removed if it appears somewhere where we
do not mark function types as non-escaping by default.
