Greg,
This occurs when compiled with swiftc -g as well. In fact, I think 'swift
build', when run by default, will compile with swiftc -g. It's only when you
run 'swift build --configuration release' that it will compile without it.
$ swiftc --version
Apple Swift version 3.1 (swift-3.1.1-RELEASE)
Target: x86_64-apple-macosx10.9
$ swiftc -g main.swift
$ ./main
Hello, world!
fatal error: unexpectedly found nil while unwrapping an Optional value
Current stack trace:
0 libswiftCore.dylib 0x000000010edc7160 swift_reportError +
125
1 libswiftCore.dylib 0x000000010ede3ac0
_swift_stdlib_reportFatalError + 60
2 libswiftCore.dylib 0x000000010ebd4260 specialized
specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) -> A)
-> A + 342
3 libswiftCore.dylib 0x000000010ed4f120 partial apply for
(_fatalErrorMessage(StaticString, StaticString, file : StaticString, line :
UInt, flags : UInt32) -> Never).(closure #2) + 109
4 libswiftCore.dylib 0x000000010ebd4260 specialized
specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) -> A)
-> A + 342
5 libswiftCore.dylib 0x000000010ed01d00 specialized
_fatalErrorMessage(StaticString, StaticString, file : StaticString, line :
UInt, flags : UInt32) -> Never + 96
6 main 0x000000010eb91340 say(message :
String?) -> () + 248
7 main 0x000000010eb911e0 main + 328
8 libdyld.dylib 0x00007fffb444d234 start + 1
Illegal instruction: 4
Note that lldb can symbolicate the result and identify the return value, by
looking at the backtrace:
$ lldb main
(lldb) target create "main"
Current executable set to 'main' (x86_64).
(lldb) run
Process 33032 launched: '/tmp/main' (x86_64)
Hello, world!
fatal error: unexpectedly found nil while unwrapping an Optional value
2017-05-03 10:41:17.340963+0100 main[33032:55100807] fatal error: unexpectedly
found nil while unwrapping an Optional value
Current stack trace:
0 libswiftCore.dylib 0x00000001002c1160 swift_reportError +
125
1 libswiftCore.dylib 0x00000001002ddac0
_swift_stdlib_reportFatalError + 60
2 libswiftCore.dylib 0x00000001000ce260 specialized
specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) -> A)
-> A + 342
3 libswiftCore.dylib 0x0000000100249120 partial apply for
(_fatalErrorMessage(StaticString, StaticString, file : StaticString, line :
UInt, flags : UInt32) -> Never).(closure #2) + 109
4 libswiftCore.dylib 0x00000001000ce260 specialized
specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) -> A)
-> A + 342
5 libswiftCore.dylib 0x00000001001fbd00 specialized
_fatalErrorMessage(StaticString, StaticString, file : StaticString, line :
UInt, flags : UInt32) -> Never + 96
6 main 0x0000000100001340 say(message :
String?) -> () + 248
7 main 0x00000001000011e0 main + 328
8 libdyld.dylib 0x00007fffb444d234 start + 1
Process 33032 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION
(code=EXC_I386_INVOP, subcode=0x0)
frame #0: 0x00000001001fbd60 libswiftCore.dylib`function signature
specialization <preserving fragile attribute, Arg[2] = Dead, Arg[3] = Dead> of
Swift._fatalErrorMessage (Swift.StaticString, Swift.StaticString, file :
Swift.StaticString, line : Swift.UInt, flags : Swift.UInt32) -> Swift.Never + 96
libswiftCore.dylib`function signature specialization <preserving fragile
attribute, Arg[2] = Dead, Arg[3] = Dead> of Swift._fatalErrorMessage
(Swift.StaticString, Swift.StaticString, file : Swift.StaticString, line :
Swift.UInt, flags : Swift.UInt32) -> Swift.Never:
-> 0x1001fbd60 <+96>: ud2
0x1001fbd62 <+98>: nopw %cs:(%rax,%rax)
libswiftCore.dylib`protocol witness table accessor for <A> Swift.AnySequence<A>
: Swift.Sequence in Swift:
0x1001fbd70 <+0>: pushq %rbp
0x1001fbd71 <+1>: movq %rsp, %rbp
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION
(code=EXC_I386_INVOP, subcode=0x0)
* frame #0: 0x00000001001fbd60 libswiftCore.dylib`function signature
specialization <preserving fragile attribute, Arg[2] = Dead, Arg[3] = Dead> of
Swift._fatalErrorMessage (Swift.StaticString, Swift.StaticString, file :
Swift.StaticString, line : Swift.UInt, flags : Swift.UInt32) -> Swift.Never + 96
frame #1: 0x0000000100001438 main`say(message=nil) -> () at main.swift:5
frame #2: 0x0000000100001328 main`main at main.swift:8
frame #3: 0x00007fffb444d235 libdyld.dylib`start + 1
frame #4: 0x00007fffb444d235 libdyld.dylib`start + 1
I suspect this is because Swift is generating a .dSYM which is read by LLDB but
either not read or not loaded by the swift runtime when producing the backtrace:
$ find .
.
./main
./main.dSYM
./main.dSYM/Contents
./main.dSYM/Contents/Info.plist
./main.dSYM/Contents/Resources
./main.dSYM/Contents/Resources/DWARF
./main.dSYM/Contents/Resources/DWARF/main
./main.swift
Here's the main file, for repeatability:
$ cat main.swift
print("Hello, world!")
let x: String? = nil
func say(message: String?) {
print(x!) // intentional crash
}
say(message: x)
Alex
> On 2 May 2017, at 22:43, Greg Parker <gpar...@apple.com> wrote:
>
> That doesn't look symbolicated. If it were symbolicated, and the build used
> -g, you would have a file and line number for the main+345 frame.
>
>
>> On May 2, 2017, at 2:31 PM, Nick Snyder via swift-users
>> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
>>
>> In practice, I would need the stack trace first to figure out how to
>> reproduce the issue, so lldb doesn't really help.
>>
>> How would I go about symbolicating this further on macOS (Xcode or
>> otherwise)?
>>
>> From reading the docs it seems like the crash report I get is already
>> completely symbolicated:
>> https://developer.apple.com/library/content/technotes/tn2151/_index.html#//apple_ref/doc/uid/DTS40008184-CH1-SYMBOLICATION-_DETERMINING_WHETHER_A_CRASH_REPORT_IS_SYMBOLICATED
>>
>> <https://developer.apple.com/library/content/technotes/tn2151/_index.html#//apple_ref/doc/uid/DTS40008184-CH1-SYMBOLICATION-_DETERMINING_WHETHER_A_CRASH_REPORT_IS_SYMBOLICATED>
>>
>> On Tue, May 2, 2017 at 1:21 AM, Alex Blewitt <alb...@apple.com
>> <mailto:alb...@apple.com>> wrote:
>> If you can reproduce it, and run it under lldb, it will print the source
>> line for you:
>>
>> $ lldb .build/debug/main
>> (lldb) target create ".build/debug/main"
>> ruCurrent executable set to '.build/debug/main' (x86_64).
>> (lldb) run
>> Process 19013 launched: '/private/tmp/main/.build/debug/main' (x86_64)
>> Hello, world!
>> fatal error: unexpectedly found nil while unwrapping an Optional value
>> 2017-05-02 09:17:11.351608+0100 asdf[19013:54205130] fatal error:
>> unexpectedly found nil while unwrapping an Optional value
>> Current stack trace:
>> 0 libswiftCore.dylib 0x00000001002c1160 swift_reportError
>> + 125
>> 1 libswiftCore.dylib 0x00000001002ddac0
>> _swift_stdlib_reportFatalError + 60
>> 2 libswiftCore.dylib 0x00000001000ce260 specialized
>> specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) ->
>> A) -> A + 342
>> 3 libswiftCore.dylib 0x0000000100249120 partial apply for
>> (_fatalErrorMessage(StaticString, StaticString, file : StaticString, line :
>> UInt, flags : UInt32) -> Never).(closure #2) + 109
>> 4 libswiftCore.dylib 0x00000001000ce260 specialized
>> specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) ->
>> A) -> A + 342
>> 5 libswiftCore.dylib 0x00000001001fbd00 specialized
>> _fatalErrorMessage(StaticString, StaticString, file : StaticString, line :
>> UInt, flags : UInt32) -> Never + 96
>> 6 main 0x0000000100001340 say(message :
>> String?) -> () + 248
>> 7 main 0x00000001000011e0 main + 328
>> 8 libdyld.dylib 0x00007fffb444d234 start + 1
>> Process 19013 stopped
>> * thread #1, queue = 'com.apple.main-thread', stop reason =
>> EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
>> frame #0: 0x00000001001fbd60 libswiftCore.dylib`function signature
>> specialization <preserving fragile attribute, Arg[2] = Dead, Arg[3] = Dead>
>> of Swift._fatalErrorMessage (Swift.StaticString, Swift.StaticString, file :
>> Swift.StaticString, line : Swift.UInt, flags : Swift.UInt32) -> Swift.Never
>> + 96
>> libswiftCore.dylib`function signature specialization <preserving fragile
>> attribute, Arg[2] = Dead, Arg[3] = Dead> of Swift._fatalErrorMessage
>> (Swift.StaticString, Swift.StaticString, file : Swift.StaticString, line :
>> Swift.UInt, flags : Swift.UInt32) -> Swift.Never:
>> -> 0x1001fbd60 <+96>: ud2
>> 0x1001fbd62 <+98>: nopw %cs:(%rax,%rax)
>>
>> libswiftCore.dylib`protocol witness table accessor for <A>
>> Swift.AnySequence<A> : Swift.Sequence in Swift:
>> 0x1001fbd70 <+0>: pushq %rbp
>> 0x1001fbd71 <+1>: movq %rsp, %rbp
>>
>> (lldb) bt
>> * thread #1, queue = 'com.apple.main-thread', stop reason =
>> EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
>> * frame #0: 0x00000001001fbd60 libswiftCore.dylib`function signature
>> specialization <preserving fragile attribute, Arg[2] = Dead, Arg[3] = Dead>
>> of Swift._fatalErrorMessage (Swift.StaticString, Swift.StaticString, file :
>> Swift.StaticString, line : Swift.UInt, flags : Swift.UInt32) -> Swift.Never
>> + 96
>> frame #1: 0x0000000100001438 main`say(message=nil) -> () at main.swift:5
>> frame #2: 0x0000000100001328 main`main at main.swift:8
>> frame #3: 0x00007fffb444d235 libdyld.dylib`start + 1
>> frame #4: 0x00007fffb444d235 libdyld.dylib`start + 1
>>
>> There is a symbolication tool available for Linux in the
>> ~/swift/utils/symbolicate-linux-fatal, and Xcode can do the same
>> symbolication for you as well.
>>
>> Alex
>>
>>> On 28 Apr 2017, at 22:28, Nick Snyder via swift-users
>>> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
>>>
>>> I have a simple main.swift that looks like this:
>>>
>>> ```
>>> print("Hello, world!")
>>> let x: String? = nil
>>>
>>> func say(message: String?) {
>>> print(x!) // intentional crash
>>> }
>>>
>>> say(message: x)
>>> ```
>>>
>>> Running this results in the crash
>>>
>>> ```
>>> $ swift build && ./.build/debug/hello
>>> Hello, world!
>>> fatal error: unexpectedly found nil while unwrapping an Optional value
>>> Current stack trace:
>>> 0 libswiftCore.dylib 0x0000000110120130
>>> swift_reportError + 129
>>> 1 libswiftCore.dylib 0x000000011013cb50
>>> _swift_stdlib_reportFatalError + 60
>>> 2 libswiftCore.dylib 0x000000010ff2d250 specialized
>>> specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) ->
>>> A) -> A + 342
>>> 3 libswiftCore.dylib 0x00000001100a7e90 partial apply
>>> for (_fatalErrorMessage(StaticString, StaticString, file : StaticString,
>>> line : UInt, flags : UInt32) -> Never).(closure #2) + 109
>>> 4 libswiftCore.dylib 0x000000010ff2d250 specialized
>>> specialized StaticString.withUTF8Buffer<A> ((UnsafeBufferPointer<UInt8>) ->
>>> A) -> A + 342
>>> 5 libswiftCore.dylib 0x000000011005a9a0 specialized
>>> _fatalErrorMessage(StaticString, StaticString, file : StaticString, line :
>>> UInt, flags : UInt32) -> Never + 96
>>> 6 hello 0x000000010fee6200 main + 345
>>> 7 libdyld.dylib 0x00007fffe0375234 start + 1
>>> Illegal instruction: 4
>>> ```
>>>
>>> From the crash, how do I map back line 6 to an actual line in main.swift?
>>> _______________________________________________
>>> swift-users mailing list
>>> swift-users@swift.org <mailto:swift-users@swift.org>
>>> https://lists.swift.org/mailman/listinfo/swift-users
>>> <https://lists.swift.org/mailman/listinfo/swift-users>
>>
>>
>> _______________________________________________
>> swift-users mailing list
>> swift-users@swift.org <mailto:swift-users@swift.org>
>> https://lists.swift.org/mailman/listinfo/swift-users
>
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