Realm-cocoa: Crash when using Results<?>.maximumValue(ofProperty:) with Int64 property

[yangmeyer]

Goals

I want to compare a file’s modification timestamp with that of a Realm model object in order to see whether the database knows about the latest version of the file.

To do this, I ask the RealmSwift.Results for its maximumValue. The fileModificationTime property is modelled as an Int64. This is the line that crashes:

let maxTime = results.maximumValue(ofProperty: "fileModificationTime") as Int64?

Expected Results

To get the maximum value.

Actual Results

A crash. Console output: Could not cast value of type '__NSCFNumber' (0x123a4b608) to 'Swift.Int64' (0x113849298).

(lldb) thread backtrace
* thread #1: tid = 0xd37b, 0x0000000117eabf06 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
    frame #0: 0x0000000117eabf06 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x0000000117f184ec libsystem_pthread.dylib`pthread_kill + 90
    frame #2: 0x0000000117c2b087 libsystem_c.dylib`abort + 129
    frame #3: 0x00000001137df995 libswiftCore.dylib`swift::fatalError(unsigned int, char const*, ...) + 149
    frame #4: 0x00000001137c0303 libswiftCore.dylib`swift::swift_dynamicCastFailure(void const*, char const*, void const*, char const*, char const*) + 83
    frame #5: 0x00000001137c038f libswiftCore.dylib`swift::swift_dynamicCastFailure(swift::TargetMetadata<swift::InProcess> const*, swift::TargetMetadata<swift::InProcess> const*, char const*) + 127
    frame #6: 0x00000001137c2569 libswiftCore.dylib`swift_dynamicCast + 2825
    frame #7: 0x00000001137c2eeb libswiftCore.dylib`_dynamicCastFromExistential(swift::OpaqueValue*, swift::OpaqueValue*, swift::TargetExistentialTypeMetadata<swift::InProcess> const*, swift::TargetMetadata<swift::InProcess> const*, swift::DynamicCastFlags) + 91
    frame #8: 0x00000001137c23fd libswiftCore.dylib`swift_dynamicCast + 2461
    frame #9: 0x00000001103f4a2a RealmSwift`RealmSwift.Results.minimumValue <A where A1: RealmSwift.MinMaxType> (ofProperty : Swift.String) -> Swift.Optional<A1> with unmangled suffix "_merged" + 154
    frame #10: 0x00000001103f4978 RealmSwift`RealmSwift.Results.maximumValue <A where A1: RealmSwift.MinMaxType> (ofProperty : Swift.String) -> Swift.Optional<A1> + 40 at Results.swift:0
  * frame #11: 0x000000010f8c3e08 MyApp`FileDataBlocksDB.isFileUpToDate(path="no-collection/IMG_0007.JPG", fileModified=488735056000, self=0x0000608000235460) -> Bool + 392 at FileDataBlocksDB.swift:35
    frame #12: 0x000000010f8d190e MyApp`FileEngine.(asset=0x00007fd4006380b0, idx=5, _0=0x00007fff50470faf, self=0x0000608000245d30, progress=0x0000608000133e20, fdbDB=0x0000608000235460) throws -> Promise<Progress>).(closure #2).(closure #1) + 990 at BackupEngine.swift:63
    frame #13: 0x000000010f8d1abd MyApp`thunk + 77 at BackupEngine.swift:0
    frame #14: 0x0000000110fa998f CoreFoundation`__NSArrayEnumerate + 607
    frame #15: 0x000000010fc535c3 Photos`-[PHFetchResult enumerateObjectsUsingBlock:] + 79
    frame #16: 0x000000010f8d149b MyApp`BackupEngine.(fetchResult=0x00006080000fcf00, self=0x0000608000245d30, fdbDB=0x0000608000235460) throws -> Promise<Progress>).(closure #2) + 299 at BackupEngine.swift:75
    frame #17: 0x000000010f8d1afd MyApp`thunk + 45 at BackupEngine.swift:0
    frame #18: 0x000000010f8d4999 MyApp`partial apply for thunk + 89 at BackupEngine.swift:0
    frame #19: 0x000000010fe5e3ac PromiseKit`Promise.(resolve=0x000000010fe64170 PromiseKit`partial apply forwarder for reabstraction thunk helper <A> from @callee_owned (@in PromiseKit.Resolution<A>) -> (@out ()) to @callee_owned (@in PromiseKit.Resolution<A>) -> () at Promise.swift, body=0x000000010f8d4940 MyApp`partial apply forwarder for reabstraction thunk helper from @callee_owned (@owned __ObjC.PHFetchResult<__ObjC.PHAsset>) -> (@owned __ObjC.Progress, @error @owned Swift.ErrorProtocol) to @callee_owned (@in __ObjC.PHFetchResult<__ObjC.PHAsset>) -> (@out __ObjC.Progress, @error @owned Swift.ErrorProtocol) at BackupEngine.swift, value=<unavailable>, $error=ErrorProtocol @ 0x00007fff50471360) throws -> A1) -> Promise<A1>).(closure #1).(closure #1) + 172 at Promise.swift:251 [opt]
    frame #20: 0x000000010fe6523a PromiseKit`partial apply for Promise.(then<A> (on : DispatchQueue, execute : (A) throws -> A1) -> Promise<A1>).(closure #1).(closure #1) + 138 at Promise.swift:0 [opt]
    frame #21: 0x000000010fe608da PromiseKit`(block=0x000000010fe651b0 PromiseKit`partial apply forwarder for PromiseKit.Promise.(then <A> (on : __ObjC.DispatchQueue, execute : (A) throws -> A1) -> PromiseKit.Promise<A1>).(closure #1).(closure #1) at Promise.swift, resolve=0x000000010fe64170 PromiseKit`partial apply forwarder for reabstraction thunk helper <A> from @callee_owned (@in PromiseKit.Resolution<A>) -> (@out ()) to @callee_owned (@in PromiseKit.Resolution<A>) -> () at Promise.swift) -> (), block : () throws -> ()) -> ()).(closure #1) + 58 at Promise.swift:536 [opt]
    frame #22: 0x0000000113e554a4 libswiftDispatch.dylib`partial apply forwarder for reabstraction thunk helper from @callee_unowned @convention(block) () -> () to @callee_owned () -> () + 36
    frame #23: 0x0000000117b15637 libdispatch.dylib`_dispatch_call_block_and_release + 12
    frame #24: 0x0000000117b36fdf libdispatch.dylib`_dispatch_client_callout + 8
    frame #25: 0x0000000117b1e4f6 libdispatch.dylib`_dispatch_main_queue_callback_4CF + 1054
    frame #26: 0x0000000110fc6b39 CoreFoundation`__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
    frame #27: 0x0000000110f8d1ed CoreFoundation`__CFRunLoopRun + 2205
    frame #28: 0x0000000110f8c6ed CoreFoundation`CFRunLoopRunSpecific + 285
    frame #29: 0x0000000110557920 Foundation`-[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 274
    frame #30: 0x0000000120cd1430 XCTest`-[XCTestDriver _checkForTestManager] + 258
    frame #31: 0x0000000120d20105 XCTest`_XCTestMain + 628
    frame #32: 0x0000000110fa887c CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #33: 0x0000000110f8d564 CoreFoundation`__CFRunLoopDoBlocks + 356
    frame #34: 0x0000000110f8ccd5 CoreFoundation`__CFRunLoopRun + 901
    frame #35: 0x0000000110f8c6ed CoreFoundation`CFRunLoopRunSpecific + 285
    frame #36: 0x0000000116a46a75 GraphicsServices`GSEventRunModal + 161
    frame #37: 0x0000000111e003b9 UIKit`UIApplicationMain + 159
    frame #38: 0x000000010f8d67bf MyApp`main + 111 at AppDelegate.swift:12
    frame #39: 0x0000000117b8368d libdyld.dylib`start + 1

Steps to Reproduce

1. Create model FileDataBlockDBEntry with Int64 property “fileModificationTime”
2. Try to get maximumValue of this property.

let realm = try! Realm()
let results = realm.allObjects(ofType: FileDataBlockDBEntry.self)
let maxFileModificationTime = results.maximumValue(ofProperty: "fileModificationTime") as Int64?

See also

This commenter seems to have had the same problem:
http://stackoverflow.com/questions/30218827/unable-to-invoke-max-with-an-argument-list-of-type-string#comment62338400_30220258

Version of Realm and Tooling

ProductName:    Mac OS X
ProductVersion: 10.11.5
BuildVersion:   15F34

/Applications/Xcode-beta.app/Contents/Developer
Xcode 8.0
Build version 8S162m (beta 2)

/Users/Yang/.rvm/rubies/ruby-2.2.1/bin/pod
0.37.2
(not in use here)

/bin/bash
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin15)

/usr/local/bin/carthage
0.17.1
github "realm/realm-cocoa" "3fda82279ee4c93ee57b63e5524f83e3a496215f"

/usr/bin/git
git version 2.8.4 (Apple Git-73)

Thanks :)

[yangmeyer]

My current workaround:

let maxTime = results.sorted(onProperty: "fileModificationTime", ascending: false).first?.fileModificationTime

[jpsim]

Thanks for sharing this @yangmeyer. I could reproduce this easily with your instructions. I've labeled this as a bug and hopefully we can resolve quickly.

[JadenGeller]

According to the Swift documentation,

All of the following types are automatically bridged to NSNumber: Int, Uint, Float, Double, Bool

We're incorrectly assuming that types like Int64 and friends are also bridged, and they are not.