unexpectedly found nil while unwrapping an Optional value

[aaroncrespo]

Running the language server:

import Foundation
struct Foo {
  var i = 0
}
struct Bar {
  var k: Foo

  func test() {
      k.
       _^_
  }
}

fatal error: unexpectedly found nil while unwrapping an Optional value
Current stack trace:
0    libswiftCore.dylib                 0x000000010205cce0 swift_reportError + 132
1    libswiftCore.dylib                 0x000000010207a090 _swift_stdlib_reportFatalError + 61
2    libswiftCore.dylib                 0x0000000101e700c0 specialized specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) -> A) -> A + 355
3    libswiftCore.dylib                 0x0000000101fec230 partial apply for (_fatalErrorMessage(StaticString, StaticString, StaticString, UInt, flags : UInt32) -> Never).(closure #2) + 109
4    libswiftCore.dylib                 0x0000000101e700c0 specialized specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) -> A) -> A + 355
5    libswiftCore.dylib                 0x0000000101fa43f0 specialized _fatalErrorMessage(StaticString, StaticString, StaticString, UInt, flags : UInt32) -> Never + 96
6    LanguageServer                     0x0000000101873e70 handle(Request) -> Response + 2030
7    LanguageServer                     0x0000000101871950 (closure #1) + 2132
8    LanguageServer                     0x00000001018733f0 thunk + 73
9    Foundation                         0x00007fff82232bfe -[__NSObserver _doit:] + 304
10   CoreFoundation                     0x00007fff80806a60 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12
11   CoreFoundation                     0x00007fff808067c0 _CFXRegistrationPost + 427
12   CoreFoundation                     0x00007fff808066a0 ___CFXNotificationPost_block_invoke + 50
13   CoreFoundation                     0x00007fff807c3640 -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1827
14   CoreFoundation                     0x00007fff807c2b40 _CFXNotificationPost + 604
15   Foundation                         0x00007fff821e99f5 -[NSNotificationCenter postNotificationName:object:userInfo:] + 66
16   Foundation                         0x00007fff822a6a7c _performFileHandleSource + 1144
17   CoreFoundation                     0x00007fff80810970 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
18   CoreFoundation                     0x00007fff807f1850 __CFRunLoopDoSources0 + 557
19   CoreFoundation                     0x00007fff807f0bd0 __CFRunLoopRun + 934
20   CoreFoundation                     0x00007fff807f07d0 CFRunLoopRunSpecific + 420
21   Foundation                         0x00007fff822054fd -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 277
22   Foundation                         0x00007fff8220549e -[NSRunLoop(NSRunLoop) run] + 76
23   LanguageServer                     0x00000001018713d0 main + 1035
24   libdyld.dylib                      0x00007fff95d59254 start + 1
[Info  - 3:56:26 PM] Connection to server got closed. Server will restart.

[RLovelett]

This is one of those things I've got to do: remove all the IUOs.

While I try and replicate this locally and test. I thought I might share this. It might help you come up with a fix for the issue while I try and work it from my end.

Thanks for the report @aaroncrespo!

[RLovelett]

Still working on this. I've at least narrowed this down to what it should be directly from SourceKit. This is the expected desired input and output.

{
    key.request: source.request.codecomplete,
    key.sourcetext: "import Foundation\nstruct Foo {\n  var i = 0\n}\nstruct Bar {\n  var k: Foo\n\n  func test() {\n      k.\n  }\n}\n",
    key.offset: 96,
    key.compilerargs: ["<input>"]
}

{
  key.results: [
    {
      key.kind: source.lang.swift.decl.var.instance,
      key.name: "i",
      key.sourcetext: "i",
      key.description: "i",
      key.typename: "Int",
      key.context: source.codecompletion.context.thisclass,
      key.num_bytes_to_erase: 0,
      key.associated_usrs: "s:vV4main3Foo1iSi",
      key.modulename: "main"
    }
  ]
}

[RLovelett]

@aaroncrespo I'm going to call this one done because I can no longer replicate it locally.

I'm not entirely sure which one of the recent two commits, 9ef2278 or fea20f5, did it but my guess is 9ef2278.

Either way I've added a bunch of new logging on macOS 10.12 for the unified logging system. Hopefully if you do experience this again it'll help you to provide me with more clues.

Please re-open if you can still replicate it on master.