[Nix-dev] Expression for run time for build environment closures?

[Tyson Whitehead]

On Tuesday, June 13, 2017 5:28:01 PM EDT Tyson Whitehead wrote:
> Is there any easy way to do this sort of thing already?  Generating and compiling code on the fly seems to be a popular thing to do at the moment (firedrake is another python example) so I can see this sort of thing would be useful beyond just theano.

I came up with following

let
  wrapped = command: buildInputs:
    runCommandCC "${command}-wrapped" { inherit buildInputs; } ''
      cat > "$out" <<EOF
      #!$(type -p bash)
      $(declare -xp | sed -e '/^[^=]\+="\('"''${NIX_STORE//\//\\/}"'\|[^\/]\)/!d')
      $(type -p ${command}) "\$@"
      EOF
      chmod +x "$out"
    '';
in
  wrapped "gcc" [ ncurses ] 

This creates the following sort of shell script file

#!/nix/store/010yd8jls8w4vcnql4zhjbnyp2yay5pl-bash-4.4-p5/bin/bash
declare -x CC="gcc"
declare -x CONFIG_SHELL="/nix/store/010yd8jls8w4vcnql4zhjbnyp2yay5pl-bash-4.4-p5/bin/bash"
declare -x CXX="g++"
declare -x NIX_BUILD_CORES="8"
declare -x NIX_CC="/nix/store/wgvrkijby0awhqkyfkj0qp9cc4921hd9-gcc-wrapper-5.4.0"
declare -x NIX_CFLAGS_COMPILE=" -isystem /nix/store/zsf6vd6q048116rypzi121kmx1565g92-ncurses-6.0-dev/include"
declare -x NIX_ENFORCE_NO_NATIVE="1"
declare -x NIX_ENFORCE_PURITY="1"
declare -x NIX_INDENT_MAKE="1"
declare -x NIX_LDFLAGS="-rpath /nix/store/7fr5dwl7pmbqjbq4286y6xmwx2bs6pbd-g++-wrapped/lib64 -rpath /nix/store/7fr5dwl7pmbqjbq4286y6xmwx2bs6pbd-g++-wrapped/lib  -L/nix/store/zsf6vd6q048116$
declare -x NIX_STORE="/nix/store"
declare -x PATH="/nix/store/zsf6vd6q048116rypzi121kmx1565g92-ncurses-6.0-dev/bin:/nix/store/adcj4hwyqnzri00vzjvm9npxncjjmxa2-ncurses-6.0/bin:/nix/store/xyw9r56nwy463549dl7l9bwlvqii5ysn-pat$
declare -x SHELL="/nix/store/010yd8jls8w4vcnql4zhjbnyp2yay5pl-bash-4.4-p5/bin/bash"
declare -x SHLVL="1"
declare -x SOURCE_DATE_EPOCH="1"
declare -x TZ="UTC"
declare -x _PATH="/nix/store/zsf6vd6q048116rypzi121kmx1565g92-ncurses-6.0-dev/bin:/nix/store/adcj4hwyqnzri00vzjvm9npxncjjmxa2-ncurses-6.0/bin:/nix/store/xyw9r56nwy463549dl7l9bwlvqii5ysn-pa$
declare -x buildInputs=""
declare -x builder="/nix/store/010yd8jls8w4vcnql4zhjbnyp2yay5pl-bash-4.4-p5/bin/bash"
declare -x name="g++-wrapped"
declare -x nativeBuildInputs="/nix/store/zsf6vd6q048116rypzi121kmx1565g92-ncurses-6.0-dev"
declare -x out="/nix/store/7fr5dwl7pmbqjbq4286y6xmwx2bs6pbd-g++-wrapped"
declare -x passAsFile="buildCommand"
declare -x propagatedBuildInputs=""
declare -x propagatedNativeBuildInputs=""
declare -x shell="/nix/store/010yd8jls8w4vcnql4zhjbnyp2yay5pl-bash-4.4-p5/bin/bash"
declare -x stdenv="/nix/store/nmzimmm6awzjl8czr17c8fmrdikhw0ma-stdenv"
declare -x system="x86_64-linux"
/nix/store/wgvrkijby0awhqkyfkj0qp9cc4921hd9-gcc-wrapper-5.4.0/bin/g++ "$@"

Cheers!  -Tyson