Fix #6114 - Calling setState inside getChildContext should warn

src/isomorphic/devtools/ReactInvalidSetStateWarningDevTool.js

@@ -0,0 +1,39 @@
+/**
+ * Copyright 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule ReactInvalidSetStateWarningDevTool
+ */
+
+'use strict';
+
+var warning = require('warning');
+
+if (__DEV__) {
+  var processingChildContext = false;
+
+  var warnInvalidSetState = function() {
+    warning(
+      !processingChildContext,
+      'setState(...): Cannot call setState() inside getChildContext()'
+    );
+  };
+}
+
+var ReactInvalidSetStateWarningDevTool = {
+  onBeginProcessingChildContext() {
+    processingChildContext = true;
+  },
+  onEndProcessingChildContext() {
+    processingChildContext = false;
+  },
+  onSetState() {
+    warnInvalidSetState();
+  },
+};
+
+module.exports = ReactInvalidSetStateWarningDevTool;