Fix nixos-option

In particular, it no longer produces an "infinite recursion" error
when run with no arguments.

lib/modules.nix

@@ -160,6 +160,7 @@ rec {
       value = (opt.apply or id) merged;
     in opt //
       { value = addErrorContext "while evaluating the option `${showOption loc}':" value;
+        files = map (def: def.file) defs;
         definitions = map (def: def.value) defsFinal;
         isDefined = defsFinal != [];
       };

nixos/default.nix

@@ -9,7 +9,7 @@ let
     modules = [ configuration ];
   };
 
-  inherit (eval) config pkgs;
+  inherit (eval) pkgs;
 
   # This is for `nixos-rebuild build-vm'.
   vmConfig = (import ./lib/eval-config.nix {
@@ -30,9 +30,9 @@ let
 in
 
 {
-  inherit eval config;
+  inherit (eval) config options;
 
-  system = config.system.build.toplevel;
+  system = eval.config.system.build.toplevel;
 
   vm = vmConfig.system.build.vm;
 

nixos/lib/eval-config.nix

@@ -16,14 +16,11 @@ rec {
 
   # Merge the option definitions in all modules, forming the full
   # system configuration.
-  systemModule =
-    pkgs.lib.evalModules {
-      modules = modules ++ baseModules;
-      args = extraArgs;
-      inherit check;
-    };
-
-  config = systemModule.config;
+  inherit (pkgs.lib.evalModules {
+    modules = modules ++ baseModules;
+    args = extraArgs;
+    inherit check;
+  }) config options;
 
   # These are the extra arguments passed to every module.  In
   # particular, Nixpkgs is passed through the "pkgs" argument.

nixos/modules/installer/tools/nixos-option.sh

@@ -1,5 +1,7 @@
 #! @shell@ -e
 
+# FIXME: rewrite this in a more suitable language.
+
 usage () {
     exec man nixos-option
     exit 1
@@ -90,24 +92,25 @@ evalNix(){
 }
 
 evalAttr(){
-  local prefix=$1
-  local suffix=$2
-  local strict=$3
+  local prefix="$1"
+  local strict="$2"
+  local suffix="$3"
   echo "(import <nixos> {}).$prefix${option:+.$option}${suffix:+.$suffix}" |
     evalNix ${strict:+--strict}
 }
 
 evalOpt(){
-  evalAttr "eval.options" "$@"
+  evalAttr "options" "" "$@"
 }
 
 evalCfg(){
-  evalAttr "config" "$@"
+  local strict="$1"
+  evalAttr "config" "$strict"
 }
 
 findSources(){
   local suffix=$1
-  echo "builtins.map (f: f.source) (import <nixos> {}).eval.options${option:+.$option}.$suffix" |
+  echo "(import <nixos> {}).options${option:+.$option}.$suffix" |
     evalNix --strict
 }
 
@@ -143,7 +146,7 @@ let
   nixos = import <nixos> {};
   nixpkgs = import <nixpkgs> {};
   sources = builtins.map (f: f.source);
-  opt = reach nixos.eval.options;
+  opt = reach nixos.options;
   cfg = reach nixos.config;
 in
 
@@ -186,7 +189,7 @@ EOF
 fi
 
 if test "$(evalOpt "_type" 2> /dev/null)" = '"option"'; then
-  $value && evalCfg;
+  $value && evalCfg 1
 
   if $desc; then
     $value && echo;
@@ -212,14 +215,14 @@ if test "$(evalOpt "_type" 2> /dev/null)" = '"option"'; then
     nixMap printPath "$(findSources "declarations")"
     echo ""
     echo "Defined by:"
-    nixMap printPath "$(findSources "definitions")"
+    nixMap printPath "$(findSources "files")"
     echo ""
   fi
 
 else
   # echo 1>&2 "Warning: This value is not an option."
 
-  result=$(evalCfg)
+  result=$(evalCfg "")
   if names=$(attrNames "$result" 2> /dev/null); then
     echo 1>&2 "This attribute set contains:"
     escapeQuotes () { eval echo "$1"; }