[SR-7466] Compiler crash when referencing instance member as default parameter

[swift-ci]

Previous ID	SR-7466
Radar	None
Original Reporter	allewun (JIRA User)
Type	Bug
Status	Resolved
Resolution	Duplicate

Environment

Swift 4.0, Xcode 9.2

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, CompilerCrash
Assignee	None
Priority	Medium

md5: d8fe33131133499279230b868d053712

duplicates:

• SR-2189 Nested function with local default value crashes

relates to:

• SR-2189 Nested function with local default value crashes

Issue Description:

Swift doesn't allow using instance members as default parameters for methods.

This emits a compiler warning "Cannot use instance member 'humanLifespan' as default parameter":

class Person {
    let humanLifespan: Int = 200
    
    func _isAlive(at age: Int, maxAge: Int = humanLifespan) -> Bool {
        return age <= maxAge
    }
}

But if the function is nested in another function, I get a compiler crash instead:

class Person {
    let humanLifespan: Int = 200
    
    func isAlive(at age: Int) -> Bool {
        func _isAlive(at age: Int, maxAge: Int = humanLifespan) -> Bool {
            return age <= maxAge
        }
        
        return _isAlive(at: age)
    }
}

Command failed due to signal: Abort trap: 6

Global is external, but doesn't have external or weak linkage!
i8* ()* @_T04test6PersonC7isAliveSbSi2at_tF4selfL_ACfau
<unknown>:0: error: fatal error encountered during compilation; please file a bug report with your project and the crash log
<unknown>:0: note: Broken module found, compilation aborted!
0  swift                    0x000000010667836a PrintStackTraceSignalHandler(void*) + 42
1  swift                    0x00000001066777a6 SignalHandler(int) + 662
2  libsystem_platform.dylib 0x00007fff994f1b3a _sigtramp + 26
3  libsystem_platform.dylib 0x0000000000000004 _sigtramp + 1722868964
4  libsystem_c.dylib        0x00007fff99376420 abort + 129
5  swift                    0x0000000102fd1a57 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*)::$_0::__invoke(void*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool) + 551
6  swift                    0x0000000106635adb llvm::report_fatal_error(llvm::Twine const&, bool) + 571
7  swift                    0x000000010663589a llvm::report_fatal_error(char const*, bool) + 42
8  swift                    0x000000010660bd34 (anonymous namespace)::VerifierLegacyPass::doFinalization(llvm::Module&) + 260
9  swift                    0x00000001065b8985 llvm::FPPassManager::doFinalization(llvm::Module&) + 53
10 swift                    0x00000001065bdbd7 llvm::legacy::FunctionPassManagerImpl::doFinalization(llvm::Module&) + 71
11 swift                    0x00000001031501e5 swift::performLLVM(swift::IRGenOptions&, swift::DiagnosticEngine*, llvm::sys::SmartMutex<false>*, llvm::GlobalVariable*, llvm::Module*, llvm::TargetMachine*, swift::version::Version const&, llvm::StringRef, swift::UnifiedStatsReporter*) + 5045
12 swift                    0x0000000102fd64ce performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 19054
13 swift                    0x0000000102fd01f4 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 7716
14 swift                    0x0000000102f84e78 main + 12248
15 libdyld.dylib            0x00007fff992e2235 start + 1
16 libdyld.dylib            0x0000000000000043 start + 1725029903

[belkadan]

@slavapestov, should we call this the same as SR-2189, or is it worth keeping separate?