Warns when mutated props are passed.

src/renderers/shared/reconciler/ReactCompositeComponent.js

@@ -27,6 +27,7 @@ var emptyObject = require('emptyObject');
 var invariant = require('invariant');
 var shouldUpdateReactComponent = require('shouldUpdateReactComponent');
 var warning = require('warning');
+var shallowEqual = require('shallowEqual');
 
 function getDeclarationErrorAddendum(component) {
   var owner = component._currentElement._owner || null;
@@ -195,6 +196,22 @@ var ReactCompositeComponentMixin = {
           Component.displayName || Component.name || 'Component'
         );
       }
+
+      var instPropsNotReactElements = !ReactElement.isValidElement(inst.props);
+      var publicPropsNotReactElements = !ReactElement.isValidElement(publicProps);
+      var propsMutated = !shallowEqual(inst.props || {}, publicProps);
+      var componentName = Component.displayName || Component.name ||
+            'Component';
+
+      warning(
+        !instPropsNotReactElements ||
+          !publicPropsNotReactElements ||
+          componentName === 'StatelessComponent' ||
+          !propsMutated,
+        '%s(...): When calling super() in `%s`, make sure to pass ' +
+          'up the same props that your component\'s constructor was passed.',
+        componentName, componentName
+      );
     }
 
     // These should be set up in the constructor, but as a convenience for

src/renderers/shared/reconciler/__tests__/ReactCompositeComponent-test.js

@@ -1241,4 +1241,31 @@ describe('ReactCompositeComponent', function() {
 
   });
 
+  it('should warn when mutated props are passed', function() {
+
+    var container = document.createElement('div');
+
+    class Foo extends React.Component {
+      constructor(props) {
+        var _props = { idx: props.idx + '!' };
+        super(_props);
+      }
+
+      render() {
+        return <span />;
+      }
+    }
+
+    expect(console.error.calls.length).toBe(0);
+
+    ReactDOM.render(<Foo idx="qwe" />, container);
+
+    expect(console.error.calls.length).toBe(1);
+    expect(console.error.argsForCall[0][0]).toContain(
+      'Foo(...): When calling super() in `Foo`, make sure to pass ' +
+        'up the same props that your component\'s constructor was passed.'
+    );
+
+  });
+
 });