This allows use you to get all drvs that your Nix expression
references. Output looks like this:

  $ nix-instantiate --include-ifd
  warning: you did not specify '--add-root'; the result might be removed by the garbage collector
  /nix/store/xvplw4i56ys3j1lk4bxnr8r4725rb6c8-bauer-1.5.0.drv
  /nix/store/nk7j41ldlq39lmmsg5v1mlwwwpnqnbgk-README.drv
  /nix/store/pp84r1z7j7aqqarbwkq55h5asy35rs15-package-list.drv

This can be piped put into nix-store to get all outputs needed:

  $ nix-store -qR --include-outputs $(nix-instantiate --include-ifd)
  /nix/store/00crwk6z71l36av0gspzi0z410h8fq1r-libXtst-1.2.3.tar.bz2
  /nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25b-default-builder.sh
  /nix/store/58y89v7rl254dc2cygcfd5wzhv0kjm4m-bash44-013.drv
  /nix/store/7c0yirypq720qgj2clyanqp3b18h1lj0-bison-3.4.2.tar.gz.drv
  /nix/store/b7irlwi2wjlx5aj1dghx4c8k3ax6m56q-busybox.drv
  /nix/store/c0sr4qdy8halrdrh5dpm7hj05c6hyssa-unpack-bootstrap-tools.sh
  /nix/store/drsdq2ca1q1dj1hd0r1w2hl4s0fak1vh-bootstrap-tools.tar.xz.drv
  /nix/store/bfil786fxmnjcwc7mqpm0mk4xnm2cphg-bootstrap-tools.drv
  ...

This print out all of the store paths referenced in the Nix
expression. Examples provided in --help.

This is useful with tools like cachix, and replace the previous usages
of:

  $ nix-store -qR --include-outputs $(nix-instantiate '<nixpkgs>' -A hello)

which now become:

  $ nix refs --build --run nixpkgs.hello

which can be piped into cachix like:

  $ nix refs --build --run nixpkgs.hello | cachix push my-cache

Related to cachix/cachix#52
and NixOS#3506

nix-instantiate is deprecated!

Both require --recursive. --build calculates all buildtime
dependencies of a path. --eval calculates all evaltime dependencies of
an expression.

Now used in nix/command.cc error

If we still have the .drv, it will be available in our database under
deriver. We can use that instead of requiring we actually received a
drvPath.

Co-authored-by: John Ericson <git@JohnEricson.me>

Even non-derivations are important to have in this output, so keep
them in our list.

This is more accurate since things like fileExists and readFile also
go through this.

Runtime deps aren’t always useful, especially in the case of creating
gc roots for eval deps. for instance:

  $ nix-store --add-result --indirect -r $(nix path-info --recursive --no-run --eval my-expression)

This could have some bad interactions with the eval cache. Once flakes
is merged, we can resolve those so that --eval will always reevaluate
the expression.