Fix a case where favoring didn't account for "bound" type variable
being wrapped into optional(s) (disjunctions like that are used for
optional conversions). Doing so makes sure that closure result type
is not bound before the body of the closure is "opened", that's
important because body could provide additional context required
to bind result type e.g. `{ $0 as? <Type> }`.
Resolve: rdar://problem/59208419
Delayed constraint generation for the body of the single-statement
closures regressed variadic parameter handling. Fix it by using
`FunctionType::Param::getParameterType` for "internal" version of
the parameter type which translates variadic/inout correctly.
Resolved: rdar://problem/58647769
Instead of trying to hold a "global" set of type variable differences
let's use pair-wise comparison instead because in presence of generic
overloads such would be more precise.
If there are N solutions for a single generic overload we currently
relied on "local" comparison to detect the difference, but it's not
always possible to split the system to do one. Which means higher
level comparisons have to account for "local" (per overload choice)
differences as well otherwise ranking would loose precision.
* WIP implementation
* Cleanup implementation
* Install backedge rather than storing array reference
* Add diagnostics
* Add missing parameter to ResultFinderForTypeContext constructor
* Fix tests for correct fix-it language
* Change to solution without backedge, change lookup behavior
* Improve diagnostics for weak captures and captures under different names
* Remove ghosts of implementations past
* Address review comments
* Reorder member variable initialization
* Fix typos
* Exclude value types from explicit self requirements
* Add tests
* Add implementation for AST lookup
* Add tests
* Begin addressing review comments
* Re-enable AST scope lookup
* Add fixme
* Pull fix-its into a separate function
* Remove capturedSelfContext tracking from type property initializers
* Add const specifiers to arguments
* Address review comments
* Fix string literals
* Refactor implicit self diagnostics
* Add comment
* Remove trailing whitespace
* Add tests for capture list across multiple lines
* Add additional test
* Fix typo
* Remove use of ?: to fix linux build
* Remove second use of ?:
* Rework logic for finding nested self contexts
If return type is a function, it's possible to return a closure
which can have some of its arguments unused in the body e.g.
`let _: () -> ((Int) -> Void) = { return { } }`
In this case resulting closure has to use its only parameter or
explictly ignore it by declaring `_ in`.
Solutions passed to `diagnoseAmbiguityWithFixes` aren't filtered
so we need to remove all of the solutions with the score worse
than overall "best". Also logic has to account for some fixes being
"warnings".
Detect and diagnose a problem when explicitly specified closure
result type doesn't match what is expected by the context:
Example:
```swift
func foo(_: () -> Int) {}
foo { () -> String in "" } // `Int` vs. `String`
```
all cases of missing generic parameters.
In `ComponentStep::take` when there are no bindings or disjunctions, use hole
propagation to default remaining free type variables that aren't for generic
parameters and continue solving. Rather than using a defaultable constraint for
holes, assign a fixed type directly when we have no bindings to try.
If the last parameter is defaulted, there might be
an attempt to use a trailing closure with previous
parameter that accepts a function type e.g.
```swift
func foo(_: () -> Int, _ x: Int = 0) {}
foo { 42 }
```
Resolves: rdar://problem/55102498
Number the parameters starting at 1 in order to
match other diagnostics such as
diag::missing_argument_positional, and change the
text to make it explicit that we're referring to
the parameter position (rather than argument
position).
Introduce a fix/diagnostic when there is a contextual mismatch
between source and destination types of the assignment e.g.:
```swift
var x: Int = 0
x = 4.0 // destination expects an `Int`, but source is a `Double`
```
mismatches in function types.
This improves the diagnostic in cases where we have argument-to-parameter
conversion failures or contextual type mismatches due to inout attribute
mismatches.
This helps us to filter out cases like operator overloads where
`Self` type comes from e.g. default for collection element -
`[1, "hello"].map { $0 + 1 }`. Main problem here is that
collection type couldn't be determined without unification to
`Any` and `+` failing for all numeric overloads is just a consequence.
Introduce a fix to detect and diagnose situations when omitted
generic arguments couldn't be deduced by the solver based on
the enclosing context.
Example:
```swift
struct S<T> {
}
_ = S() // There is not enough context to deduce `T`
```
Resolves: rdar://problem/51203824
Now covers following new areas (alongside simple assignments):
- Contextual type coercions:
- In assignment e.g. `let _: X = foo`
- In return type positions e.g. `func foo() -> A { return bar }`
- Argument-to-parameter applications (including @autoclosure)
Escapingness is a property of the type of a value, not a property of a function
parameter. Having it as a separate parameter flag just meant one more piece of
state that could get out of sync and cause weird problems.
Instead, always look at the noescape bit in a function type as the canonical
source of truth.
This does mean that '@escaping' is now printed in a few diagnostics where it was
not printed before; we can investigate these as separate issues, but it is
correct to print it there because the function types in question are, in fact,
escaping.
Fixes <https://bugs.swift.org/browse/SR-10256>, <rdar://problem/49522774>.
There are cases where SE-0110 allows tuple splatting behavior,
so to aid diagnostics let's use a new type variable to represent
a tuple type formed from existing arguments instead of imploding
them directly.
12a65fffee restricted tuple splat
to a single tuple or type variable parameter, but it has to
support dependent member types as well because they could be
resolved to `Void` (or empty tuple).
Resolves: rdar://problem/48443263
Try to fix constraint system in a way where member
reference is going to be defined in terms of its use,
which makes it seem like parameters match arguments
exactly. Such helps to produce solutions and diagnose
failures related to missing members precisely.
These changes would be further extended to diagnose use
of unavailable members and other structural member failures.
Resolves: rdar://problem/34583132
Resolves: rdar://problem/36989788
Resolved: rdar://problem/39586166
Resolves: rdar://problem/40537782
Resolves: rdar://problem/46211109
