Add inputDerivation to enable binary caching

nix/mkNakedShell.nix

@@ -26,36 +26,62 @@ in
 , meta ? { }
 , passthru ? { }
 }:
-(derivation {
-  inherit name system;
-
-  # `nix develop` actually checks and uses builder. And it must be bash.
-  builder = bashPath;
-
-  # Bring in the dependencies on `nix-build`
-  args = [ "-ec" "${coreutils}/bin/ln -s ${profile} $out; exit 0" ];
-
-  # $stdenv/setup is loaded by nix-shell during startup.
-  # https://github.com/nixos/nix/blob/377345e26f1ac4bbc87bb21debcc52a1d03230aa/src/nix-build/nix-build.cc#L429-L432
-  stdenv = stdenv;
-
-  # The shellHook is loaded directly by `nix develop`. But nix-shell
-  # requires that other trampoline.
-  shellHook = ''
-    # Remove all the unnecessary noise that is set by the build env
-    unset NIX_BUILD_TOP NIX_BUILD_CORES NIX_STORE
-    unset TEMP TEMPDIR TMP TMPDIR
-    # $name variable is preserved to keep it compatible with pure shell https://github.com/sindresorhus/pure/blob/47c0c881f0e7cfdb5eaccd335f52ad17b897c060/pure.zsh#L235
-    unset builder out shellHook stdenv system
-    # Flakes stuff
-    unset dontAddDisableDepTrack outputs
-
-    # For `nix develop`. We get /noshell on Linux and /sbin/nologin on macOS.
-    if [[ "$SHELL" == "/noshell" || "$SHELL" == "/sbin/nologin" ]]; then
-      export SHELL=${bashPath}
-    fi
-
-    # Load the environment
-    source "${profile}/env.bash"
-  '';
-}) // { inherit meta passthru; } // passthru
+let
+  derivationArg = {
+    inherit name system;
+
+    # `nix develop` actually checks and uses builder. And it must be bash.
+    builder = bashPath;
+
+    # Bring in the dependencies on `nix-build`
+    args = [ "-ec" "${coreutils}/bin/ln -s ${profile} $out; exit 0" ];
+
+    # $stdenv/setup is loaded by nix-shell during startup.
+    # https://github.com/nixos/nix/blob/377345e26f1ac4bbc87bb21debcc52a1d03230aa/src/nix-build/nix-build.cc#L429-L432
+    stdenv = stdenv;
+
+    # The shellHook is loaded directly by `nix develop`. But nix-shell
+    # requires that other trampoline.
+    shellHook = ''
+      # Remove all the unnecessary noise that is set by the build env
+      unset NIX_BUILD_TOP NIX_BUILD_CORES NIX_STORE
+      unset TEMP TEMPDIR TMP TMPDIR
+      # $name variable is preserved to keep it compatible with pure shell https://github.com/sindresorhus/pure/blob/47c0c881f0e7cfdb5eaccd335f52ad17b897c060/pure.zsh#L235
+      unset builder out shellHook stdenv system
+      # Flakes stuff
+      unset dontAddDisableDepTrack outputs
+
+      # For `nix develop`. We get /noshell on Linux and /sbin/nologin on macOS.
+      if [[ "$SHELL" == "/noshell" || "$SHELL" == "/sbin/nologin" ]]; then
+        export SHELL=${bashPath}
+      fi
+
+      # Load the environment
+      source "${profile}/env.bash"
+    '';
+  };
+in
+  (derivation derivationArg) // {
+    inherit meta passthru;
+
+    # https://github.com/NixOS/nixpkgs/blob/41f7e338216fd7f5e57817c4f8e148d42fb88b24/pkgs/stdenv/generic/make-derivation.nix#L486-L504
+    inputDerivation = derivation (derivationArg // {
+      # Add a name in case the original drv didn't have one
+      name = derivationArg.name or "inputDerivation";
+      # This always only has one output
+      outputs = [ "out" ];
+
+      # Propagate the original builder and arguments, since we override
+      # them and they might contain references to build inputs
+      _derivation_original_builder = derivationArg.builder;
+      _derivation_original_args = derivationArg.args;
+
+      builder = bashPath;
+      # The bash builtin `export` dumps all current environment variables,
+      # which is where all build input references end up (e.g. $PATH for
+      # binaries). By writing this to $out, Nix can find and register
+      # them as runtime dependencies (since Nix greps for store paths
+      # through $out to find them)
+      args = [ "-c" "export > $out" ];
+    });
+  } // passthru