re PR c++/24560 ("insufficient contextual information to determine type" is not a helpful error message)

	PR c++/24560
	* parser.c (cp_parser_postfix_dot_deref_expression): Improve error
	message for use of overloaded functions on LHS of "." operator.
	PR c++/24560
	* g++.dg/parse/dot1.C: New test.

From-SVN: r106408