SourceKit-LSP crashes when selecting non-Xcode toolchain on macOS

[twof]

Swift version

swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-22-a

Platform

macOS 15.0 beta

Editor

VS Code

Does the issue reproduce with Swift 6?

Yes

Description

I get an error

EverythingButTheBagelCore/Package.swift: {"code":null,"killed":false,"signal":"SIGSEGV","cmd":"/Library/Developer/Toolchains/swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-22-a.xctoolchain/usr/bin/swift package describe --type json"}

EverythingButTheBagelCore is the name of the package.

Steps to Reproduce

Install noted toolchain, switch to it in VS Code selecting workspace

Logging

% sourcekit-lsp diagnose
sourcekit-lsp diagnose collects information that helps the developers of sourcekit-lsp diagnose and fix issues.
This information contains:
- Crash logs from SourceKit
- Log messages emitted by SourceKit
- Versions of Swift installed on your system
- If possible, a minimized project that caused SourceKit to crash
- If possible, a minimized project that caused the Swift compiler to crash

All information is collected locally.

                                          Diagnosing sourcekit-lsp issues
 0% [-------------------------------------------------------------------------------------------------]
Collecting log messageszsh: segmentation fault  sourcekit-lsp diagnose

It does not appear that anything was generated. Where should it be?

[twof]

Additional output from SourceKit LSP

[Info  - 5:12:33 PM] Connection to server got closed. Server will restart.
true
[Error - 5:12:33 PM] Server process exited with signal SIGSEGV.
[Info  - 5:12:34 PM] Connection to server got closed. Server will restart.
true
[Error - 5:12:34 PM] Server process exited with signal SIGSEGV.
[Info  - 5:12:34 PM] Connection to server got closed. Server will restart.
true
[Error - 5:12:34 PM] Server process exited with signal SIGSEGV.
[Info  - 5:12:35 PM] Connection to server got closed. Server will restart.
true
[Error - 5:12:35 PM] Server process exited with signal SIGSEGV.
[Info  - 5:12:36 PM] Connection to server got closed. Server will restart.
true
[Error - 5:12:36 PM] Server process exited with signal SIGSEGV.
[Error - 5:12:36 PM] Server process exited with signal SIGSEGV.
[Error - 5:12:37 PM] Request textDocument/documentSymbol failed.
Error: Connection is disposed.
	at Lt (/Users/fnord/.vscode/extensions/sswg.swift-lang-1.10.3/dist/extension.js:47:482)
	at Object.sendRequest (/Users/fnord/.vscode/extensions/sswg.swift-lang-1.10.3/dist/extension.js:47:2538)
	at _m.sendRequest (/Users/fnord/.vscode/extensions/sswg.swift-lang-1.10.3/dist/extension.js:55:113948)
	at async u (/Users/fnord/.vscode/extensions/sswg.swift-lang-1.10.3/dist/extension.js:55:55671)
	at async Object.provideDocumentSymbols (/Users/fnord/.vscode/extensions/sswg.swift-lang-1.10.3/dist/extension.js:106:8465)
	at async h.provideDocumentSymbols (/Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:153:98122)
[Error - 5:13:02 PM] Connection to server got closed. Server will not be restarted.

[ahoppen]

Synced to Apple’s issue tracker as rdar://130547854

[twof]

Let me know if I should move this to the VS Code extension repo.

[ahoppen]

This is an issue in SourceKit-LSP (or the Swift toolchains in general), so SourceKit-LSP is the correct repo.

This started crashing sometime between swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-13-a and swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-18-a.

Finishes fine:

/Library/Developer/Toolchains/swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-13-a.xctoolchain/usr/bin/sourcekit-lsp diagnose --components logs

Crashes:

/Library/Developer/Toolchains/swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-18-a.xctoolchain/usr/bin/sourcekit-lsp diagnose --components logs

There were no changes to SourceKit-LSP between these two tags. Both are referring to 7ad1dcf2675abdc2c0a2dec6bbb95ea388f269f5.

The crash is in withCheckedThrowingContinuation. It seems like there was some change in Swift Concurrency that’s causing the crash. I’m checking with them to see if they have an idea.

Thread 1 Crashed:
0   sourcekit-lsp                 	       0x10078d49c specialized withCheckedThrowingContinuation<A>(isolation:function:_:) + 108
1   sourcekit-lsp                 	       0x10078c63d Process.waitUntilExit() + 1
2   sourcekit-lsp                 	       0x1013d4eb5 DiagnoseCommand.addOsLog(toBundle:) + 1
3   sourcekit-lsp                 	       0x1013d929d closure #2 in DiagnoseCommand.run() + 1
4   sourcekit-lsp                 	       0x1013dcaa1 partial apply for closure #2 in DiagnoseCommand.run() + 1
5   sourcekit-lsp                 	       0x1013dc825 specialized DiagnoseCommand.orPrintError(_:) + 1
6   sourcekit-lsp                 	       0x1013d741d DiagnoseCommand.run() + 1
7   sourcekit-lsp                 	       0x1013d9a91 protocol witness for AsyncParsableCommand.run() in conformance DiagnoseCommand + 1
8   sourcekit-lsp                 	       0x10013e371 static AsyncParsableCommand.main() + 1
9   sourcekit-lsp                 	       0x10011cb61 specialized thunk for @escaping @convention(thin) @async () -> () + 1
10  libswift_Concurrency.dylib    	       0x25cef3949 completeTaskAndRelease(swift::AsyncContext*, swift::SwiftError*) + 1

[adam-fowler]

As an aside swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-13-a crashed for me while swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-22-a appears to be working. I do not have the macOS or Xcode betas installed at the moment.

[ahoppen]

swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-13-a was crashing due to #1469, which only affects macOS 14.4 and 14.5.

[ahoppen]

This was caused by swiftlang/swift#74367, the following reduced example crashes on macOS 15.0 beta 2 (24A5279h).

$ cat ./crash.swift 
let _: Int = try await withCheckedThrowingContinuation { continuation in
    continuation.resume(returning: 1)
}
$ /Library/Developer/Toolchains/swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-18-a.xctoolchain/usr/bin/swiftc crash.swift -sdk $(sdk); and ./crash
dyld[73180]: Symbol not found: _$ss31withCheckedThrowingContinuation9isolation8function_xScA_pSgYi_SSyScCyxs5Error_pGXEtYaKlF
  Referenced from: <C6DC9B57-F781-322E-BEEC-7E0F9958E6D3> /Users/alex/Desktop/crash
  Expected in:     <82723C8F-3EEF-354B-B355-CE94DA469AEE> /usr/lib/swift/libswift_Concurrency.dylib
fish: Job 1, './crash' terminated by signal SIGABRT (Abort)

[ahoppen]

The issue here is that the standard library included in macOS 15 beta 2 is incompatible with the standard library contained in swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-18-a – it contains the version of withCheckedContinutation that pre-dates swiftlang/swift#72830, which is ABI-incompatible with the version of withCheckedContinutation included in swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-18-a because it doesn’t contain the isolation parameter. On earlier OSs, the back-deployment checks kick in but here that’s not the case – swiftlang/swift#72830 is marked as being available in SwiftStdlib 6.0, aka macOS 15.0 and macOS 15 beta 2 is … macOS 15.

The best workaround for now is to

• Download swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-13-a
• Clone sourcekit-lsp
• Build sourcekit-lsp using swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-13-a: /Library/Developer/Toolchains/swift-6.0-DEVELOPMENT-SNAPSHOT-2024-06-13-a/usr/bin/swift build
• When using VS Code, point it to the just-built sourcekit-lsp using by adding the following setting in your settings.json: "swift.sourcekit-lsp.serverPath": "/path/to/sourcekit-lsp/.build/arm64-apple-macosx/debug/sourcekit-lsp". Ignore the deprecation warning that VS Code shows.

[ahoppen]

This should be fixed with the release of macOS 15. Note that the Swift open source toolchains are currently experiencing swiftlang/swift#76534 but I’m closing this issue because it has been fixed.