The "lifecycle" of stdenv genericBuild

[myme]

Might've already been covered, so I pardon that.

How about a little dive into the "lifecycle" and hooks of genericBuild. Perhaps writing a few very simple derivations where perhaps building isn't the main concern, but stuff like configuring, patching, substitutions etc. Then perhaps how certain toolchains might override phases and so on.

I see that The Nix Hour #7 [source filtering, writing package tests] touched on mkDerivation check phase, perhaps did cover this sufficiently.

[infinisil]

We looked at this more in Nix Hour 17, feel free to open more issues if you have other questions!