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.
Argument-to-Parameter mismatch handles conformance failures
related to arguments, so the logic in `MissingConformanceFailure`
which wasn't entirely correct is now completely obsolete.
Resolves: rdar://problem/56234611
Currently absence of `subtyping` is the only problem detected and diagnosed specifically
for `inout` parameters, but there could be type mismatches in `inout` positions as well
and we can use `argument-to-parameter mismatch fix to detect and diagnose them.
When it comes to `@autoclosure` parameters we only detect and diagnose
mismatches related to invalid implicit conversions to pointer types. But
`@autoclosure` parameters just like regular ones can have type mismatches
as well which can be handled via recently introduced
`argument-to-parameter mismatch` fix.
This commit changes `getArgumentExprFor` to take
a ConstraintLocator argument from which to find
the argument list. This lets us properly handle
the case where we have a key path subscript
locator. In addition, this commit renames the
member to `getArgumentListExprFor` to make it
clear we're returning the argument list expression
rather than a single argument.
Resolves SR-11562.
This removes all calls to typesSatisfyConstraint() except for the
isConvertibleTo() check at the beginning, in the process making the
analysis a little bit more accurate.
Change `associateArgumentLabels` to take a locator
argument to enable the recording of argument
labels for individual key path components. Then
move the association of argument labels for
subscripts to `addSubscriptConstraints`, and plumb
through the argument labels for key path subscript
components.
This then allows us to correctly ignore choices
with mismatching argument labels while solving in
certain cases.
Resolves SR-11438.
This helps us to better diagnose failures related to generic
requirements like `T == [Int]` as well as protocol compositions,
which require deep equality check.
Since this kind of failure is really a conversion failure, let's
inherit from `Contextual{Mismatch, Failure}` which also helps with
storage for from/to types and their resolution.
Also let's use original types involved in conversion to form
this fix, which helps to perserve all of the original sugar.
Previously in situations like:
```swift
protocol P {}
struct S<T: P> {
var value: T
}
_ = S(value: 42)
```
Diagnostic has reported a problem as related to "reference" to `init`
but the failing generic type requirement belongs to `S`, so a
better diagnostic in such case should mention `generic struct S`.
This way it covers a lot more ground and doesn't conflict with
other fixes.
Another notable change is related to check for IUO associated
with source type, that covers cases like:
```swift
func foo(_ v: NSString!) -> String {
return v
}
```
Instead of general conversion failure check for IUO enables solver
to introduce force downcast fix.
Instead, check them and their error handling right away.
In addition to fixing the crash in the radar, this also causes
us to emit unused variable warnings in functions containing
local functions.
Eventually, TC.definedFunctions should go away altogether.
Fixes <rdar://problem/53956342>.
