Suppress warnings in synthesized code. The parent decls should already
show a warning.
require_explicit_availability.StructWithImplicitMembers:2:16: warning:
public declarations should have an availability attribute when building
with -require-explicit-availability
public var hashValue: Int { get }
^
Unless you do this, the flag has no effect when used with the driver;
it only worked in conjunction with -Xfrontend.
Noticed while working on <rdar://problem/58490723>.
Add the command line option -require-explicit-availability to detect public
or `@usableFromInline` declarations and warn if they don't declare
an introduction OS version. This option should catch forgotten `@available`
attributes in frameworks where all services are expected to be introduced
by an OS version.
The option -require-explicit-availability-target "macOS 10.14, iOS 12.0"
can be specified for the compiler to suggest fix-its with the missing
attributes `@available(macOS 10.14, iOS 12.0, *)`.
rdar://51001662
