On Mon, Sep 17, 2018 at 1:53 PM, Paolo Carlini <paolo.carl...@oracle.com> wrote: > Hi again, > > On 9/3/18 10:59 PM, Paolo Carlini wrote: >> >> in this error-recovery ICE, upon the error make_constrained_auto assigns >> error_mark_node to PLACEHOLDER_TYPE_CONSTRAINTS (type) which then causes a >> crash later when hash_placeholder_constraint is called on it. I think we >> should cope with this somehow, I believe that consistency with the way we >> use error_mark_node in this part of the front-end prevents us from avoiding >> to assign the error_mark_node in the first place and, for the reasons >> explained in my previous patch, we want to unconditionally call >> make_constrained_auto. This said, catching in practice the error_mark_node >> would normally mean renouncing to the pattern 'if (tree c = ...)' which we >> lately appear to like a lot and seems indeed neat. Thus I'm wondering if we >> want instead to add a macro like ERROR_AS_NULL, which of course would be >> also useful in many other places - essentially in all the circumstances >> where we want to check for a kosher node, thus neither null nor >> error_mark_node. What do you think? What about the name, in case? Tested >> x86_64-linux. > > > Today I reviewed again this issue, for which I sent a tentative patch a > couple of weeks ago. All in all, I still believe that is the right place to > catch the error_mark_node and avoid ICE-ing later, the quick rationale being > that PLACEHOLDER_TYPE_CONSTRAINTS can be error_mark_node for other reasons > too. As regards the ERROR_AS_NULL idea, I'm still not sure, on one hand it > would allow for more compact and neat code in some cases, on the other hand > could be seen as some sort of obfuscation - well, some people out there > consider an obfuscation the very 'if (c =...)' pattern ;) Anyway, I'm > attaching the normal versions of the fix, which, per a recent message from > Jason, probably is almost obvious...
Hmm, I do kind of like the ERROR_AS_NULL idea. I might call it NON_ERROR, though. OK with that change. Jason
