From 794295b3f6ceea721c87c09af91e5f47d52c228f Mon Sep 17 00:00:00 2001
From: Stephan Dilly <dilly.stephan@gmail.com>
Date: Tue, 12 Nov 2019 00:56:48 +0100
Subject: [PATCH] Helper attributes in attribute macros

This little gotcha took me a while to figure out, maybe others will benefit from this addition swell
---
 src/procedural-macros.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/procedural-macros.md b/src/procedural-macros.md
index 2bd3706a2..d6ae363d6 100644
--- a/src/procedural-macros.md
+++ b/src/procedural-macros.md
@@ -273,6 +273,11 @@ fn invoke4() {}
 // out: item: "fn invoke4() {}"
 ```
 
+#### Attribute macro helper attributes
+
+Unlike for [Derive macros] helper attributes do not have to be marked explicitly.
+Since attribute macros can completely discard the input token stream filtering out custom `helper` attributes is entirely the job of the attribute macro.
+
 [Attribute macros]: #attribute-macros
 [Cargo's build scripts]: ../cargo/reference/build-scripts.html
 [Derive macros]: #derive-macros