What targets are available for the swiftc -target and -target-cpu option?

Question

this question is about cross compilation.

What kind of different targets are available using the -target or -target-cpu option of the swift compiler? Where can I find an overview?

Is it only there to create iOS/watchOS apps or can I use it to create linux programs (regular x86-64 processor) on macOS?

I tried searching the github repository and found 'x86_64-unknown-linux-gnu' as a target. However when I try to compile a simple "hello world" program (swiftc -target x86_64-unknown-linux-gnu test.swift) I get this error:

<unknown>:0: error: unable to load standard library for target 'x86_64-unknown-linux-gnu'

Edit: I agree with CristiFati. The last part of this question is rather about how to properly include/reference the glibc (?!?).

Answer 1

If you look at Swift repository on Github (Exact location: swift/utils/swift_build_support/swift_build_support/targets.py) You will see all host targets at line 149-192 in target.py.

Supports:

def host_target():
    """
    Return the host target for the build machine, if it is one of
    the recognized targets. Otherwise, throw a NotImplementedError.
    """
    system = platform.system()
    machine = platform.machine()

    if system == 'Linux':
        if machine == 'x86_64':
            return StdlibDeploymentTarget.Linux.x86_64
        elif machine.startswith('armv7'):
            # linux-armv7* is canonicalized to 'linux-armv7'
            return StdlibDeploymentTarget.Linux.armv7
        elif machine.startswith('armv6'):
            # linux-armv6* is canonicalized to 'linux-armv6'
            return StdlibDeploymentTarget.Linux.armv6
        elif machine == 'aarch64':
            return StdlibDeploymentTarget.Linux.aarch64
        elif machine == 'ppc64':
            return StdlibDeploymentTarget.Linux.powerpc64
        elif machine == 'ppc64le':
            return StdlibDeploymentTarget.Linux.powerpc64le
        elif machine == 's390x':
            return StdlibDeploymentTarget.Linux.s390x

    elif system == 'Darwin':
        if machine == 'x86_64':
            return StdlibDeploymentTarget.OSX.x86_64

    elif system == 'FreeBSD':
        if machine == 'amd64':
            return StdlibDeploymentTarget.FreeBSD.x86_64

    elif system == 'CYGWIN_NT-10.0':
        if machine == 'x86_64':
            return StdlibDeploymentTarget.Cygwin.x86_64

    elif system == 'Windows':
        if machine == "AMD64":
            return StdlibDeploymentTarget.Windows.x86_64

    raise NotImplementedError('System "%s" with architecture "%s" is not '
                              'supported' % (system, machine))