Make flake input fetching lazy

As long as the flake input is locked, it is now only fetched when it
is evaluated (e.g. "nixpkgs" is fetched when
"inputs.nixpkgs.<something>" is evaluated).

This required adding an "id" attribute to the members of "inputs" in
lockfiles, e.g.

  "inputs": {
    "nixpkgs/release-19.03": {
      "id": "nixpkgs",
      "inputs": {},
      "narHash": "sha256-eYtxncIMFVmOHaHBtTdPGcs/AnJqKqA6tHCm0UmPYQU=",
      "nonFlakeInputs": {},
      "uri": "github:edolstra/nixpkgs/e9d5882bb861dc48f8d46960e7c820efdbe8f9c1"
    }
  }

because the flake ID needs to be known beforehand to construct the
"inputs" attrset.

Fixes #2913.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 8d6716391..d229c7512 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -136,6 +136,7 @@ static nlohmann::json nonFlakeToJson(const NonFlake & nonFlake)
     return j;
 }
 
+#if 0
 // FIXME: merge info CmdFlakeInfo?
 struct CmdFlakeDeps : FlakeCommand
 {
@@ -173,6 +174,7 @@ struct CmdFlakeDeps : FlakeCommand
         }
     }
 };
+#endif
 
 struct CmdFlakeUpdate : FlakeCommand
 {
@@ -232,6 +234,7 @@ struct CmdFlakeInfo : FlakeCommand, MixJSON
         if (json) {
             auto json = flakeToJson(flake);
 
+#if 0
             auto state = getEvalState();
 
             auto vFlake = state->allocValue();
@@ -254,6 +257,7 @@ struct CmdFlakeInfo : FlakeCommand, MixJSON
                 });
 
             json["outputs"] = std::move(outputs);
+#endif
 
             std::cout << json.dump() << std::endl;
         } else
@@ -518,7 +522,7 @@ struct CmdFlake : virtual MultiCommand, virtual Command
             , make_ref<CmdFlakeUpdate>()
             , make_ref<CmdFlakeInfo>()
             , make_ref<CmdFlakeCheck>()
-            , make_ref<CmdFlakeDeps>()
+            //, make_ref<CmdFlakeDeps>()
             , make_ref<CmdFlakeAdd>()
             , make_ref<CmdFlakeRemove>()
             , make_ref<CmdFlakePin>()