Auto-overlay niv sources

This is somewhat experimental, the idea is automatically set the sources
from my niv pinned deps. It seems to work, so I'll keep at it and see if
I can improve it as issues come up.

1 files changed, 16 insertions, 0 deletions

diff --git a/nix/sources-overlay.nix b/nix/sources-overlay.nix
new file mode 100644
index 0000000..b19bb34
--- /dev/null
+++ b/nix/sources-overlay.nix
@@ -0,0 +1,16 @@
+_: pkgs:
+
+rec {
+  pinnedDeps = builtins.attrNames
+    (builtins.removeAttrs pkgs.sources ["__functor"]);
+  overridePinnedDeps = builder: pkgs.lib.genAttrs pinnedDeps builder;
+
+  # Modifies a derivation with our source and version, keeping old build
+  # rules. This will fail if build steps have changed, or if no build
+  # rules are available upstream..
+  overrideSource = name: pkgs.${name}.overrideAttrs (old: old // rec {
+    name = "${name}-${version}";
+    version = pkgs.sources.${name}.version or pkgs.sources.${name}.rev;
+    src = pkgs.sources.${name};
+  });
+}