From 49fe4299905e5066bf76bc1b53f3f7c153689334 Mon Sep 17 00:00:00 2001
From: Eric Bailey <eric@ericb.me>
Date: Thu, 30 Jan 2020 11:58:17 -0600
Subject: [PATCH] lfe: add message to OTP version assertion

---
 pkgs/development/interpreters/lfe/generic-builder.nix | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pkgs/development/interpreters/lfe/generic-builder.nix b/pkgs/development/interpreters/lfe/generic-builder.nix
index 6e74229e1e88..5df491e72d3a 100644
--- a/pkgs/development/interpreters/lfe/generic-builder.nix
+++ b/pkgs/development/interpreters/lfe/generic-builder.nix
@@ -9,7 +9,7 @@
 }:
 
 let
-  inherit (stdenv.lib) getVersion versionAtLeast versions;
+  inherit (stdenv.lib) assertMsg getVersion versionAtLeast versions;
 
   mainVersion = versions.major (getVersion erlang);
 
@@ -25,7 +25,9 @@ let
   };
 
 in
-assert versionAtLeast maximumOTPVersion mainVersion;
+assert (assertMsg (versionAtLeast maximumOTPVersion mainVersion)) ''
+  LFE ${version} is supported on OTP <=${maximumOTPVersion}, not ${mainVersion}.
+'';
 
 buildRebar3 {
   name = baseName;