update niv

Signed-off-by: Xe Iaso <me@christine.website>

1 files changed, 25 insertions, 2 deletions

diff --git a/nix/sources.nix b/nix/sources.nix
index b796fff..9a01c8a 100644
--- a/nix/sources.nix
+++ b/nix/sources.nix
@@ -31,8 +31,28 @@ let
           if spec ? branch then "refs/heads/${spec.branch}" else
             if spec ? tag then "refs/tags/${spec.tag}" else
               abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!";
+      submodules = if spec ? submodules then spec.submodules else false;
+      submoduleArg =
+        let
+          nixSupportsSubmodules = builtins.compareVersions builtins.nixVersion "2.4" >= 0;
+          emptyArgWithWarning =
+            if submodules == true
+            then
+              builtins.trace
+                (
+                  "The niv input \"${name}\" uses submodules "
+                  + "but your nix's (${builtins.nixVersion}) builtins.fetchGit "
+                  + "does not support them"
+                )
+                {}
+            else {};
+        in
+          if nixSupportsSubmodules
+          then { inherit submodules; }
+          else emptyArgWithWarning;
     in
-      builtins.fetchGit { url = spec.repo; inherit (spec) rev; inherit ref; };
+      builtins.fetchGit
+        ({ url = spec.repo; inherit (spec) rev; inherit ref; } // submoduleArg);
 
   fetch_local = spec: spec.path;
 
@@ -98,7 +118,10 @@ let
       saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
       ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
     in
-      if ersatz == "" then drv else ersatz;
+      if ersatz == "" then drv else
+        # this turns the string into an actual Nix path (for both absolute and
+        # relative paths)
+        if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + "/${ersatz}";
 
   # Ports of functions for older nix versions