Currently `{inout, array, string}-to-pointer` conversion doesn't
track whether there was a difference in optionality between involved
types which leads to ambiguity when different overload choices
have different optionality requirements.
Let's fix that by increasing a score in cases if pointer type
is itself optional e.g.:
```swift
func foo(_ x: UnsafeMutablePointer<Int>) {}
func foo(_ x: UnsafeMutablePointer<Int>?) {}
foo(&foo) // Should pick the least optional overload choice.
```
Resolves: [SR-8411](https://bugs.swift.org/browse/SR-8411)
All of the argument diagnostics have been ported to the new diagnostic
framework, so now is the time to remove `ArgumentMatcher` and the only
place where it was used - `diagnoseSingleCandidateFailures`.
This commit moves the getNSObjectType and
getObjCSelectorType methods from TypeChecker
onto ASTContext. In addition, it moves the
FOR_KNOWN_FOUNDATION_TYPES macro into a separate
file to define each of the Obj-C type decls
we want to have access to.
If the fix is applied to result type of a function or subscript
invocation increase its impact because such uses are invalid
e.g. assigning a value to a function call `foo() = 42`, or
using read-only subscript as mutating.
```swift
struct S {}
protocol P {}
func foo(_ value: S) {
var p: P? = nil
p = value
}
```
Assignment destination is a protocol `P` and source is a type `S`
which doesn't conform to `P`. Allow solver to detect this situation
and record `ignore assignment destination type` fix which would
cover a single missing conformance as well as protocol composition.
automatically.
This commit also renames `ConstraintSystem::recordHole/isHole` to
`recordPotentialHole` and `isPotentialHole` to make it clear that
we don't know for sure whether a type variable is a hole until it's
bound to unresolved.
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.
This is because we already emit a diagostic to tell the user that the property's type does not match the wrappedValue type, so this diagnostic can be a bit confusing especially because the initializer is synthesized
This commit changes the behaviour of the error for
passing a temporary pointer conversion to an
@_nonEphemeral parameter such that it doesn't
affect overload resolution. This is done by recording
the fix with an impact of zero, meaning that we don't
touch the solution's score.
In addition, this change means we no longer need
to perform the ranking hack where we favour
array-to-pointer, as the disjunction short-circuiting
will continue to happen even with the fix recorded.
Diagnose ephemeral conversions that are passed to @_nonEphemeral
parameters. Currently, this defaults to a warning with a frontend flag
to upgrade to an error. Hopefully this will become an error by default
in a future language version.
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
ProtocolConformanceRef already has an invalid state. Drop all of the
uses of Optional<ProtocolConformanceRef> and just use
ProtocolConformanceRef::forInvalid() to represent it. Mechanically
translate all of the callers and callsites to use this new
representation.
