Swift 2.2 undefined symbols preventing build - swift

Question

I'm trying to build a project with the new release of the open source Swift 2.2 compiler and am running into a few issues.
A minimal example like this:
.
├── Package.swift
└── Sources
└── main.swift
Package.swift
import PackageDescription
let package = Package(
name: "foo",
dependencies: []
)
main.swift
print("foo")
run via swift build throws the following:
Compiling Swift Module 'foo' (1 sources)
Linking Executable: .build/debug/foo
Undefined symbols for architecture x86_64:
"__TFSSCfT21_builtinStringLiteralBp8byteSizeBw7isASCIIBi1__SS", referenced from:
_main in main.swift.o
"__TFs5printFTGSaP__9separatorSS10terminatorSS_T_", referenced from:
_main in main.swift.o
"__TIFs5printFTGSaP__9separatorSS10terminatorSS_T_A0_", referenced from:
_main in main.swift.o
"__TIFs5printFTGSaP__9separatorSS10terminatorSS_T_A1_", referenced from:
_main in main.swift.o
"__TMSS", referenced from:
_main in main.swift.o
"__TTSg5P____TFs27_allocateUninitializedArrayurFBwTGSax_Bp_", referenced from:
_main in main.swift.o
"__TZvOs7Process11_unsafeArgvGSpGSpVs4Int8__", referenced from:
_main in main.swift.o
"__TZvOs7Process5_argcVs5Int32", referenced from:
_main in main.swift.o
"_globalinit_33_1BDF70FFC18749BAB495A73B459ED2F0_func5", referenced from:
_main in main.swift.o
"_globalinit_33_1BDF70FFC18749BAB495A73B459ED2F0_token5", referenced from:
_main in main.swift.o
ld: symbol(s) not found for architecture x86_64
<unknown>:0: error: build had 1 command failures
swift-build: exit(1): ["/Library/Developer/Toolchains/swift-2.2-SNAPSHOT-2015-12-01-a.xctoolchain/usr/bin/swift-build-tool", "-f", "/Users/kilian/Desktop/foo/.build/debug/foo.o/llbuild.yaml"]
Swift is Apple Swift version 2.2-dev (LLVM 46be9ff861, Clang 4deb154edc, Swift 778f82939c) Target: x86_64-apple-macosx10.9 as provided on swift.org.
The only troubleshooting info regarding this I can find online corresponds to Xcode and linking other external libraries. Any help here would be much appreciated.

Answer 1

I haven't tried the new open source Swift on my Mac yet, focusing on playing with it on Linux instead. However, one way something like this could happen on Linux is when Clang is not available. In that case swift REPL and swift as an interpreter work fine, but swiftc and swift build fail. Just out of curiosity you may want to try
swiftc main.swift
in your Sources directory. Google for xcode command line tools mac os x or a combination of those search terms. The following, for example, might help:
https://developer.apple.com/library/ios/technotes/tn2339/_index.html
To see if your command tools are available, try clang or gcc from the command line. If you get a message that there are no input files, then the tools are installed (maybe incorrectly). If you get some other error, then the tools aren't there, and that's a very likely cause of your problem.
Hope this helps.