------- Comment #5 from redi at gcc dot gnu dot org 2010-07-07 09:11 ------- (In reply to comment #3) > > The answer is to > > ensure the first, non-inline virtual function is defined. That's it. > > In my humble opinion, no it's not the answer, at least not in my, and I guess > in many people's cases. I did not want to define it, but wanted to have a > purely virtual function, without definition.
Well if you follow my rule you'd look at your class to see which is the first non-inline virtual and you'd realise frob() isn't pure, and be able to change that if that's what you want. > Again, the wording is just a quick scratch, but your "answer which is it" is > not necessarily the right solution either. It's better to be able to fix the general case by following a simple rule than to make the compiler enumerate all the possible ways a user might have got it wrong. The ways to write invalid code are almost infinite. There's often only one way to get it right. > > Suggestions about "unintentionally becoming non-pure" would cause more > > confusion than they would help. > > Well, it can be rephrased. Maybe something like "Did you intend to make it a > pure virtual function? Add `= 0' then. Otherwise, ensure to define the > function." would be the better solution. I disagree. It's far more common for this error to be caused by a missing definition, or by having no non-inline virtuals, than a function which is meant to be pure but has been declared wrong. You've made a particular mistake and you're asking for the compiler to be modified to tell you exactly what you need to change. There are a few different ways to get this error, I don't think yours is the most common, so I don't think your suggestion is the right one. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44841
