sourcekit-lsp crashes repeatedly (diagnose with extended logging attached)

[h12w]

Swift version

swiftlang-6.2.0.19.9

Platform

MacOS 26.0.1

Editor

Cursor 1.7.28, sswg.swift-lang 1.11.4

Description

Installed the Swift extension to Cursor and the LSP keeps crashing.
Tried it on VS Code, same issue.

Steps to Reproduce

No response

Logging

sourcekit-lsp-diagnose-2025-10-02T11-01-34+01-00.zip

[h12w]

Swift › Sourcekit-lsp: Background Indexing
Turns background indexing on or off. auto will enable background indexing if the Swift version is >= 6.1. This option has no effect in Swift versions prior to 6.0.

btw, a workaround is to change this option from "auto" into "off" in Cursor/VS Code. It suppresses the crashing issues and some functionalities seem still there (e.g. hover or click on a symbol to see/goto the definition)

[bnbarham]

Thanks for the diagnose @h12w! Could you try setting backgroundPreparationMode to "noLazy" in your .sourcekit-lsp/config.json? From the crashes this looks like swiftlang/swift#84041, which noLazy should workaround.

[Icodak]

Edit

It appears that this is because I used a macro @Godot(.tool). Whenever i remove it the lsp boots up properly

Original issue

I encounter the same issue on Windows - Swift 6.2-release

Sourcekit Output

2025-10-03 22:11:11.312 [info] [org.swift.sourcekit-lsp:default] default 2025-10-03 20:11:11.3100 +0000
sourcekit-lsp launched from <private>
---
Assertion failed: Loc.Value.getPointer() >= Buffer->getBuffer().begin() && Loc.Value.getPointer() <= Buffer->getBuffer().end() && "Location is not from the specified buffer", file C:\Users\swift-ci\jenkins\workspace\swift-6.2-windows-toolchain\swift\lib\Basic\SourceLoc.cpp, line 341
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	While walking into 'SpinningCube' (at C:\Users\User\Documents\Godot\bee\src\Sources\App\SpinningCube.swift:4:1)
1.	While walking into body of getter for classInitializer (at @__swiftmacro_3App12SpinningCube5GodotfMm_.swift:1:25)
2.	While walking into initializer for declaration 0x13458803a68 (at @__swiftmacro_3App12SpinningCube5GodotfMm_.swift:2:5)
Exception Code: 0x80000003
 #0 0x00007fff110b0565 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x580565)
 #1 0x00007fff9a5f1989 (C:\WINDOWS\System32\ucrtbase.dll+0xc1989)
 #2 0x00007fff9a5d4ab1 (C:\WINDOWS\System32\ucrtbase.dll+0xa4ab1)
 #3 0x00007fff9a5f2986 (C:\WINDOWS\System32\ucrtbase.dll+0xc2986)
 #4 0x00007fff9a5f2b61 (C:\WINDOWS\System32\ucrtbase.dll+0xc2b61)
 #5 0x00007fff166f927a sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x5bc927a)
 #6 0x00007fff10f88cda sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x458cda)
 #7 0x00007fff11de39a6 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x12b39a6)
 #8 0x00007fff11de624e sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x12b624e)
 #9 0x00007fff12af213c sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc213c)
#10 0x00007fff12af6a83 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc6a83)
#11 0x00007fff12af4c6c sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc4c6c)
#12 0x00007fff12af522e sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc522e)
#13 0x00007fff12af28f7 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc28f7)
#14 0x00007fff12af5850 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc5850)
#15 0x00007fff12af413a sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc413a)
#16 0x00007fff12af1880 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc1880)
#17 0x00007fff12af2467 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc2467)
#18 0x00007fff12af54d1 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc54d1)
#19 0x00007fff12af4aa1 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc4aa1)
#20 0x00007fff12af522e sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc522e)
#21 0x00007fff12af28f7 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc28f7)
#22 0x00007fff12af6746 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc6746)
#23 0x00007fff12af4732 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc4732)
#24 0x00007fff12af522e sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc522e)
#25 0x00007fff12af28f7 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc28f7)
#26 0x00007fff12af6da6 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1fc6da6)
#27 0x00007fff129c2c0a sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x1e92c0a)
#28 0x00007fff11de4129 sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x12b4129)
#29 0x00007fff10f9419e sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x46419e)
#30 0x00007fff10fa71fe sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x4771fe)
#31 0x00007fff10cb161e sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x18161e)
#32 0x00007fff10cb164e sourcekitd_set_uid_handlers (C:\Users\User\AppData\Local\Programs\Swift\Toolchains\6.2.0+Asserts\usr\bin\sourcekitdInProc.dll+0x18164e)
#33 0x00007fff9a5337b0 (C:\WINDOWS\System32\ucrtbase.dll+0x37b0)
#34 0x00007fff9b58e8d7 (C:\WINDOWS\System32\KERNEL32.DLL+0x2e8d7)
#35 0x00007fff9d3a8d9c (C:\WINDOWS\SYSTEM32\ntdll.dll+0x8d9c)
[Info  - 10:11:53 PM] Connection to server got closed. Server will restart.

sourcekit-lsp-diagnose-2025-10-03T19-33-36Z.zip