From 3d115a28fd5c8cec43d773c7cbad5f9398e0ebbb Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Wed, 10 Jun 2020 11:24:35 +0200
Subject: [PATCH] Fix documentation example.

---
 docs/types/reference-types.rst | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/docs/types/reference-types.rst b/docs/types/reference-types.rst
index 6283eaa0e..5bd242f06 100644
--- a/docs/types/reference-types.rst
+++ b/docs/types/reference-types.rst
@@ -430,7 +430,13 @@ Array slices are useful to ABI-decode secondary data passed in function paramete
         /// Forward call to "setOwner(address)" that is implemented by client
         /// after doing basic validation on the address argument.
         function forward(bytes calldata _payload) external {
-            bytes4 sig = abi.decode(_payload[:4], (bytes4));
+            // Since ABI decoding requires padded data, we cannot
+            // use abi.decode(_payload[:4], (bytes4)).
+            bytes4 sig =
+                _payload[0] |
+                (bytes4(_payload[1]) >> 8) |
+                (bytes4(_payload[2]) >> 16) |
+                (bytes4(_payload[3]) >> 24);
             if (sig == bytes4(keccak256("setOwner(address)"))) {
                 address owner = abi.decode(_payload[4:], (address));
                 require(owner != address(0), "Address of owner cannot be zero.");