hphpc-docker

Getting old build tools to work is really awesome. I went through a similar process getting an old version of HPHPc (the PHP-to-c compiler precursor to HHVM) to work[1]. I found Docker to be incredibly invaluable for doing this in a reproducible way, especially when the system state needed to be changed in complex ways or dependencies needed to be tweaked. A small example is that the test cases only work right if English, German, Finnish and French locales are available and if the system timezone is set to "America/Los_Angeles". [1]: https://github.com/allanlw/hphpc-docker

If you want to use an existing toolchain, you could use HPHPc (the predecessor to HHVM, which transpiled PHP to C code) and emscripten to translate from C to Javascript. It would probably require some mucking around at the emscripten layer though to get all the packages linking properly, because HPHPc has a non-trivial number of (non-optional) runtime deps for supporting all of the various php modules. You should just be able to compile them separately with emscripten into a prefix (e.g. don't use emscripten ports, which I've had a terrible time with) but YMMV. I dockerized a working version of HPHPc (which is quite difficult to set up due to bitrot) at https://github.com/allanlw/hphpc-docker if you want to play around with the compiler. I might try to take a shot at passing it through emscripten later.