* cp-tree.h (enum cp_tree_index): Add CPTI_SOURCE_LOCATION_IMPL.
	(source_location_impl): Define.
	(enum cp_built_in_function): Add CP_BUILT_IN_SOURCE_LOCATION.
	(fold_builtin_source_location): Declare.
	* cp-gimplify.c: Include output.h, file-prefix-map.h and cgraph.h.
	(cp_gimplify_expr, cp_fold): Handle CP_BUILT_IN_SOURCE_LOCATION.
	Formatting fix.
	(get_source_location_impl_type): New function.
	(struct source_location_table_entry,
	struct source_location_table_entry_hash): New types.
	(source_location_table, source_location_id): New variables.
	(fold_builtin_source_location): New function.
	* constexpr.c (cxx_eval_builtin_function_call): Handle
	CP_BUILT_IN_SOURCE_LOCATION.
	* tree.c (builtin_valid_in_constant_expr_p): Likewise.  Formatting
	fix.
	* decl.c (cxx_init_decl_processing): Register
	__builtin_source_location.
	* name-lookup.c (get_std_name_hint): Add source_location entry.

	* g++.dg/cpp2a/srcloc1.C: New test.
	* g++.dg/cpp2a/srcloc2.C: New test.
	* g++.dg/cpp2a/srcloc3.C: New test.
	* g++.dg/cpp2a/srcloc4.C: New test.
	* g++.dg/cpp2a/srcloc5.C: New test.
	* g++.dg/cpp2a/srcloc6.C: New test.
	* g++.dg/cpp2a/srcloc7.C: New test.
	* g++.dg/cpp2a/srcloc8.C: New test.
	* g++.dg/cpp2a/srcloc9.C: New test.
	* g++.dg/cpp2a/srcloc10.C: New test.
	* g++.dg/cpp2a/srcloc11.C: New test.
	* g++.dg/cpp2a/srcloc12.C: New test.
	* g++.dg/cpp2a/srcloc13.C: New test.
	* g++.dg/cpp2a/srcloc14.C: New test.

From-SVN: r278949