On Fri, Apr 13, 2018 at 5:05 AM, Paolo Carlini <paolo.carl...@oracle.com> wrote: > Hi, > > in this error-recovery regression, after a sensible error message issued by > cxx_constant_init, store_init_value stores an error_mark_node as > DECL_INITIAL of the VAR_DECL for 'j'. This error_mark_node reappears much > later, to cause a crash during gimplification. As far as I know, the choice > of storing error_mark_nodes too is the outcome of a rather delicate > error-recovery strategy and I don't think we want to revisit it at this > time, thus the remaining option is catching later the error_mark_node, at a > "good" time. I note, in passing, that the do loop in gimplify_expr which > uses the crashing STRIP_USELESS_TYPE_CONVERSION seems a bit lacking from the > error-recovery point of view, because at each iteration it *does* cover for > error_operand_p (save_expr) but only immediately after the call, when it's > too late. > > All the above said, I believe that at least for the 8.1.0 needs we may want > to catch the error_mark_node in cp_build_modify_expr, when we are handling > the assignment 'a.n = j;': convert_for_assignment produces a NOP_EXPR from > the VAR_DECL for 'j' which then cp_convert_and_check regenerates (deep in > convert_to_integer_1 via maybe_fold_build1_loc) in the final bare-bone form, > with the error_mark_node as the first operand. Passes testing on > x86_64-linux.
We should avoid wrapping an error_mark_node in a NOP_EXPR in the first place. Jason