c++: ICE with invalid use of 'this' with static memfn [PR98800]

c++: ICE with invalid use of 'this' with static memfn [PR98800]

Here instantiation of the fake 'this' parameter we used when parsing the
trailing return type of func() was failing because there is no actual 'this'
parameter in the instantiation.  For PR97399 I told Patrick to do the 'this'
injection even for statics, but now I think I was wrong; the out-of-class
definition case I was concerned about does not break with this patch.  And
we don't set current_class_ptr in the body of a static member function.

And the OMP code should continue to parse 'this' and complain about it
rather than give a syntax error.

gcc/cp/ChangeLog:

	PR c++/98800
	PR c++/97399
	* parser.c (cp_parser_direct_declarator): Don't
	inject_this_parameter if static_p.
	(cp_parser_omp_var_list_no_open): Parse 'this' even if
	current_class_ptr isn't set for a better diagnostic.

gcc/testsuite/ChangeLog:

	PR c++/98800
	* g++.dg/gomp/this-1.C: Adjust diagnostic.
	* g++.dg/cpp0x/constexpr-this1.C: New test.