c++: Use of 'this' in parameter declaration [PR90748]

c++: Use of 'this' in parameter declaration [PR90748]

We were incorrectly accepting the use of 'this' at parse time and then
crashing when we tried to instantiate it.  It is invalid because 'this' is
not in scope until after the function-cv-quals.  So let's hoist setting
current_class_ptr up from cp_parser_late_return_type_opt into
cp_parser_direct_declarator where it can work for noexcept as well.

gcc/cp/ChangeLog
2020-05-11  Jason Merrill  <jason@redhat.com>

	PR c++/90748
	* parser.c (inject_parm_decls): Set current_class_ptr here.
	(cp_parser_direct_declarator): And here.
	(cp_parser_late_return_type_opt): Not here.
	(cp_parser_noexcept_specification_opt): Nor here.
	(cp_parser_exception_specification_opt)
	(cp_parser_late_noexcept_specifier): Remove unneeded parameters.