Again, strlen is a stupid example as it is well documented. All of llvm and clang are not. > On Sep 20, 2016, at 1:59 PM, Zachary Turner <ztur...@google.com> wrote: > > > > On Tue, Sep 20, 2016 at 1:55 PM Greg Clayton <gclay...@apple.com> wrote: > > > On Sep 20, 2016, at 1:45 PM, Zachary Turner <ztur...@google.com> wrote: > > > > I do agree that asserts are sometimes used improperly. But who's to say > > that the bug was the assert, and not the surrounding code? For example, > > consider this code: > > > > assert(p); > > int x = *p; > > Should be written as: > > assert(p); > if (!p) > do_something_correct(); > else > int x = *p; > > > > > Should this assert also not be here in library code? I mean it's obvious > > that the program is about to crash if p is invalid. Asserts should mean > > "you're about to invoke undefined behavior", and a crash is *better* than > > undefined behavior. It surfaces the problem so that you can't let it slip > > under the radar, and it also alerts you to the point that the UB is > > invoked, rather than later. > > > > What about this assert? > > > > assert(ptr); > > int x = strlen(ptr); > > > > Surely that assert is ok right? Do we need to check whether ptr is valid > > EVERY SINGLE TIME we invoke strlen, or any other function for that matter? > > The code would be a disastrous mess. > > Again, check before you call if this is in a shared library! What is so hard > about that? It is called software that doesn't crash. > > assert(ptr) > int x = ptr ? strlen(ptr) : 0; > > I find it hard to believe that you are arguing that you cannot EVER know > ANYTHING about the state of your program. :-/ > > This is like arguing that you should run a full heap integrity check every > time you perform a memory write, just to be sure you aren't about to crash. > > If you make a std::vector<>, do we need to verify that its internal pointer > is not null before we write to it? Probably not, right? Why not? Because > it has a specification of how it works, and it is documented that you can > construct one, you can use it. > > It's ok to document how functions work, and it is ok to assume that functions > work the way they claim to work.
_______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
