Radar 18996669: Swift: Attempting to instantiate instance via class pointer crashes

instantiate-from-class.swift

/*
Radar 18996669: Swift: Attempting to instantiate instance via class pointer crashes

% xcrun -sdk macosx swiftc instantiate-from-class.swift
0  swift                    0x0000000107668b68 llvm::sys::PrintStackTrace(__sFILE*) + 40
1  swift                    0x0000000107669054 SignalHandler(int) + 452
2  libsystem_platform.dylib 0x00007fff95c74f1a _sigtramp + 26
3  libsystem_platform.dylib 0x0000000108bd3e00 _sigtramp + 1928720128
4  swift                    0x0000000107a675fc collectFullName(swift::ArchetypeType const*, llvm::SmallVectorImpl<char>&) + 92
5  swift                    0x0000000107a675c8 collectFullName(swift::ArchetypeType const*, llvm::SmallVectorImpl<char>&) + 40
6  swift                    0x0000000107a675c8 collectFullName(swift::ArchetypeType const*, llvm::SmallVectorImpl<char>&) + 40
7  swift                    0x0000000107a67551 swift::ArchetypeType::getFullName() const + 49
8  swift                    0x0000000106a31716 swift::irgen::IRGenFunction::bindArchetype(swift::ArchetypeType*, llvm::Value*, llvm::ArrayRef<llvm::Value*>) + 70
9  swift                    0x0000000106a35c56 swift::irgen::emitClassExistentialProjection(swift::irgen::IRGenFunction&, swift::irgen::Explosion&, swift::SILType, swift::CanTypeWrapper<swift::ArchetypeType>) + 102
10 swift                    0x0000000106a7348e swift::SILVisitor<(anonymous namespace)::IRGenSILFunction, void>::visit(swift::ValueBase*) + 23310
11 swift                    0x0000000106a6cd3b swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 9179
12 swift                    0x00000001069e6447 swift::irgen::IRGenModule::emitLazyDefinitions() + 199
13 swift                    0x0000000106a59af6 performIRGeneration(swift::IRGenOptions&, swift::Module*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, swift::SourceFile*, unsigned int) + 2038
14 swift                    0x0000000106a5a473 swift::performIRGeneration(swift::IRGenOptions&, swift::SourceFile&, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, unsigned int) + 51
15 swift                    0x00000001069af6f4 frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 5444
16 swift                    0x00000001069aca6d main + 1677
17 libdyld.dylib            0x00007fff981545c9 start + 1
18 libdyld.dylib            0x0000000000000010 start + 1743436360
Stack dump:
0.	Program arguments: /Applications/Xcode 6.1.1 GM.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c -primary-file instantiate-from-class.swift -target x86_64-apple-darwin14.0.0 -target-cpu core2 -sdk /Applications/Xcode 6.1.1 GM.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -color-diagnostics -module-name main -o /var/folders/wc/zbg165dn60d1glkwdnd7cq780000gp/T/instantiate-from-class-d67574.o 
1.	While emitting IR SIL function @top_level_code<unknown>:0: error: unable to execute command: Segmentation fault: 11
<unknown>:0: error: swift frontend command failed due to signal (use -v to see invocation)

*/

protocol P {
  class var name: String { get }
  init(i:Int)
}

class A: P {
  class var name: String {
    get { return "A" }
  }
  required init(i:Int) {}
}
class B: P {
  class var name: String {
    get { return "A" }
  }
  required init(i:Int) {}
}

let cls:P.Type = A.self

let p:P = cls(i:1)