Pass a flake to itself as "self"

flake.nix

@@ -3,13 +3,15 @@
 
   description = "The purely functional package manager";
 
-  requires = [ flake:nixpkgs ];
+  epoch = 2019;
 
-  provides = flakes: rec {
+  requires = [ "nixpkgs" ];
+
+  provides = deps: rec {
 
     hydraJobs = import ./release.nix {
-      nix = flakes.nix; # => flakes.self?
-      nixpkgs = flakes.nixpkgs;
+      nix = deps.self;
+      nixpkgs = deps.nixpkgs;
     };
 
     packages.nix = hydraJobs.build.x86_64-linux;

src/libexpr/primops/flake.cc

@@ -441,6 +441,8 @@ void callFlake(EvalState & state, const Dependencies & flake, Value & v)
     auto vProvides = state.allocAttr(v, state.symbols.create("provides"));
     mkApp(*vProvides, *flake.flake.vProvides, v);
 
+    v.attrs->push_back(Attr(state.symbols.create("self"), &v));
+
     v.attrs->sort();
 }