top-level: Lay the groundwork for `{build,host,target}Platform`

The long term goal is a big replace:
  { inherit system platform; } => buildPlatform
  crossSystem => hostPlatform
  stdenv.cross => targetPlatform
And additionally making sure each is defined even when not cross compiling.

This commit refactors the bootstrapping code along that vision, but leaves
the old identifiers with their null semantics in place so packages can be
modernized incrementally.

1 files changed, 6 insertions, 3 deletions

diff --git a/pkgs/stdenv/custom/default.nix b/pkgs/stdenv/custom/default.nix
index d7e9bf53bed1..d5dc977b37a7 100644
--- a/pkgs/stdenv/custom/default.nix
+++ b/pkgs/stdenv/custom/default.nix
@@ -1,12 +1,12 @@
 { lib
-, system, platform, crossSystem, config, overlays
+, localSystem, crossSystem, config, overlays
 }:
 
 assert crossSystem == null;
 
 let
   bootStages = import ../. {
-    inherit lib system platform crossSystem overlays;
+    inherit lib localSystem crossSystem overlays;
     # Remove config.replaceStdenv to ensure termination.
     config = builtins.removeAttrs config [ "replaceStdenv" ];
   };
@@ -15,7 +15,10 @@ in bootStages ++ [
 
   # Additional stage, built using custom stdenv
   (vanillaPackages: {
-    inherit system platform crossSystem config overlays;
+    buildPlatform = localSystem;
+    hostPlatform = localSystem;
+    targetPlatform = localSystem;
+    inherit config overlays;
     stdenv = config.replaceStdenv { pkgs = vanillaPackages; };
   })