PR c++/92907 - noexcept does not consider "const" in member functions.

PR c++/92907 - noexcept does not consider "const" in member functions.

Here the problem is that if the noexcept specifier is used in the context
of a const member function, const is not considered for the member variables,
leading to a bogus error.  g's const makes its 'this' const, so the first
overload of f should be selected.

In cp_parser_noexcept_specification_opt we inject 'this', but always
unqualified:
25737           if (current_class_type)
25738             inject_this_parameter (current_class_type, TYPE_UNQUALIFIED);
so we need to pass the function's qualifiers down here.  In
cp_parser_direct_declarator it's easy: use the just parsed cv_quals, in
cp_parser_late_noexcept_specifier look at the 'this' parameter to figure it
out.

2020-01-22  Marek Polacek  <polacek@redhat.com>

	PR c++/92907 - noexcept does not consider "const" in member functions.
	* parser.c (cp_parser_lambda_declarator_opt): Pass the proper
	qualifiers to cp_parser_exception_specification_opt.
	(cp_parser_direct_declarator): Pass the function qualifiers to
	cp_parser_exception_specification_opt.
	(cp_parser_class_specifier_1): Pass the function declaration to
	cp_parser_late_noexcept_specifier.
	(cp_parser_late_noexcept_specifier): Add a tree parameter.  Use it to
	pass the qualifiers of the function to
	cp_parser_noexcept_specification_opt.
	(cp_parser_noexcept_specification_opt): New cp_cv_quals parameter.
	Use it in inject_this_parameter.
	(cp_parser_exception_specification_opt): New cp_cv_quals parameter.
	Use it.
	(cp_parser_transaction): Pass TYPE_UNQUALIFIED to
	cp_parser_noexcept_specification_opt.
	(cp_parser_transaction_expression): Likewise.

	* g++.dg/cpp0x/noexcept56.C: New test.