From 9ccd1c7e23ffb88ced79c76460b0aabc693a2abf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Soko=C5=82owski?= <jakub@status.im>
Date: Fri, 10 Jan 2025 16:04:40 +0100
Subject: [PATCH] assert submodules are available to Nix derivation
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This should result in a human-readable error when `?submodules=1#` is
not appended to the project URL as the README explains:
```
 > nix build '.'
       error: Unable to build without submodules. Append '?submodules=1#' to the URL.

 > nix build '.?submodules=1#'
```

Signed-off-by: Jakub Sokołowski <jakub@status.im>
---
 nix/default.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/nix/default.nix b/nix/default.nix
index 6e61e80c15..97d923987c 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -16,6 +16,10 @@
   ],
 }:
 
+# The 'or' is to handle src fallback to ../. which lack submodules attribue.
+assert pkgs.lib.assertMsg ((src.submodules or true) == true)
+  "Unable to build without submodules. Append '?submodules=1#' to the URI.";
+
 let
   inherit (pkgs) stdenv lib writeScriptBin callPackage;