I am aware of the syntax and its meaning. I specified "meaningless" not because the syntax is meaningless ( if it was the compiler would issue an error about the syntax itself ) but because the practical use of specifying 'const' in either situation is meaningless IMO. You are getting a copy of some X. Why would you practically specify that this copied value cannot be changed ? I do not see a practical programming reason for doing anything that way despite your correctly formed examples above.
See item 21 'use const whenever possible 'of 'Effective C++', second edition. It is more to protect the programmer for accidental modifying temp objects which is probably a bug. With move ctor's there is actually a use case of modifying / stealing temp objects.