Instead of checking for unavailability attributes directly in the solver, which
does not correctly handle members of unavailable extensions, query
`checkDeclarationAvailability()` instead. By using the same underlying logic as
the availability checker the constraint solver can be confident in the accuracy
of this result.
Resolves rdar://87403752.
Instead of checking for unavailability attributes directly in the solver, use `AvailableAttr::isUnavailable` which checks the enclosing extension too, if necessary.
Resolves rdar://92364955
The solver used to check availability attribute on the declaration
itself, a better approach is to go through `AvailableAttr::isUnavailable`
because that also covers unavailable extensions.
Resolves: rdar://92364955
Add a function that deals with invoking syntactic
diagnostics for all the expressions involved in
a SolutionApplicationTarget.
Resolves SR-13260
Resolves rdar://65903005
This is a follow up to changes related to contextual availability
(https://github.com/apple/swift/pull/29921) which increased score
for unavailable declarations only if they were overloaded but
overlooked a case of a single unavailable choice.
Resolve: rdar://problem/60047439
There is a short-circuiting hack in the constraint solver that speeds up
solving, but isn't generally sound. If we allow unavailable decls to be
considered "favored", this can fire and result in our choosing a
solution that involves the unavailable decl where other solutions exist.
Fixes rdar://problem/32570734.
