Override default installed Mix with HEAD version?

I want to use a recent fix in Mix (specifically Another attempt at fixing opening in browser on Windows · hexpm/hex@dd9c62b · GitHub) before the next elixir release arrives. I’ve looked through my installation directories (.asdf/installs/elixir/current/ on linux and ~\scoop\apps\elixir\current\ on windows) and have confused myself. I’ve browsed and ripgrepped and can’t find the relevant source. I realise I don’t have a good handle on how the default packages work so wouldn’t be sure what to do even if I do find it. So some questions from the general to the specific:

  • is there a good general doc or description somewhere of how elixir packages relate to modules, and how module discovery and loading works? (in which case I might be able to answer the below questions myself).
  • what are the source files (in [installdir]/lib) used for? I’m guessing they’re not locally compiled, given the presence of the presumably preinstalled *.beam files in [installdir]/lib/**/ebin?
  • either way, can a preinstalled package be overriden locally? (eg. is there an equivalent of the order in a java classpath I can rely on, or can I edit and recompile one of the preinstalled modules in place?)
  • how would I do this (whatever ‘this’ may turn out to be) for the Mix.Tasks.Hex.Docs in the quoted commit?

Answers to any or all alike much appreciated!

Create a simbolic link in the install folder , that points to the git repo, I call mine “main” which is the name of the Elixir branch it is running on.

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After a bit of digging, the TLDR is just to delete my ~/.mix folder, and then reinstall the mix archive from HEAD with mix install github hexpm/hex. I hadn’t entirely grokked that the Mix.Tasks.Hex.Docs package isn’t part of the Elixir installation, but comes with Hex.

In case anyone else comes across this and wonders, here are my rube-ish answers to those of my own questions I’ve managed to answer myself (corrections/additions very welcome):

I haven’t found a single comprehensive source, but reading this Erlang doc (Erlang -- code), and playing around in iex with the :code functions was pretty enlightening.

Perhaps but I haven’t tried it as it turned out not to be relevant to my situation after all. There is of course a code path from which BEAM files are loaded, and you can add to it :code.add_paths/1 or via an $ERL_LIBS env var. In Erlang you can override anything other than the Kernel and StdLib modules, but I’m not sure about Elixir.

Remove the hex-installed archives from ~/.mix, and reinstall from the hexpm/hex github repo HEAD with mix archive.install.

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Thanks @eksperimental - it turns out I misdirected you, & the changes I wanted to bring in weren’t from the base Elixir installation.