From a08c2392c480b04b6e159ca3ceec91048ee6758a Mon Sep 17 00:00:00 2001
From: Stephen von Takach <steve@vontaka.ch>
Date: Tue, 17 Nov 2020 15:12:44 +1100
Subject: [PATCH] feat: bitfield macro outside of a bitfield error message

to help simplify debugging with a less obscure error message
---
 shard.yml      | 2 +-
 src/bindata.cr | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/shard.yml b/shard.yml
index 0d8fca8..c48f95f 100644
--- a/shard.yml
+++ b/shard.yml
@@ -1,5 +1,5 @@
 name: bindata
-version: 1.8.0
+version: 1.8.1
 
 development_dependencies:
   ameba:
diff --git a/src/bindata.cr b/src/bindata.cr
index a7f70ee..d19480f 100644
--- a/src/bindata.cr
+++ b/src/bindata.cr
@@ -350,7 +350,8 @@ abstract class BinData
   end
 
   macro bits(size, name, value = nil, default = nil)
-    %field = @@bit_fields["{{KLASS_NAME[0]}}_{{INDEX[0]}}"]
+    %field = @@bit_fields["{{KLASS_NAME[0]}}_{{INDEX[0]}}"]?
+    raise "#{KLASS_NAME[0]}#{ '#' }{{name}} is not defined in a bitfield. Using bitfield macro outside of a bitfield" unless %field
     %field.bits({{size}}, {{name.id.stringify}})
 
     {% if size <= 8 %}