From 577645d09fe5bae5f3a5244ba12e3ec13b488a6e Mon Sep 17 00:00:00 2001
From: Thiago Kenji Okada <thiagokokada@gmail.com>
Date: Mon, 25 Jan 2021 11:36:46 -0300
Subject: [PATCH] dart: add some assertions

---
 pkgs/development/interpreters/dart/default.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkgs/development/interpreters/dart/default.nix b/pkgs/development/interpreters/dart/default.nix
index cf92e723a612..5fb180201b96 100644
--- a/pkgs/development/interpreters/dart/default.nix
+++ b/pkgs/development/interpreters/dart/default.nix
@@ -9,6 +9,9 @@
     x86_64 = "x64";
     i686 = "ia32";
     aarch64 = "arm64";
+    # Make sure that if the user overrides version parameter they're
+    # also need to override sources, to avoid mistakes
+    version = "2.10.5";
   in
   {
     "${version}-x86_64-darwin" = fetchurl {
@@ -30,6 +33,9 @@
   }
 }:
 
+assert version != null && version != "";
+assert sources != null && (builtins.isAttrs sources);
+
 stdenv.mkDerivation {
   pname = "dart";
   inherit version;