From b9588ddf03982ec81244291ca59c17f8da4cc0e8 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Mon, 19 Dec 2016 13:01:18 +0000
Subject: [PATCH] firmware: don't crash on artiq_compile'd kernels (fixes
 #641).

---
 artiq/firmware/libksupport/lib.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/artiq/firmware/libksupport/lib.rs b/artiq/firmware/libksupport/lib.rs
index 4543bce4c..4248e1a2d 100644
--- a/artiq/firmware/libksupport/lib.rs
+++ b/artiq/firmware/libksupport/lib.rs
@@ -272,6 +272,9 @@ unsafe fn attribute_writeback(typeinfo: *const ()) {
         objects:    *const *const ()
     }
 
+    // artiq_compile'd kernels don't include type information
+    if typeinfo.is_null() { return }
+
     let mut tys = typeinfo as *const *const Type;
     while !(*tys).is_null() {
         let ty = *tys;