top-level: Stop exposing all stdenvs

pkgs/stdenv/cross/default.nix

@@ -8,7 +8,7 @@ rec {
   };
   vanillaStdenv = (import ../. (args // argClobber // {
     allPackages = args: allPackages (argClobber // args);
-  })).stdenv // {
+  })) // {
     # Needed elsewhere as a hacky way to pass the target
     cross = crossSystem;
   };

pkgs/stdenv/custom/default.nix

@@ -1,10 +1,10 @@
 { system, allPackages, platform, crossSystem, config, ... } @ args:
 
 rec {
-  vanillaStdenv = (import ../. (args // {
+  vanillaStdenv = import ../. (args // {
     # Remove config.replaceStdenv to ensure termination.
     config = builtins.removeAttrs config [ "replaceStdenv" ];
-  })).stdenv;
+  });
 
   buildPackages = allPackages {
     # It's OK to change the built-time dependencies

pkgs/stdenv/default.nix

@@ -8,7 +8,7 @@
 { system, allPackages ? import ../.., platform, config, crossSystem, lib }:
 
 
-rec {
+let
 
 
   # The native (i.e., impure) build environment.  This one uses the
@@ -43,7 +43,7 @@ rec {
   inherit (import ./custom { inherit system allPackages platform crossSystem config lib; }) stdenvCustom;
 
   # Select the appropriate stdenv for the platform `system'.
-  stdenv =
+in
     if crossSystem != null then
       if crossSystem.useiOSCross or false then stdenvCrossiOS
       else stdenvCross else
@@ -60,5 +60,4 @@ rec {
     if system == "i686-cygwin" then stdenvNative else
     if system == "x86_64-cygwin" then stdenvNative else
     if system == "x86_64-freebsd" then stdenvFreeBSD else
-    stdenvNative;
-}
+    stdenvNative

pkgs/top-level/stdenv.nix

@@ -1,12 +1,10 @@
 { system, bootStdenv, crossSystem, config, platform, lib, nixpkgsFun }:
 
 rec {
-  allStdenvs = import ../stdenv {
+  defaultStdenv = import ../stdenv {
     inherit system platform config crossSystem lib;
     allPackages = nixpkgsFun;
-  };
-
-  defaultStdenv = allStdenvs.stdenv // { inherit platform; };
+  } // { inherit platform; };
 
   stdenv =
     if bootStdenv != null