[SR-9744] Swift 4.2.1: runtime crash on swift_dynamicCastMetatypeImpl

[swift-ci]

Previous ID	SR-9744
Radar	rdar://problem/47550832
Original Reporter	broadway_lamb (JIRA User)
Type	Bug

Environment

Ubuntu 16.04

Swift version 4.2.1 (swift-4.2.1-RELEASE)

Target: x86_64-unknown-linux-gnu

Additional Detail from JIRA

Votes	0
Component/s	Compiler, Standard Library
Labels	Bug, RunTimeCrash
Assignee	None
Priority	Medium

md5: a45a97a62d8c0db772a41323be90935d

Issue Description:

I'm experiencing a runtime crash on Ubuntu when executing tests for this SPM project https://github.com/broadwaylamb/DependencyFetcher/tree/03e329d5aeeec928546e055a9ea08cd7a4e74c24 on Ubuntu:

* thread #​1, name = 'DependencyFetch', stop reason = signal SIGSEGV: invalid address (fault address: 0x30)
  * frame #&#8203;0: 0x00007ffff765b164 libswiftCore.so`swift_dynamicCastMetatypeImpl(swift::TargetMetadata<swift::InProcess> const*, swift::TargetMetadata<swift::InProcess> const*) + 4
    frame #&#8203;1: 0x00007ffff740acaa libswiftCore.so`swift_swiftValueConformsTo + 74
    frame #&#8203;2: 0x00007ffff765bc25 libswiftCore.so`_dynamicCastToExistential(swift::OpaqueValue*, swift::OpaqueValue*, swift::TargetMetadata<swift::InProcess> const*, swift::TargetExistentialTypeMetadata<swift::InProcess> const*, swift::DynamicCastFlags) + 565
    frame #&#8203;3: 0x00007ffff765b43d libswiftCore.so`checkDynamicCastFromOptional(swift::OpaqueValue*, swift::OpaqueValue*, swift::TargetMetadata<swift::InProcess> const*, swift::TargetMetadata<swift::InProcess> const*, swift::DynamicCastFlags) + 93
    frame #&#8203;4: 0x00007ffff765a00f libswiftCore.so`swift_dynamicCastImpl(swift::OpaqueValue*, swift::OpaqueValue*, swift::TargetMetadata<swift::InProcess> const*, swift::TargetMetadata<swift::InProcess> const*, swift::DynamicCastFlags) + 31
    frame #&#8203;5: 0x00005555555610b2 DependencyFetcherPackageTests.xctest`closure #&#8203;1 in Fetcher.fetch<A>(self=0x0000604000002610, serviceID=(_value = 0x0000603000002e30 -> 0x00007ffff77a48f8 libswiftCore.so`InitialAllocationPool + 15712), service=(makeService = 0x007ffff77a48f872)) at Fetcher.swift:95
    frame #&#8203;6: 0x0000555555561c65 DependencyFetcherPackageTests.xctest`partial apply for closure #&#8203;1 in Fetcher.fetch<A>(_:) at <compiler-generated>:0
    frame #&#8203;7: 0x00007ffff7fa2ca1 libdispatch.so`partial apply forwarder for reabstraction thunk helper <A> from @callee_guaranteed () -> (@out A, @error @owned Swift.Error) to @escaping @callee_guaranteed () -> (@out A, @error @owned Swift.Error) + 17
    frame #&#8203;8: 0x00007ffff7f9b122 libdispatch.so`closure #&#8203;1 () -> () in closure #&#8203;1 (() throws -> A) -> () in Dispatch.DispatchQueue.(_syncHelper in _F417D752D2C4E9330E1C700411CE0C6A)<A>(fn: (() -> ()) -> (), execute: () throws -> A, rescue: (Swift.Error) throws -> A) throws -> A + 82
    frame #&#8203;9: 0x00007ffff7fa2d0d libdispatch.so`merged partial apply forwarder for closure #&#8203;1 () -> () in Dispatch.DispatchQueue.(_syncHelper in _F417D752D2C4E9330E1C700411CE0C6A)<A>(fn: (Dispatch.DispatchWorkItem) -> (), flags: Dispatch.DispatchWorkItemFlags, execute: () throws -> A, rescue: (Swift.Error) throws -> A) throws -> A + 29
    frame #&#8203;10: 0x00007ffff7fa2ce0 libdispatch.so`partial apply forwarder for closure #&#8203;1 () -> () in closure #&#8203;1 (() throws -> A) -> () in Dispatch.DispatchQueue.(_syncHelper in _F417D752D2C4E9330E1C700411CE0C6A)<A>(fn: (() -> ()) -> (), execute: () throws -> A, rescue: (Swift.Error) throws -> A) throws -> A + 16
    frame #&#8203;11: 0x00007ffff7fa0131 libdispatch.so`partial apply forwarder for reabstraction thunk helper from @callee_guaranteed () -> () to @escaping @callee_guaranteed () -> () + 17
    frame #&#8203;12: 0x00007ffff7f93c0e libdispatch.so`reabstraction thunk helper from @escaping @callee_guaranteed () -> () to @callee_unowned @convention(block) () -> () + 14
    frame #&#8203;13: 0x00007ffff7fb206f libdispatch.so`_dispatch_queue_barrier_sync_invoke_and_complete + 95
    frame #&#8203;14: 0x00007ffff7f9d53e libdispatch.so`Dispatch.DispatchQueue.sync(execute: () -> ()) -> () + 158
    frame #&#8203;15: 0x00007ffff7f9fa81 libdispatch.so`partial apply forwarder + 17
    frame #&#8203;16: 0x00007ffff7f9afcb libdispatch.so`Dispatch.DispatchQueue.(_syncHelper in _F417D752D2C4E9330E1C700411CE0C6A)<A>(fn: (() -> ()) -> (), execute: () throws -> A, rescue: (Swift.Error) throws -> A) throws -> A + 267
    frame #&#8203;17: 0x00007ffff7f9b48e libdispatch.so`Dispatch.DispatchQueue.sync<A>(execute: () throws -> A) throws -> A + 174
    frame #&#8203;18: 0x00005555555604fe DependencyFetcherPackageTests.xctest`Fetcher.fetch<A>(service=(makeService = 0x007ffff77a48f872), self=0x0000604000002610) at Fetcher.swift:94
    frame #&#8203;19: 0x00005555555653d4 DependencyFetcherPackageTests.xctest`FetcherTests.testDefaultFetcher(self=0x00006070000003a0) at FetcherTests.swift:24
    frame #&#8203;20: 0x0000555555568bb9 DependencyFetcherPackageTests.xctest`partial apply for FetcherTests.testDefaultFetcher() at <compiler-generated>:0
    frame #&#8203;21: 0x0000555555565bdc DependencyFetcherPackageTests.xctest`thunk for @escaping @callee_guaranteed () -> () at <compiler-generated>:0
    frame #&#8203;22: 0x0000555555568ba1 DependencyFetcherPackageTests.xctest`partial apply for thunk for @escaping @callee_guaranteed () -> () at <compiler-generated>:0
    frame #&#8203;23: 0x00007ffff7efce71 libXCTest.so`partial apply forwarder for reabstraction thunk helper from @escaping @callee_guaranteed (@in_guaranteed ()) -> (@out ()) to @escaping @callee_guaranteed () -> () + 17
    frame #&#8203;24: 0x00007ffff7efcecc libXCTest.so`partial apply forwarder for closure #&#8203;1 (XCTest.XCTestCase) throws -> () in XCTest.(test in _3BE257A46ADB477C7BF2D39968B39F9D)<A where A: XCTest.XCTestCase>((A) -> () throws -> ()) -> (XCTest.XCTestCase) throws -> () + 76
    frame #&#8203;25: 0x00007ffff7efce54 libXCTest.so`partial apply forwarder for reabstraction thunk helper from @escaping @callee_guaranteed (@guaranteed XCTest.XCTestCase) -> (@error @owned Swift.Error) to @escaping @callee_guaranteed (@in_guaranteed XCTest.XCTestCase) -> (@out (), @error @owned Swift.Error) + 20
    frame #&#8203;26: 0x00007ffff7efd377 libXCTest.so`partial apply forwarder for reabstraction thunk helper from @escaping @callee_guaranteed (@in_guaranteed XCTest.XCTestCase) -> (@out (), @error @owned Swift.Error) to @escaping @callee_guaranteed (@guaranteed XCTest.XCTestCase) -> (@error @owned Swift.Error) + 39
    frame #&#8203;27: 0x00007ffff7ee9c88 libXCTest.so`XCTest.XCTestCase.invokeTest() -> () + 72
    frame #&#8203;28: 0x00007ffff7ee990a libXCTest.so`XCTest.XCTestCase.perform(XCTest.XCTestRun) -> () + 314
    frame #&#8203;29: 0x00007ffff7ee1930 libXCTest.so`XCTest.XCTest.run() -> () + 640
    frame #&#8203;30: 0x00007ffff7ee0cee libXCTest.so`XCTest.XCTestSuite.perform(XCTest.XCTestRun) -> () + 654
    frame #&#8203;31: 0x00007ffff7ee1210 libXCTest.so`XCTest.XCTestSuite.perform(XCTest.XCTestRun) -> () + 1968
    frame #&#8203;32: 0x00007ffff7ee1016 libXCTest.so`XCTest.XCTestSuite.perform(XCTest.XCTestRun) -> () + 1462
    frame #&#8203;33: 0x00007ffff7ee8c18 libXCTest.so`XCTest.XCTMain(Swift.Array<(testCaseClass: XCTest.XCTestCase.Type, allTests: Swift.Array<(Swift.String, (XCTest.XCTestCase) throws -> ())>)>) -> Swift.Never + 3960
    frame #&#8203;34: 0x00005555555648e1 DependencyFetcherPackageTests.xctest`main at LinuxMain.swift:17
    frame #&#8203;35: 0x00007ffff5b85830 libc.so.6`__libc_start_main(main=(DependencyFetcherPackageTests.xctest`main at LinuxMain.swift), argc=1, argv=0x00007fffffffe3b8, init=<unavailable>, fini=<unavailable>, rtld_fini=<unavailable>, stack_end=0x00007fffffffe3a8) at libc-start.c:291

Here's the code where the crash occurs:

  public func fetch<T>(_ service: Service<T>) -> T {
    let serviceID = ObjectIdentifier(service)
    return _syncQueue.sync {
      if let service = _instances[serviceID] as? T { // CRASH
        return service
      } else {
        let instance = _overrides[serviceID]?() as? T ?? service.makeService() // CRASH
        _instances[serviceID] = instance
        return instance
      }
    }
  }

The crash occurs only when running `swift test` for the package. When the package is added as a dependency for an executable with the same code as in the testing method, everything is fine.

This code works fine though:

  public func fetch<T>(_ service: Service<T>) -> T {
    let serviceID = ObjectIdentifier(service)
    return _syncQueue.sync {
      let instance = _instances[serviceID]
      if instance != nil, let instance = instance as? T {
        return instance
      } else {
        let overridenMakeService = _overrides[serviceID]
        let result: T
        if overridenMakeService != nil,
          let inst = overridenMakeService!() as? T {
          result = inst
        } else {
          result = service.makeService()
        }
        _instances[serviceID] = result
        return result
      }
    }
  }

Unfortunately, I wasn't able to reduce the test case.