Swiftlint: Crash introduced in 0.26.0

[johnhammerlund]

New Issue Checklist

• [x] Updated SwiftLint to the latest version
• [x] I searched for existing GitHub issues

There is a similar issue (https://github.com/realm/SwiftLint/issues/2039) but the stack traces seem unrelated

Bug Report

Complete output when running SwiftLint, including the stack trace and command used

$ swiftlint lint
Loading configuration from '.swiftlint.yml'
Linting Swift files in current working directory
Linting 'DarwinNotificationCenter.swift' (1/96)
Linting 'OAuth2Error.swift' (2/96)
Linting 'OAuth2TokenRefreshCoordinator.swift' (3/96)
Linting 'OAuth2TokenDiskStore.swift' (4/96)
...
Linting 'URLSessionClient.swift' (55/96)
Linting 'HTTPRequestBuilder.swift' (56/96)
[1]    53616 illegal hardware instruction  swiftlint

Environment

• SwiftLint version (run swiftlint version to be sure)?
  0.26.0

• Installation method used (Homebrew, CocoaPods, building from source, etc)?
  Homebrew

• Paste your configuration file:

included:
  - Sources
  - Tests

excluded:
  - Sources/Conduit/Auth/Vendor

line_length: 160
statement_position:
  statement_mode: uncuddled_else
type_name:
  min_length: 3
  max_length: 60
identifier_name:
  min_length: 3
  max_length: 60

opt_in_rules:
  - attributes
  - closure_end_indentation
  - closure_spacing 
  - conditional_returns_on_newline
  - empty_count
  - fatal_error_message
  - first_where
  - force_unwrapping
  - joined_default_parameter
  - let_var_whitespace
  - nimble_operator
  - no_extension_access_modifier
  - number_separator
  - object_literal
  - operator_usage_whitespace
  - overridden_super_call
  - pattern_matching_keywords
  - private_outlet
  - prohibited_super_call
  - quick_discouraged_call 
  - redundant_nil_coalescing
  - single_test_class
  - strict_fileprivate
  - switch_case_on_newline
  - trailing_closure
  - unneeded_parentheses_in_closure_argument
  - vertical_parameter_alignment_on_call

Note: This crash still occurs when running swiftlint --enable-all-rules

• Are you using nested configurations?
  If so, paste their relative paths and respective contents.
  No

• Which Xcode version are you using (check xcode-select -p)?
  Xcode 9.4.1, active developer directory is set to /Applications/Xcode.app/Contents/Developer

• Do you have a sample that shows the issue?
  Not yet sure about the exact source of the crash, but this exact failure can be observed here: https://travis-ci.org/mindbody/Conduit

The issue specifically started happening once SwiftLint was updated from 0.25.1 to 0.26.0.

Crash log:

Process:               swiftlint [53483]
Path:                  /usr/local/Cellar/swiftlint/0.26.0/bin/swiftlint
Identifier:            swiftlint
Version:               0
Code Type:             X86-64 (Native)
Parent Process:        zsh [50825]
Responsible:           swiftlint [53483]
User ID:               566097933

Date/Time:             2018-07-02 15:55:20.807 -0700
OS Version:            Mac OS X 10.13.4 (17E202)
Report Version:        12
Anonymous UUID:        77753AA3-F9B6-66B2-C051-8544C46F5487

Sleep/Wake UUID:       FB630A13-637E-437D-A2BE-DDCC8D1AF37B

Time Awake Since Boot: 170000 seconds
Time Since Wake:       25000 seconds

System Integrity Protection: enabled

Crashed Thread:        7  Dispatch queue: com.apple.root.user-initiated-qos

Exception Type:        EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes:       0x0000000000000001, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY

Termination Signal:    Illegal instruction: 4
Termination Reason:    Namespace SIGNAL, Code 0x4
Terminating Process:   exc handler [0]

Thread 7 Crashed:: Dispatch queue: com.apple.root.user-initiated-qos
0   swiftlint                       0x00000001052c4704 NSString.CacheContainer.location(fromByteOffset:) + 468
1   swiftlint                       0x00000001052c3dcd NSString.byteRangeToNSRange(start:length:) + 109
2   swiftlint                       0x000000010546603f specialized NoFallthroughOnlyRule.validate(file:kind:dictionary:) + 143
3   swiftlint                       0x000000010536b251 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA12ForWhereRuleV_Tg5Tm + 433
4   swiftlint                       0x000000010536b2f7 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA21NoFallthroughOnlyRuleV_Tg5 + 23
5   swiftlint                       0x000000010536b167 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA12ForWhereRuleV_Tg5Tm + 199
6   swiftlint                       0x000000010536b2f7 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA21NoFallthroughOnlyRuleV_Tg5 + 23
7   swiftlint                       0x000000010536b167 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA12ForWhereRuleV_Tg5Tm + 199
8   swiftlint                       0x000000010536b2f7 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA21NoFallthroughOnlyRuleV_Tg5 + 23
9   swiftlint                       0x000000010536b167 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA12ForWhereRuleV_Tg5Tm + 199
10  swiftlint                       0x000000010536b2f7 _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_s10DictionaryVySSAK0L16KitRepresentable_pG10dictionarytFAjRcfU_Tf4gnn_nAA21NoFallthroughOnlyRuleV_Tg5 + 23
11  swiftlint                       0x000000010536dcdb _T018SwiftLintFramework7ASTRulePAASS8KindType_8RawValueRTzrlE8validateSayAA14StyleViolationVG012SourceKittenC04FileC4file_tFTf4gn_nAA12ForWhereRuleV_Tg5Tm + 171
12  swiftlint                       0x0000000105368536 protocol witness for Rule.validate(file:) in conformance NoFallthroughOnlyRule + 22
13  swiftlint                       0x0000000105341522 specialized Rule.lint(file:regions:benchmark:superfluousDisableCommandRule:) + 626
14  swiftlint                       0x0000000105348790 partial apply for closure #2 in Linter.getStyleViolations(benchmark:) + 128
15  swiftlint                       0x0000000105348811 _T018SwiftLintFramework4Rule_pAA0B6Result33_5A5F37FCDEE0B4D78BAE05A90BA8A062LLVSgIegio_AaB_pAFIegir_TRTA + 33
16  swiftlint                       0x00000001052e081d specialized closure #1 in closure #1 in Array.parallelMap<A>(transform:) + 93
17  swiftlint                       0x00000001052e7ae9 partial apply for specialized  + 25
18  swiftlint                       0x0000000105609bf7 thunk for @callee_guaranteed (@unowned Int) -> () + 39
19  libdispatch.dylib               0x00007fff6f832221 _dispatch_client_callout2 + 8
20  libdispatch.dylib               0x00007fff6f835d71 _dispatch_apply_serial + 111
21  libdispatch.dylib               0x00007fff6f827e08 _dispatch_client_callout + 8
22  libdispatch.dylib               0x00007fff6f83e019 _dispatch_sync_function_invoke + 54
23  libdispatch.dylib               0x00007fff6f832070 dispatch_apply_f + 947
24  swiftlint                       0x0000000105609b99 static DispatchQueue.concurrentPerform(iterations:execute:) + 217
25  swiftlint                       0x00000001052e05c5 specialized closure #1 in Array.parallelMap<A>(transform:) + 197
26  swiftlint                       0x00000001052e5c88 specialized Array.parallelFlatMap<A>(transform:) + 232
27  swiftlint                       0x000000010533966d Linter.getStyleViolations(benchmark:) + 1485
28  swiftlint                       0x000000010533907d _T018SwiftLintFramework6LinterV15styleViolationsSayAA14StyleViolationVGvg + 13
29  swiftlint                       0x00000001055cdd85 specialized closure #1 in LintCommand.run(_:) + 69
30  swiftlint                       0x00000001055d22fc partial apply for closure #1 in LintCommand.run(_:) + 60
31  swiftlint                       0x00000001055e0ed8 partial apply for closure #2 in closure #2 in closure #2 in Configuration.visitLintableFiles(path:action:useSTDIN:quiet:useScriptInputFiles:forceExclude:cache:parallel:visitorBlock:) + 104
32  swiftlint                       0x00000001055e1599 closure #2 in closure #2 in closure #2 in Configuration.visitLintableFiles(path:action:useSTDIN:quiet:useScriptInputFiles:forceExclude:cache:parallel:visitorBlock:)partial apply + 9
33  swiftlint                       0x00000001055e0f01 partial apply for thunk for @callee_guaranteed () -> (@error @owned Error) + 17
34  swiftlint                       0x00000001055e1569 thunk for @callee_guaranteed () -> (@error @owned Error)partial apply + 9
35  swiftlint                       0x00000001055ea57a autoreleasepool<A>(invoking:) + 58
36  swiftlint                       0x00000001055e12fe specialized closure #2 in closure #2 in Configuration.visitLintableFiles(path:action:useSTDIN:quiet:useScriptInputFiles:forceExclude:cache:parallel:visitorBlock:) + 670
37  swiftlint                       0x00000001055e0c63 partial apply for closure #2 in closure #2 in Configuration.visitLintableFiles(path:action:useSTDIN:quiet:useScriptInputFiles:forceExclude:cache:parallel:visitorBlock:) + 67
38  swiftlint                       0x00000001055d94de closure #4 in closure #2 in Configuration.visitLintableFiles(path:action:useSTDIN:quiet:useScriptInputFiles:forceExclude:cache:parallel:visitorBlock:) + 126
39  swiftlint                       0x00000001055e0f45 partial apply for closure #4 in closure #2 in Configuration.visitLintableFiles(path:action:useSTDIN:quiet:useScriptInputFiles:forceExclude:cache:parallel:visitorBlock:) + 21
40  swiftlint                       0x0000000105609bf7 thunk for @callee_guaranteed (@unowned Int) -> () + 39
41  libdispatch.dylib               0x00007fff6f832221 _dispatch_client_callout2 + 8
42  libdispatch.dylib               0x00007fff6f83215d _dispatch_apply_invoke + 159
43  libdispatch.dylib               0x00007fff6f827e08 _dispatch_client_callout + 8
44  libdispatch.dylib               0x00007fff6f829b7c _dispatch_root_queue_drain + 902
45  libdispatch.dylib               0x00007fff6f8297a5 _dispatch_worker_thread3 + 101
46  libsystem_pthread.dylib         0x00007fff6fb79169 _pthread_wqthread + 1387
47  libsystem_pthread.dylib         0x00007fff6fb78be9 start_wqthread + 13

[eneko]

The problem seems to reside in the SourceKitten framework, ironically caused by a force-unwrap.

SwiftLint 0.26.0 resolves to SourceKitten 0.21.0. Checking the SourceKitten repo, seems like a crash related to Swift 4.2 was fixed on the 0.21.1 release.

SourceKitten 0.21.1 does not seem to be available for SwiftLint (yet), since Yams is locked to 0.20.0.

error: dependency graph is unresolvable; found these conflicting requirements:

Dependencies: 
    https://github.com/jpsim/Yams.git @ 0.7.0..<1.0.0

@jpsim is there an easy way to remove that dependency block to see if 0.21.1 solves this issue?

[eneko]

The file from our project being processed where SwiftLint crashes is this one (has not been updated in the last 7 months):
https://github.com/mindbody/Conduit/blob/master/Sources/Conduit/Networking/URLSessionClientLogging.swift

That file contains a few emoji used for logging purposes, which might be related to the encoding issues causing the crash in SourceKitten.

From the call-stack in Xcode, I believe the rule being validated is "no_fallthrough_only". Within that rule, the crash happens in NoFallthroughOnlyRule.swift, line 170:

public func validate(file: File,
                     kind: StatementKind,
                     dictionary: [String: SourceKitRepresentable]) -> [StyleViolation] {

    guard kind == .case,
        let length = dictionary.length,
        let offset = dictionary.offset,
        case let nsstring = file.contents.bridge(),
        let range = nsstring.byteRangeToNSRange(start: offset, length: length),  // <-- 💥 crash
        let colonLocation = findCaseColon(text: nsstring, range: range)
    else {
        return []
    }

   ...

[SDGGiesbrecht]

It is unlikely that it has anything to do with SourceKitten.

The crash is ultimately due to invalid string index conversions (scalar vs cluster vs byte vs UTF‐16 element).

Far more likely, something in the logic of the no_fallthrough_only rule is mixing them up and then asking SourceKitten to do something out of bounds. (Emoji have some of the largest indexing differences and no_fallthrough_only was added between 0.25.1 and 0.26.0.)

The relevant logic is here, but I could not spot the problem with a quick perusal.

[SDGGiesbrecht]

...but I only see one direct call to byteRangeToNSRange and it uses an unaltered value from SourceKitten, so maybe I’m wrong.

Is the stack trace you provided from an build that was optimized? Are there possibly inlined functions not showing?

[marcelofabri]

I was able to reproduce the problem with this example:

switch code {
    case 200..<300:
        return "\(code) ✅"
    default:
        break

Weirdly, it doesn't happen if I remove the string interpolation.

Also, it looks like the first byteRangeToNSRange call is the one causing the crash, but everything on the rule looks fine up to that point.

[marcelofabri]

I think this is the same issue as https://github.com/jpsim/SourceKitten/issues/444 which was reported on SourceKit as well: https://bugs.swift.org/browse/SR-6443

[SDGGiesbrecht]

Yes, you are right, @marcelofabri.

I did not think of it at first, but now I remember being confused by SourceKit reporting bizarre numbers around interpolation cases—and I was using it directly, not through SourceKitten.

@johnhammerlund, in the meantime disabling no_fallthrough_only ought to avoid triggering the crash.

[johnhammerlund]

Great to know, thanks all for jumping on this so quickly. I'd like to keep that rule enabled, so I'll instead refactor the switch body as a workaround to SR-6443.

[4ndrey]

same for me, and this show-stopper is still not fixed?

[barrault01]

@johnhammerlund, in the meantime disabling no_fallthrough_only ought to avoid triggering the crash.

This solution is really working ☝️ thanks @SDGGiesbrecht

[Statusgman]

Reproduced this bug with this code

enum Foo {
    case one
    case two
}

func bar(foo: Foo) -> String {
    let some = "ru_RU"
    switch foo {
    case .one:
        return "\(some) один"
    default:
        return "\(some) два"
    }
}

disabling no_fallthrough_only rule helps to prevent this crash.

I noticed that removing spaces in return statements will not trigger the crash
return "\(some)два"

PS: reproduced on SwiftLint v 0.28.2 and 0.27

[jpsim]

Thanks for sharing @Statusgman, I was able to reproduce the crash with that example. Fix in https://github.com/jpsim/SourceKitten/pull/570

[jpsim]

Fixed in #2487.

[vigneshnarayanasamy]

This also happens when CommandLines tools for not set in PATH.

[eroth]

This also happens when CommandLines tools for not set in PATH.

Or when xcode-select hasn't been used to select a version of Xcode and CommandLineTools is a command lines instance (https://github.com/realm/SwiftLint/issues/2789#issuecomment-507544839).