It's not whether "IP" laws apply; it's whether source code itself is in scope for patents. Source code is a description of an algorithm, which in principle is what the software patent is supposed to be providing anyway. Patents shouldn't be relevant here for the same reason they aren't relevant to what you write in e.g. a textbook on signal processing where you might find an exact description of how Shazam works.
Compiling and running that source code on your computer/as part of a wider system may violate a patent, but my impression was that patents are not relevant to the actual code. Are there test cases in the US around pure source distribution of a patented algorithm? Particularly post-Alice?
I wonder if the massive amount of open source software can now be used as elaborate 'prior art' in a way that basically invalidates any software patent that is awarded after the source had been made available?
I.e. if any algorithm was already implemented, in some variation, then the patent is not valid?
For example, for the infamous Amazon 'one click purchase', if a similar pattern was used, maybe a 'one click start vacuum cleaner robot', would it that patent then be invalid?