Build Swift on Linux? Not just yet

I have carefully followed a number of “helpful” sets of instructions for building swift programs on Linux, and failed. Again and again.

Now, I have trawled the Swift.org site, and concluded two things:
1 Several of these “helpful” people have not actually followed their own instructions, which are mostly copy and paste from Swift.org … which leads to

2 The Swift Package Manager is a tool for managing the distribution of Swift code. It’s integrated with the Swift build system to automate the process of downloading, compiling, and linking dependencies.

The Package Manager will be released with Swift 3 and is currently only
available with the Swift 3 development snapshots.

My point 2) above is also copy and paste from Swift.org.