error.txt

$ swift tree.swift 
tree.swift:1:8: error: recursive value type 'Node' is not allowed
struct Node {
       ^
0  swift                    0x000000010248933b llvm::sys::PrintStackTrace(__sFILE*) + 43
1  swift                    0x0000000102489a7b SignalHandler(int) + 379
2  libsystem_platform.dylib 0x00007fff95d1bf1a _sigtramp + 26
3  libsystem_platform.dylib 0x00007fff5f689e20 _sigtramp + 3382107936
4  swift                    0x000000010067889b swift::irgen::TypeConverter::convertAnyNominalType(swift::CanType, swift::NominalTypeDecl*) + 379
5  swift                    0x0000000100678295 swift::irgen::TypeConverter::convertType(swift::CanType) + 181
6  swift                    0x00000001006779ad swift::irgen::TypeConverter::getTypeEntry(swift::CanType) + 621
7  swift                    0x0000000100677534 swift::irgen::IRGenModule::getTypeInfo(swift::SILType) + 20
8  swift                    0x0000000100651326 addValueWitnessesForAbstractType(swift::irgen::IRGenModule&, swift::CanType, llvm::SmallVectorImpl<llvm::Constant*>&) + 102
9  swift                    0x0000000100651226 swift::irgen::emitValueWitnessTable(swift::irgen::IRGenModule&, swift::CanType) + 70
10 swift                    0x000000010062493b swift::irgen::emitStructMetadata(swift::irgen::IRGenModule&, swift::StructDecl*) + 443
11 swift                    0x0000000100669d42 swift::irgen::IRGenModule::emitStructDecl(swift::StructDecl*) + 18
12 swift                    0x00000001005fb927 swift::irgen::IRGenModule::emitSourceFile(swift::SourceFile&, unsigned int) + 87
13 swift                    0x000000010067e635 performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, swift::SourceFile*, unsigned int) + 933
14 swift                    0x000000010067d5a6 swift::performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&) + 598
15 swift                    0x000000010088e3ba swift::RunImmediately(swift::CompilerInstance&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, swift::IRGenOptions&, swift::SILOptions const&) + 154
16 swift                    0x000000010057d351 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&) + 13425
17 swift                    0x0000000100579cd3 frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2691
18 swift                    0x0000000100576354 main + 2324
19 libdyld.dylib            0x00007fff8f1065c9 start + 1
Stack dump:
0.	Program arguments: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -interpret tree.swift -target x86_64-apple-darwin14.5.0 -enable-objc-interop -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk -color-diagnostics -module-name tree 
1.	While emitting IR for source file tree.swift
2.	While converting type 'Node' (declared at [tree.swift:1:1 - line:5:1] RangeText="struct Node {
    let value: Int
    let left: Node
    let right: Node
}")
Segmentation fault: 11

tree.swift

struct Node {
    let value: Int
    let left: Node
    let right: Node
}