some packages have a hook like this or similar

preBuild = ''
  export XDG_CACHE_HOME="$(mktemp -d)"
'';

I have a flake with a devShells.default that uses inputsFrom to create a development environment for a package. If I use nix develop it drops me into a shell with a correct phase functions (buildPhase, etc.). However, if I use nix develop --build I get unexpected errors about no makefiles and if I use nix develop --command bash -c buildPhase bash complains about no such command buildPhase.

What do I need to do in my devShells.default so that either nix develop --build or nix develop --command bash -c buildPhase works? Thanks!

and you're just doing use flake in your .envrc?

what does your flake look like?

Yes

Right now like so

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
  };
  outputs = {nixpkgs, ...}: let
    system = "x86_64-linux";
    pkgs = import nixpkgs {
      inherit system;
      crossSystem = {
        config = "armv7l-linux-gnueabihf";
      };
    };
  in {
    devShells.${system}.default = import ./nix/shell.nix {inherit pkgs;};
  };
  nixConfig = {
    extraOptions = ''
      keep-outputs = true
      keep-derivations = true
    '';
  };
}

The shell.nix looks like so

{pkgs, ...}:
pkgs.mkShell {
  buildInputs = [
    pkgs.glibc
    pkgs.glibc.static
  ];

  makeFlags = [
    "CC=${pkgs.stdenv.cc.targetPrefix}cc"
    "CXX=${pkgs.stdenv.cc.targetPrefix}g++"
  ];
}