[Typechecker] Fix an issue with @escaping when used with a generic function

[theblixguy]

This PR resolves an issue where using a type alias as an argument to @escaping on a generic function inside a protocol would trigger an error diagnostic. This is a regression in Swift 5.0, which is now fixed.

public protocol FooProtocol {
  typealias CompletionHandler = (Int) -> ()
  func doSomething<T>(with thing: T, then: @escaping CompletionHandler) // ok
}

Resolves SR-9760.
Resolves rdar://problem/47550733

[theblixguy]

cc @xedin

[xedin]

LGTM, +1 on the Slava's remark about comment.

I'll look into refactoring @autoclosure handling a bit here, it has the same problem even after these changes since everything is based on representative.

[xedin]

@swift-ci please test

[xedin]

@swift-ci please test source compatibility

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 24e2966c27b20a367199b4ccf824d7706dca0242

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 24e2966c27b20a367199b4ccf824d7706dca0242

[theblixguy]

@xedin Seems like the both tests are failing (on macOS) due to unrelated issues:

DVTDownloadable: Failed to get authorization with error Error Domain=DVTDownloadableErrors Code=3 "The authorization was denied since no user interaction was possible." UserInfo={AuthorizationErrorCode=-60007, NSLocalizedDescription=The authorization was denied since no user interaction was possible.}
xcodebuild: error: The authorization was denied since no user interaction was possible.

15:16:19 Traceback (most recent call last):
15:16:19 File "./swift-source-compat-suite/run", line 277, in
15:16:19 sys.exit(main())
15:16:19 File "./swift-source-compat-suite/run", line 44, in main
15:16:19 execute_runner(workspace, args)
15:16:19 File "./swift-source-compat-suite/run", line 185, in execute_runner
15:16:19 common.check_execute(runner_command, timeout=9999999)
15:16:19 File "/Users/buildnode/jenkins/workspace/swift-PR-source-compat-suite-debug/swift-source-compat-suite/common.py", line 378, in check_execute
15:16:19 raise ExecuteCommandFailure(command, returncode)
15:16:19 common.ExecuteCommandFailure: ExecuteCommandFailure(command="./runner.py --swiftc /Users/buildnode/jenkins/workspace-private/swift-PR-source-compat-suite-debug/build/compat_macos/install/toolchain/usr/bin/swiftc --projects projects.json --include-actions 'action.startswith("Build")' --swift-branch master --sandbox-profile-xcodebuild ../../../workspace-private/swift-source-compat-suite-sandbox/sandbox_xcodebuild.sb --sandbox-profile-package ../../../workspace-private/swift-source-compat-suite-sandbox/sandbox_package.sb --build-config=debug", returncode=1)

[xedin]

@shahmishal FYI, build failure was:

2019-01-30 12:44:38.176 xcodebuild[23646:2149351]  DVTDownloadable: Failed to get authorization with error Error Domain=DVTDownloadableErrors Code=3 "The authorization was denied since no user interaction was possible." UserInfo={AuthorizationErrorCode=-60007, NSLocalizedDescription=The authorization was denied since no user interaction was possible.}
xcodebuild: error: The authorization was denied since no user interaction was possible.

[xedin]

I also opened a PR to Un-XFAIL GRDB

[xedin]

@swift-ci please test macOS platform

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - be6dc7c

[xedin]

It seems like we'll just have to wait to get this resolved.

[theblixguy]

@xedin oh, okay!

[slavapestov]

@swift-ci Please smoke test macOS

[xedin]

@swift-ci please test source compatibility

[xedin]

@swift-ci please test macOS platform

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - be6dc7c

[theblixguy]

@xedin @slavapestov Source compat is now passing, but macOS test is still failing due to unrelated reason (in test/stdlib/KVOKeyPaths.swift):

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'An instance 0x79673140 of class _TtCC4main7Target25Dummy was deallocated while key value observers were still registered with it. Current observation info: <NSKeyValueObservationInfo 0x796733d0> (
<NSKeyValueObservance 0x796734b0: Observer: 0x79673200, Key path: name, Options: <New: NO, Old: NO, Prior: NO> Context: 0x0, Property: 0x796733b0>

[xedin]

@swift-ci please test macOS platform

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - be6dc7c

[theblixguy]

macOS test still failing because of the same unrelated issue 🤔

[xedin]

@swift-ci please smoke test

[xedin]

maybe smoke test is going to pass...

[theblixguy]

@xedin smoke test has passed 🎉 😅

[xedin]

Looks like the test is failing because of #20103

[theblixguy]

@xedin Ah ok! Since this PR fixed a regression, can this be cherry picked to the 5.0 branch?

[xedin]

@theblixguy Done - #22278