* c-common.h (c_tree_index): Add CTI_VOID_ZERO.
	(void_zero_node): New macro.
	(struct stmt_tree_s): New type.
	(stmt_tree): New typedef.
	(struct language_function): New type.
	(last_tree): New macro.
	(last_expr_type): Likewise.
	(walk_tree_fn): New typedef.
	(current_stmt_tree): New function.
	(begin_stmt_tree): Likewise.
	(add_stmt): Likewise.
	(finish_stmt_tree): Likewise.
	(statement_code_p): Likewise.
	(lang_statement_code_p): New variable.
	(walk_stmt_tree): New function.
	(STMT_IS_FULL_EXPR_P): New macro.
	* c-common.c (lang_statement_code_p): New variable.
	(c_common_nodes_and_builtins): Initialize void_zero_node.
	(statement_code_p): New function.
	(walk_stmt_tree): Likewise.
	* c-decl.c (language_function): Rename to ...
	(c_language_function): ... this.  Include language_function.
	(push_c_function_context): Adjust accordingly.
	(pop_c_function_context): Likewise.
	(mark_c_function_context): Likewise.
	(current_stmt_tree): Define.
	* c-semantics.c (begin_stmt_tree): New function.
	(add_stmt): Likewise.
	(prune_unused_decls): Likewise.
	(finish_stmt_tree): Likewise.

	Move statement-tree facilities from C++ to C front-end.
	* cp-tree.h (cp_tree_index): Remove CPTI_VOID_ZERO.
	(void_zero_node): Remove.
	(stmt_tree): Likewise.
	(scope_chain): Adjust.
	(language_function): Rename to cp_language_function.
	(cp_function_chain): Adjust.
	(current_stmt_tree): Remove.
	(last_tree): Likewise.
	(last_expr_type): Likewise.
	(struct lang_decl): Adjust.
	(STMT_IS_FULL_EXPR_P): Remove.
	(add_tree): Remove.
	(begin_stmt_tree): Likewise.
	(finish_stmt_tree): Likewise.
	(walk_tree_fn): Likewise.
	(walk_stmt_tree): Likewise.
	* class.c (finish_struct): Replace use of add_tree with add_stmt.
	* decl.c (mark_stmt_tree): Adjust type.
	(init_decl_processing): Don't build void_zero_node.
	(initialize_local_var): Adjust usage of current_stmt_tree.
	(finish_enum): Use add_stmt, not add_tree.
	(save_function_data): Adjust use of language_function.
	(finish_constructor_body): Use add_stmt, not add_tree.
	(finish_destructor_body): Likewise.
	(push_cp_function_context): Adjust use of language_function.
	(pop_cp_function_context): Likewise.
	(mark_lang_function): Likewise.
	(mark_cp_function_context): Likewise.
	* init.c (build_aggr_init): Adjust use of current_stmt_tree.
	(build_vec_init): Likewise.
	* semantics.c (SET_LAST_STMT): Remove.
	(RECHAIN_STMTS): Don't use it.
	(stmts_are_full_exprs_p): Adjust use of current_stmt_tree.
	(current_stmt_tree): Define.
	(add_tree): Remove.
	(finish_goto_stmt): Use add_stmt, not add_tree.
	(finish_expr_stmt): Likewise.
	(begin_if_stmt): Likewise.
	(finish_then_clause): Likewise.
	(begin_while_stmt): Likewise.
	(begin_do_stmt): Likewise.
	(finish_return_stmt): Likewise.
	(begin_for_stmt): Likewise.
	(finish_break_stmt): Likewise.
	(finish_continue_stmt): Likewise.
	(begin_switch_stmt): Likewise.
	(finish_case_label): Likewise.
	(begin_try_block): Likewise.
	(begin_function_try_block): Likewise.
	(begin_handler): Likewise.
	(begin_catch_block): Likewise.
	(begin_compound_stmt): Likewise.
	(begin_asm_stmt): Likewise.
	(finish_asm_stmt): Likewise.
	(finish_label_stmt): Likewise.
	(add_decl_stmt): Likewise.
	(finish_subobject): Likewise.
	(finish_decl_cleanup): Likewise.
	(finish_named_return_value): Likewise.
	(setup_vtbl_ptr): Likewise.
	(add_scope_stmt): Likewise.
	(finish_stmt_expr): Likewise.
	(prune_unused_decls): Remove.
	(begin_stmt_tree): Likewise.
	(finish_stmt_tree): Likewise.
	(prep_stmt): Adjust use of current_stmt_tree.
	(lang_expand_stmt): Likewise.
	* tree.c (statement_code_p): Remove.
	(cp_statement_code_p): New function.
	(walk_stmt_tree): Remove.
	(init_tree): Set lang_statement_code_p.

From-SVN: r36221