Merge pull request #3609 from RobbieFerguson/patch-1

Update Delegatecall Description in Docs

docs/units-and-global-variables.rst

@@ -168,6 +168,13 @@ For more information, see the section on :ref:`address`.
     to make safe Ether transfers, always check the return value of ``send``, use ``transfer`` or even better:
     Use a pattern where the recipient withdraws the money.
 
+.. note::
+   If storage variables are accessed via a low-level delegatecall, the storage layout of the two contracts
+   must align in order for the called contract to correctly access the storage variables of the calling contract by name.
+   This is of course not the case if storage pointers are passed as function arguments as in the case for
+   the high-level libraries.
+   
+    
 .. note::
     The use of ``callcode`` is discouraged and will be removed in the future.