From 1292e741ff9d9e71bde6f4e7aacc8ee442ee2cfc Mon Sep 17 00:00:00 2001
From: Ary Borenszweig <asterite@gmail.com>
Date: Fri, 17 Jan 2020 17:21:40 -0300
Subject: [PATCH] Compiler: check typeof dependencies before cleanup (#8695)

---
 spec/compiler/semantic/block_spec.cr                 | 11 +++++++++++
 src/compiler/crystal/semantic/cleanup_transformer.cr |  5 ++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/spec/compiler/semantic/block_spec.cr b/spec/compiler/semantic/block_spec.cr
index ff56dc1b08e0..8d51198aac10 100644
--- a/spec/compiler/semantic/block_spec.cr
+++ b/spec/compiler/semantic/block_spec.cr
@@ -1432,4 +1432,15 @@ describe "Block inference" do
       Node.new.sum
       )) { int32 }
   end
+
+  it "doesn't crash on cleaning up typeof node without dependencies (#8669)" do
+    semantic(%(
+      def foo(&)
+      end
+
+      foo do
+        typeof(bar)
+      end
+      ))
+  end
 end
diff --git a/src/compiler/crystal/semantic/cleanup_transformer.cr b/src/compiler/crystal/semantic/cleanup_transformer.cr
index 267cceb6b6d0..bff52a8cbecd 100644
--- a/src/compiler/crystal/semantic/cleanup_transformer.cr
+++ b/src/compiler/crystal/semantic/cleanup_transformer.cr
@@ -783,7 +783,10 @@ module Crystal
       node = super
 
       unless node.type?
-        node.unbind_from node.dependencies
+        if dependencies = node.dependencies?
+          node.unbind_from node.dependencies
+        end
+
         node.bind_to node.expressions
       end