Open Radar

 
Summary:
The following code crashes the Swift compiler:

Steps to Reproduce:
import Foundation

class BinaryHeap<T: AnyObject where T: Comparable>
{
    let heap: CFBinaryHeap
    init() {
        var callbacks = CFBinaryHeapCallBacks(
            version: 0,
            retain: { _, obj in
                Unmanaged<T>.fromOpaque(COpaquePointer(obj)).retain()
                return obj
            },
            release: { _, obj in
                Unmanaged<T>.fromOpaque(COpaquePointer(obj)).release()
            },
            copyDescription: { obj in
                let o = Unmanaged<T>.fromOpaque(COpaquePointer(obj)).takeUnretainedValue()
                return Unmanaged.passRetained(String(o) as CFString)
            },
            compare: { obj1, obj2, _ in
                let o1 = Unmanaged<T>.fromOpaque(COpaquePointer(obj1)).takeUnretainedValue()
                let o2 = Unmanaged<T>.fromOpaque(COpaquePointer(obj2)).takeUnretainedValue()
                if o1 == o2 { return .CompareEqualTo }
                if o1 < o2 { return .CompareLessThan }
                return .CompareGreaterThan
            }
        )
        heap = CFBinaryHeapCreate(nil, 0, &callbacks, nil)
    }
}

Expected Results:
No crash.

Actual Results:
Segfault:

0  swift                    0x0000000105ddc33b llvm::sys::PrintStackTrace(__sFILE*) + 43
1  swift                    0x0000000105ddca7b SignalHandler(int) + 379
2  libsystem_platform.dylib 0x00007fff9d65beaa _sigtramp + 26
3  libsystem_platform.dylib 0x0000000000000003 _sigtramp + 1654276467
4  swift                    0x0000000103fac4ab swift::irgen::emitPolymorphicArguments(swift::irgen::IRGenFunction&, swift::CanTypeWrapper<swift::SILFunctionType>, swift::CanTypeWrapper<swift::SILFunctionType>, llvm::ArrayRef<swift::Substitution>, swift::irgen::WitnessMetadata*, swift::irgen::Explosion&) + 587
5  swift                    0x0000000103ff90ac (anonymous namespace)::IRGenSILFunction::visitFullApplySite(swift::FullApplySite) + 2172
6  swift                    0x0000000103feabad swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 10973
7  swift                    0x0000000103f51253 swift::irgen::IRGenModuleDispatcher::emitLazyDefinitions() + 307
8  swift                    0x0000000103fd169a performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, swift::SourceFile*, unsigned int) + 1034
9  swift                    0x0000000103fd1a30 swift::performIRGeneration(swift::IRGenOptions&, swift::SourceFile&, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, unsigned int) + 64
10 swift                    0x0000000103ed0465 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&) + 13701
11 swift                    0x0000000103ecccd3 frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2691
12 swift                    0x0000000103ec9354 main + 2324
13 libdyld.dylib            0x00007fff9e79f5ad start + 1
14 libdyld.dylib            0x000000000000000f start + 1636174435
Stack dump:
0.	Program arguments: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c -primary-file - -target x86_64-apple-darwin15.2.0 -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk -color-diagnostics -module-name main -o /var/folders/lp/hlnmlhtn79s4qvxx8c7bppbw0000gn/T/--d9fefa.o 
1.	While emitting IR SIL function @_TToFFC4main10BinaryHeapcuRq_Ss9AnyObjectq_Ss10Comparable_FMGS0_q__FT_GS0_q__U2_FTGVSs13UnsafePointerT__GS3_T__GVSs20UnsafeMutablePointerT___OSC18CFComparisonResult for expression at [<stdin>:20:22 - line:26:13] RangeText="{ obj1, obj2, _ in
                let o1 = Unmanaged<T>.fromOpaque(COpaquePointer(obj1)).takeUnretainedValue()
                let o2 = Unmanaged<T>.fromOpaque(COpaquePointer(obj2)).takeUnretainedValue()
                if o1 == o2 { return .CompareEqualTo }
                if o1 < o2 { return .CompareLessThan }
                return .CompareGreaterThan
            }"

Version:
Xcode 7.2 beta (7C46t)
OS X 10.11.2 (15C40a)


Configuration:
Apple Swift version 2.1 (swiftlang-700.1.101.6 clang-700.1.76)
Target: x86_64-apple-darwin15.2.0