Normally, an unbound reference to a generic type within its own context is automatically bound to the identity generic arguments:
```
struct G<T> {
typealias TA = G // as if you wrote G<T>
}
```
Module selectors normally disable this kind of contextual behavior; make sure that this is not an exception.
To pipe the information needed to do this through the constraint solver, we extend FunctionRefInfo to remember whether a module selector was used.
ForEach support for Borrowing sequence
For testing purposes, this commit includes _BorrowingSequence and _BorrowingIterator protocols, with conformance for Span and InlineArray.
Still record overload choices for `makeIterator` and `next` when
solving a `ForEachElement` constraint. This maintains compatibility
with the previous behavior where we would solve these in the constraint
system, since the choices can affect ranking if e.g Collection's
default `makeIterator` is compared with a concrete `makeIterator`
overload. This is a complete hack though and we ought to rip this out
as soon as we can.
rdar://168840696
We no longer need to track the `ForEachStmtInfo` in the
`SyntacticElementTarget`, and we can remove the special diagnostic
logic for `next` and `makeIterator` since those are type-checked
separately now.
Make sure we invalidate when we initially visit the ExprPattern to
ensure that we don't run into issues when generating constraints for
a `where` clause before the constraints for the ExprPattern. We ought
to change the constraint generation there to use a conjunction to
ensure that the pattern is solved before the `where` clause, but I
want to keep this as a quick low risk fix that we can cherry-pick. I'll
switch it to a conjunction in a follow-up.
Make sure we don't produce unnecessary diagnostics while still allowing
things like cursor info to work. No test change since it's covered by
the next commit.
We know this is where the issue is so we can immediately bind to a hole,
ensuring we don't produce unnecessary downstream diagnostics from
things we can't infer.
This works around the fact that existential opening does not currently
work correctly in cases where the argument isn't resolved before the
applicable fn is solved.
Add the application constraint before the member constraint, which
allows us to get rid of the special-cased delaying logic for dynamic
member subscripts. The diagnostic change here is due to the fact that
we no longer have a simplified type for the result in CSGen, which
would also be the case if we had a disjunction for the member.
This never worked correctly and would crash in SILGen, ban the use
of placeholder types. While here, ensure we replace any ErrorTypes
with holes when solving the closure in the constraint system.
Since we can run CSGen multiple times, we need to guard the emission
of the note on whether the TypeRepr was already marked invalid (i.e
whether we already emitted a diagnostic for it).
Previously we would skip type-checking the result expression of a
`return` or the initialization expression of a binding if the contextual
type had an error, but that misses out on useful diagnostics and
prevents code completion and cursor info from working. Change the logic
such that we open ErrorTypes as holes and continue to type-check.
Eagerly bind invalid type references to holes and propagate contextual
type holes in `repairFailures`. This avoids some unnecessary diagnostics
in cases where we have an invalid contextual type.
- Introduce a generic requirements opening function for type resolution,
which is used by the constraint system in cases where we need to
impose requirements on opened type variables.
- Refactor `replaceInferableTypesWithTypeVars` to use this function
when opening generic types that contain either placeholder or unbound
generic types.
Together these changes ensure that we don't drop generic requirements
when an unbound generic or placeholder type is used as a generic
argument.
For a method key path use the locator for the apply itself rather
than the member, ensuring we handle invalid cases where the apply is
the first component, and providing more accurate location info.
