C++ FE: handle misspelled identifiers and typenames

C++ FE: handle misspelled identifiers and typenames

gcc/cp/ChangeLog:
	PR c/70339
	PR c/71858
	* name-lookup.c: Include gcc-rich-location.h, spellcheck-tree.h,
	and parser.h.
	(suggest_alternatives_for): If no candidates are found, try
	lookup_name_fuzzy and report if if finds a suggestion.
	(consider_binding_level): New function.
	(lookup_name_fuzzy) New function.
	* parser.c: Include gcc-rich-location.h.
	(cp_lexer_next_token_is_decl_specifier_keyword): Move most of
	logic into...
	(cp_keyword_starts_decl_specifier_p): ...this new function.
	(cp_parser_diagnose_invalid_type_name): When issuing
	"does not name a type" errors, attempt to make a suggestion using
	lookup_name_fuzzy.
	* parser.h (cp_keyword_starts_decl_specifier_p): New prototype.
	* search.c (lookup_field_fuzzy_info::fuzzy_lookup_field): Reject
	types that are not CLASS_TYPE_P, rather than rejecting individual
	tree codes.

gcc/testsuite/ChangeLog:
	PR c/70339
	PR c/71858
	* g++.dg/spellcheck-identifiers.C: New test case, based on
	gcc.dg/spellcheck-identifiers.c.
	* g++.dg/spellcheck-identifiers-2.C: New test case, based on
	gcc.dg/spellcheck-identifiers-2.c.
	* g++.dg/spellcheck-typenames.C: New test case, based on
	gcc.dg/spellcheck-typenames.c

From-SVN: r238538