* cp-tree.h (EXPR_STMT_ASSIGNS_THIS): New macro.
(STMT_IS_FULL_EXPR_P): Likewise.
(STMT_LINENO_FOR_FN_P): Likewise.
(prep_stmt): New function.
(building_stmt_tree): Tweak for safety.
* pt.c (tsubst_expr): Use prep_stmt throughout.
(add_tree): Move it to semantics.c
* semantics.c (add_tree): Move it here.
(finish_expr_stmt_real): New function.
(finish_expr_stmt): Use it.
(finish_if_stmt_cond): Use FINISH_COND.
(finish_while_stmt_cond): Likewise.
(finish_for_cond): Likewise.
(finish_stmt_tree): Tweak line-number handling.
(prep_stmt): New function.
(expand_stmt): Use it.