From 1db8092f15a81b1475e8785c080b17f53780fa34 Mon Sep 17 00:00:00 2001
From: Neil Fraser <fraser@google.com>
Date: Sun, 29 May 2016 14:53:29 -0700
Subject: [PATCH] Do not allow shadow blocks to have non-shadow children.

---
 core/connection.js | 18 ++++++++++++++----
 core/xml.js        |  6 ++++++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/core/connection.js b/core/connection.js
index c52280464..77da88b43 100644
--- a/core/connection.js
+++ b/core/connection.js
@@ -62,6 +62,7 @@ Blockly.Connection.REASON_WRONG_TYPE = 2;
 Blockly.Connection.REASON_TARGET_NULL = 3;
 Blockly.Connection.REASON_CHECKS_FAILED = 4;
 Blockly.Connection.REASON_DIFFERENT_WORKSPACES = 5;
+Blockly.Connection.REASON_SHADOW_PARENT = 6;
 
 /**
  * Connection this connection connects to.  Null if not connected.
@@ -283,18 +284,25 @@ Blockly.Connection.prototype.isConnected = function() {
  * @private
  */
 Blockly.Connection.prototype.canConnectWithReason_ = function(target) {
+  if (this.isSuperior()) {
+    var blockA = this.sourceBlock_;
+    var blockB = target.getSourceBlock();
+  } else {
+    var blockB = this.sourceBlock_;
+    var blockA = target.getSourceBlock();
+  }
   if (!target) {
     return Blockly.Connection.REASON_TARGET_NULL;
-  } else if (this.sourceBlock_ &&
-      target.getSourceBlock() == this.sourceBlock_) {
+  } else if (blockA && blockA == blockB) {
     return Blockly.Connection.REASON_SELF_CONNECTION;
   } else if (target.type != Blockly.OPPOSITE_TYPE[this.type]) {
     return Blockly.Connection.REASON_WRONG_TYPE;
-  } else if (this.sourceBlock_ && target.getSourceBlock() &&
-      this.sourceBlock_.workspace !== target.getSourceBlock().workspace) {
+  } else if (blockA && blockB && blockA.workspace !== blockB.workspace) {
     return Blockly.Connection.REASON_DIFFERENT_WORKSPACES;
   } else if (!this.checkType_(target)) {
     return Blockly.Connection.REASON_CHECKS_FAILED;
+  } else if (blockA.isShadow() && !blockB.isShadow()) {
+    return Blockly.Connection.REASON_SHADOW_PARENT;
   }
   return Blockly.Connection.CAN_CONNECT;
 };
@@ -321,6 +329,8 @@ Blockly.Connection.prototype.checkConnection_ = function(target) {
       throw 'Target connection is null.';
     case Blockly.Connection.REASON_CHECKS_FAILED:
       throw 'Connection checks failed.';
+    case Blockly.Connection.REASON_SHADOW_PARENT:
+      throw 'Connecting non-shadow to shadow block.';
     default:
       throw 'Unknown connection failure: this should never happen!';
   }
diff --git a/core/xml.js b/core/xml.js
index 07ac7b8e4..48cef7216 100644
--- a/core/xml.js
+++ b/core/xml.js
@@ -521,6 +521,12 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
     block.setCollapsed(collapsed == 'true');
   }
   if (xmlBlock.nodeName.toLowerCase() == 'shadow') {
+    // Ensure all children are also shadows.
+    var children = block.getChildren();
+    for (var i = 0, child; child = children[i]; i++) {
+      goog.asserts.assert(child.isShadow(),
+                          'Shadow block not allowed non-shadow child.');
+    }
     block.setShadow(true);
   }
   // Give the block a chance to clean up any initial inputs.