stdlib: fix availability for internal COW checks.

[eeckstein]

Those checks should only be done if linked with a built library, but not when linked with the OS libraries.

Also: disable COW checking by default, and enable it for specific tests
COW checking needs that all libraries are consistently compiled with asserts enabled. This is not the case for the Foundation overlay anymore.
Therefore it does not work with some tests which interop with Foundation.
The solution here is to disable COW checking by default, but enable it for Array tests which do not interop with Foundation.

rdar://79412058

[eeckstein]

@swift-ci smoke test

[eeckstein]

@swift-ci smoke test

[benrimmington]

Could you add a -Xfrontend -define-availability macro to a CMake file?

EDIT: And somehow protect the 9999 versions from accidental Find & Replace?

if(enable_assertions)
  # "9999" means: enable if linked with a built library,
  # but not when linked with the OS libraries.
  # Note: this must not be changed to a "real" OS version.
  set(v9999 9999)
  list(APPEND swift_stdlib_compile_flags "-Xfrontend" "-define-availability")
  list(APPEND swift_stdlib_compile_flags "-Xfrontend" "\"SwiftStdlib_InternalCOWChecks:macOS ${v9999}, iOS ${v9999}, watchOS ${v9999}, tvOS ${v9999}\"")
endif()

@available(SwiftStdlib_InternalCOWChecks, *)

if #available(SwiftStdlib_InternalCOWChecks, *) {

[eeckstein]

@swift-ci test

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - f8849a0e1cc068016ced409d4be144dab1cba6ac

[varungandhi-apple]

Tracking radar: rdar://79412058 (Fix availability for internal COW checks)

[eeckstein]

@benrimmington That's an excellent idea! Unfortunately there are some problems when this goes through a swift interface file: https://ci.swift.org/job/swift-PR-macos/27765/console

[benrimmington]

Why are the failures only for watchOS simulator?

Swift.swiftmodule/i386-apple-watchos-simulator.swiftinterface:6029:39: error: expected version number
      if #available(_InternalCOWChecks, *) {
                                      ^

You could try adding a version number to the macro name:

-list(APPEND swift_stdlib_compile_flags "-Xfrontend" "_InternalCOWChecks:macOS ${v9999}, iOS ${v9999}, watchOS ${v9999}, tvOS ${v9999}")
+list(APPEND swift_stdlib_compile_flags "-Xfrontend" "_InternalCOWChecks 1:macOS ${v9999}, iOS ${v9999}, watchOS ${v9999}, tvOS ${v9999}")

-@available(_InternalCOWChecks, *)
+@available(_InternalCOWChecks 1, *)

-if #available(_InternalCOWChecks, *) {
+if #available(_InternalCOWChecks 1, *) {

EDIT: Changed the macro name to use version 1.

[eeckstein]

Adding a version number does not help. The problem is that as soon as it goes through a swiftinterface file, the availability macro is missing. It would be required to add the macro to all swift compiler invocations.

Why are the failures only for watchOS simulator?

I think it depends on the installed Xcode what module files need to be rebuilt for which platform.

[benrimmington]

Adding a version number does not help.

The new Concurrency module uses a similar SwiftStdlib 5.5 macro, without this issue AFAIK.

The problem is that as soon as it goes through a swiftinterface file, the availability macro is missing.

The macro shouldn't be required by swiftinterface files, according to the #33439 description:

The use of availability macros in the @available specification is expanded at parsing and should not be visible in any compiler outputs. This includes the swiftinterfaces which will show the full classic availability specification.

[eeckstein]

ok, seems to be a problem with generating swiftinterface files. I'll let this up to someone else to investigate and fix.

Let's land this change to unblock CI. We can do the fine tuning later.

[eeckstein]

@swift-ci test

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 9a68c5fb4bb526f9aa08fdebbcb4481fd8dd3fe5

[eeckstein]

@swift-ci test macOS

[eeckstein]

@swift-ci test macOS

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 9a68c5fb4bb526f9aa08fdebbcb4481fd8dd3fe5

[eeckstein]

@swift-ci test macOS

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 9a68c5fb4bb526f9aa08fdebbcb4481fd8dd3fe5

[eeckstein]

@swift-ci smoke test

[kavon]

@swift-ci please smoke test macOS platform