We can analyze the crash by checking the assembly code.
Add a breakpoint on the following function would not give us what we want (The problem is crashing when entering this function)
public mutating func bind<SourceJob: Job<Value>>(@JobBuilder<Value> builder: () throws -> SourceJob) rethrows {
bind(job: try builder())
}
So let's do it by hand.
Assembly Journey
Env: Xcode 15.0 + iOS 17(21A328) Simulator
Checking the second crash stack it was jumped into at +536
We rewrite the code and run it again
init() {
var a = self.$count
a.bind { // Add a breakpoint here
ThrowingJob()
.mapToResult()
}
}
Add a breakpoint on line 3 and then get the address for <+536> (eg. 0x10d5170d0)
0x10d5170d0 <+536>: bl 0x10d69b748 ; symbol stub for: Kubrick.JobBinding.bind<τ_0_0 where τ_0_0 == τ_1_0.Value, τ_1_0: Kubrick.Job>(builder: () throws -> τ_1_0) throws -> ()
b 0x10d69b748
continue
KubrickHostTests`Kubrick.JobBinding.bind<τ_0_0 where τ_0_0 == τ_1_0.Value, τ_1_0: Kubrick.Job>(builder: () throws -> τ_1_0) throws -> ():
-> 0x10d69b748 <+0>: adrp x16, 49
0x10d69b74c <+4>: ldr x16, [x16, #0xb8]
0x10d69b750 <+8>: br x16
Add a breakpoint on br x16
continue
reg read x16
// x16 = 0x000000010048fbf8 KubrickHost`Kubrick.JobBinding.bind<Value where Value == SourceJob.Value, SourceJob: Kubrick.Job>(builder: () throws -> SourceJob) throws -> () at JobBinding.swift:63**
b 0x000000010048fbf8
continue
KubrickHost`JobBinding.bind<τ_0_0>(builder:):
-> 0x10048fbf8 <+0>: str x20, [sp, #-0x20]!
0x10048fbfc <+4>: stp x29, x30, [sp, #0x10]
0x10048fc00 <+8>: add x29, sp, #0x10
0x10048fc04 <+12>: sub sp, sp, #0x70
0x10048fc08 <+16>: stur x1, [x29, #-0x68]
0x10048fc0c <+20>: stur x2, [x29, #-0x80]
0x10048fc10 <+24>: stur x3, [x29, #-0x78]
0x10048fc14 <+28>: stur x4, [x29, #-0x70]
0x10048fc18 <+32>: mov x9, x20
0x10048fc1c <+36>: ldur x20, [x29, #-0x68]
0x10048fc20 <+40>: stur x9, [x29, #-0x60]
0x10048fc24 <+44>: stur xzr, [x29, #-0x28]
0x10048fc28 <+48>: stur xzr, [x29, #-0x20]
0x10048fc2c <+52>: stur xzr, [x29, #-0x30]
0x10048fc30 <+56>: mov x8, x3
0x10048fc34 <+60>: stur x8, [x29, #-0x18]
0x10048fc38 <+64>: ldur x8, [x3, #-0x8]
It will then crash on 0x10048fc38 <+64>: ldur x8, [x3, #-0x8] because x3 is 0x0 - nil.
Normally this is used to get VWT for x3's type.
After this, there will be 2 ways to keep working on the issue IMO. @Kevin_Wooten
- Checking where x3 is from
- Diff the generated assembly code running in SwiftPM or iOS 16 to see why it's not crashing.
Checking where x3 is from
0x10b687008 <+336>: adrp x0, 455
0x10b68700c <+340>: add x0, x0, #0x270 ; demangling cache variable for type metadata for <<opaque return type of static Kubrick.JobBuilder.buildBlock<τ_0_0 where τ_0_0 == τ_1_0.Value, τ_1_0: Kubrick.Job>(τ_1_0) -> some>>.0
-> 0x10b687010 <+344>: bl 0x10b646db8 ; __swift_instantiateConcreteTypeFromMangledName at <compiler-generated>
0x10b687014 <+348>: stur x0, [x29, #-0x78]
...
0x10b6870c0 <+520>: ldur x3, [x29, #-0x78]
...
0x10b6870d0 <+536>: bl 0x10b80b748 ; symbol stub for: Kubrick.JobBinding.bind<Value where Value == SourceJob.Value, SourceJob: Kubrick.Job>(builder: () throws -> SourceJob) throws -> ()
The result of 0x10b646db8 is 0 (stored on x0) which is unexpected.
Diff running on SwiftPM
Again, we need some patch here to work on your branch 
dependencies: [
...
.package(url: "https://github.com/outfoxx/sunday-swift", exact: "1.0.0-beta.27"),
],
targets: [
...
.testTarget(
name: "KubrickTests",
dependencies: [
"Kubrick",
.product(name: "Sunday", package: "sunday-swift"),
.product(name: "SundayServer", package: "sunday-swift")
]
)
]
Notably it only fails when called from an Xcode project (when the package is used directly in an application or embedded in a framework) and only on the latest operating systems. Originally, the tests were ran using a Swift Test Package where it doesn't crash and it also doesn't crash when running on macOS 13, iOS 16, or tvOS 16.
And actually it also crashes on my environment. So could you double check it again and update the description if needed.
Diff running on iOS 15
- SwiftPM testTarget + iOS 15(19F70) Simulator
SwiftPM tells me that iOS 15's libswiftCore does not include the symbol we need.
2023-11-02 21:06:05.568836+0800 xctest[62989:13665967] [Default] 未能载入软件包“KubrickTests”。 请尝试重新安装软件包。
2023-11-02 21:06:05.569053+0800 xctest[62989:13665967] [Default] (dlopen(xx/Build/Products/Debug-iphonesimulator/KubrickTests.xctest/KubrickTests, 0x0109): Symbol not found: _swift_getExtendedExistentialTypeMetadata
Referenced from: xx/Build/Products/Debug-iphonesimulator/KubrickTests.xctest/KubrickTests
Expected in: /Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 15.5.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift/libswiftCore.dylib)
Program ended with exit code: 83
- Xcodeproj + iOS 15(19F70) Simulator
The same crash when running host app
**dyld[66441]: Symbol not found: _swift_getExtendedExistentialTypeMetadata**
And infinite loading when running hostTest
