Targeting particular x86_64 generation (haswell/ivybridge/skylake/...)

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@volth Thank you so much! Learning to use NixOS is a fun exercise (that I’m falling in love with).

I’m still stumped on overriding default makeopts like CFLAGS, CXXFLAGS, etc. With Gentoo it is so easy… I found this in the nixpkgs manual:

makeFlagsArray

A shell array containing additional arguments passed to make . You must use this instead of makeFlags if the arguments contain spaces, e.g.

preBuild = 
'' makeFlagsArray+=(CFLAGS="-O0 -g" LDFLAGS="-lfoo -lbar")
 '';

Note that shell arrays cannot be passed through environment variables, so you cannot set makeFlagsArray in a derivation attribute (because those are passed through environment variables): you have to define them in shell code.

So how exactly can I set these for every package? It feels like this should be as easy as changing gcc.arch or gcc.tune!

Edit: Could I do it like this (copied from a Nix cheatsheet site)?
stdenv.userHook = '' NIX_CFLAGS_COMPILE+=" -march=native" '';

Or is something like this required and an overridden stdenv?