Merge pull request tweag#94 from tweag/repository-file-deps

Fix nix_file_deps on nixpkgs_local_repository

WORKSPACE

@@ -20,6 +20,7 @@ nixpkgs_git_repository(
 nixpkgs_local_repository(
     name = "nixpkgs",
     nix_file = "//:nixpkgs.nix",
+    nix_file_deps = ["//:nixpkgs.json"],
 )
 
 nixpkgs_package(
@@ -39,6 +40,7 @@ nixpkgs_package(
     nix_file_content = "let pkgs = import <nixpkgs> { config = {}; overlays = []; }; in pkgs.hello",
     # Deliberately not @nixpkgs, to test whether explict file works.
     repositories = {"nixpkgs": "//:nixpkgs.nix"},
+    nix_file_deps = ["//:nixpkgs.json"],
 )
 
 nixpkgs_package(
@@ -101,6 +103,7 @@ nixpkgs_package(
     attribute_path = "hello",
     nix_file = "//tests:relative_imports.nix",
     nix_file_deps = [
+        "//:nixpkgs.json",
         "//:nixpkgs.nix",
         "//tests:relative_imports/nixpkgs.nix",
     ],

nixpkgs.json

@@ -0,0 +1,8 @@
+{
+  "owner": "NixOS",
+  "repo": "nixpkgs-channels",
+  "branch": "nixpkgs-unstable",
+  "rev": "0620e0fdbf4d79df771afd28f741b2159f381d2b",
+  "sha256": "046l2c83s568c306hnm8nfdpdhmgnbzgid354hr7p0khq3jx3lhf"
+}
+

nixpkgs.nix

@@ -1,10 +1,9 @@
 let
   # nixpkgs-unstable as of 2019-04-25
-  nixpkgsRev = "0620e0fdbf4";
-  nixpkgsSha256 = "046l2c83s568c306hnm8nfdpdhmgnbzgid354hr7p0khq3jx3lhf";
+  spec = builtins.fromJSON (builtins.readFile ./nixpkgs.json);
   nixpkgs = fetchTarball {
-    url = "https://github.com/nixos/nixpkgs/archive/${nixpkgsRev}.tar.gz";
-    sha256 = nixpkgsSha256;
+    url = "https://github.com/${spec.owner}/${spec.repo}/archive/${spec.rev}.tar.gz";
+    sha256 = spec.sha256;
   };
 in
 import nixpkgs

nixpkgs/nixpkgs.bzl

@@ -38,12 +38,14 @@ def _nixpkgs_local_repository_impl(repository_ctx):
         )
         target = repository_ctx.path("default.nix")
     else:
-        target = repository_ctx.path(repository_ctx.attr.nix_file)
-        _cp(repository_ctx, target, target.basename)
+        target = _cp(repository_ctx, repository_ctx.attr.nix_file)
+
+    for dep in repository_ctx.attr.nix_file_deps:
+        _cp(repository_ctx, dep)
 
     # Make "@nixpkgs" (syntactic sugar for "@nixpkgs//:nixpkgs") a valid
     # label for the target Nix file.
-    repository_ctx.symlink(target.basename, repository_ctx.name)
+    repository_ctx.symlink(target, repository_ctx.name)
 
 nixpkgs_local_repository = repository_rule(
     implementation = _nixpkgs_local_repository_impl,