C++: fix fix-it hints for misspellings within explicit namespaces

C++: fix fix-it hints for misspellings within explicit namespaces

gcc/cp/ChangeLog:
	PR c++/77829
	PR c++/78656
	* cp-tree.h (suggest_alternatives_for): Add bool param.
	(suggest_alternative_in_explicit_scope): New decl.
	* error.c (qualified_name_lookup_error): When SCOPE is a namespace
	that isn't the global one, call new function
	suggest_alternative_in_explicit_scope, only calling
	suggest_alternatives_for if it fails, and disabling near match
	searches fort that case.  When SCOPE is the global namespace,
	pass true for new param to suggest_alternatives_for to allow for
	fuzzy name lookups.
	* lex.c (unqualified_name_lookup_error): Pass true for new param
	to suggest_alternatives_for.
	* name-lookup.c (consider_binding_level): Add forward decl.
	(suggest_alternatives_for): Add "suggest_misspellings" param,
	using it to conditionalize the fuzzy name-lookup code.
	(suggest_alternative_in_explicit_scope): New function.
	* parser.c (cp_parser_primary_expression): When calling
	finish_id_expression, pass location of id_expression rather
	than that of id_expr_token.
	(cp_parser_id_expression): Convert local "unqualified_id" from
	tree to cp_expr to avoid implicitly dropping location information.

gcc/testsuite/ChangeLog:
	PR c++/77829
	PR c++/78656
	* g++.dg/spellcheck-pr77829.C: New test case.
	* g++.dg/spellcheck-pr78656.C: New test case.

From-SVN: r244715