Open Radar

 
Summary:
If a closure with an inferred type is created and immediately called (i.e. not assigned to a variable first) and is passed a variable defined as a var, it will trigger a compiler crash in Xcode 6.1 (6A1042b).

Steps to Reproduce:
1. Install Xcode 6.1 (6A1042b)
2. Create a new OS X command line tool project with its language set to Swift
3. Replace the code in main.swift with the following:

    var index = 1
    _ = {
        println($0)
    } (index)

4. Build the project

Expected Results:
A compiled binary

Actual Results:
Swift Compiler Error: Command failed due to signal: Segmentation fault: 11

0  swift                    0x0000000107c4bf68 llvm::sys::PrintStackTrace(__sFILE*) + 40
1  swift                    0x0000000107c4c454 SignalHandler(int) + 452
2  libsystem_platform.dylib 0x00007fff97762f1a _sigtramp + 26
3  libsystem_platform.dylib 000000000000000000 _sigtramp + 1753862400
4  swift                    0x000000010801025c swift::NominalTypeDecl::getMembers(bool) const + 28
5  swift                    0x00000001070a6fe8 (anonymous namespace)::LowerType::visitAnyStructType(swift::CanType, swift::StructDecl*) + 40
6  swift                    0x00000001070a4c3d swift::Lowering::TypeLowering const* swift::CanTypeVisitor<(anonymous namespace)::LowerType, swift::Lowering::TypeLowering const*>::visit<>(swift::CanType) + 125
7  swift                    0x00000001070a4ab7 swift::Lowering::TypeConverter::getTypeLoweringForUncachedLoweredType(swift::Lowering::TypeConverter::TypeKey) + 263
8  swift                    0x00000001070a43af swift::Lowering::TypeConverter::getTypeLowering(swift::Lowering::AbstractionPattern, swift::Type, unsigned int) + 1999
9  swift                    0x000000010706ebf4 (anonymous namespace)::DestructureInputs::visitType(swift::CanType, swift::CanType) + 52
10 swift                    0x000000010706e76c getSILFunctionType(swift::SILModule&, swift::CanType, swift::CanTypeWrapper<swift::AnyFunctionType>, swift::CanTypeWrapper<swift::AnyFunctionType>, swift::AnyFunctionType::ExtInfo, (anonymous namespace)::Conventions const&) + 556
11 swift                    0x000000010706c6e8 getUncachedSILFunctionTypeForConstant(swift::SILModule&, swift::SILDeclRef, swift::CanTypeWrapper<swift::AnyFunctionType>, swift::CanTypeWrapper<swift::AnyFunctionType>, swift::CanTypeWrapper<swift::AnyFunctionType>, swift::CanTypeWrapper<swift::AnyFunctionType>, swift::AnyFunctionType::Representation) + 776
12 swift                    0x000000010706c2d3 swift::Lowering::TypeConverter::getConstantInfo(swift::SILDeclRef) + 691
13 swift                    0x00000001070b992c swift::Lowering::SILGenModule::getFunction(swift::SILDeclRef, swift::ForDefinition_t) + 204
14 swift                    0x00000001070bc60b swift::SILFunction* swift::Lowering::SILGenModule::preEmitFunction<swift::AbstractClosureExpr>(swift::SILDeclRef, swift::AbstractClosureExpr*, swift::SILLocation) + 91
15 swift                    0x00000001070ba897 swift::Lowering::SILGenModule::emitClosure(swift::AbstractClosureExpr*) + 119
16 swift                    0x00000001070f5491 (anonymous namespace)::RValueEmitter::visitAbstractClosureExpr(swift::AbstractClosureExpr*, swift::Lowering::SGFContext) + 97
17 swift                    0x00000001070e7d86 swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) + 2870
18 swift                    0x00000001070f05dd swift::Lowering::

Version:
Xcode 6.1 (6A1042b)

Notes:
There are two workarounds:

1. Define the variable passed to the closure as a let:

    let index = 1
    _ = {
        println($0)
    } (index)

2. Explicitly define the type of the parameter in the closure:

    var index = 1
    _ = { (i: Int) in
        println(i)
    } (index)


Configuration:
iMac (27-inch, Late 2012)
3.4 GHz Intel Core i7
24 GB 1600 MHz DDR3
NVIDIA GeForce GTX 680MX 2048 MB

OS X Yosemite 10.10 (14A379a)