> With an assert() modified to give compile-time warnings when possible, you will generally have run-time costs. Hmm. Not true, the __builtin_choose_expr( __builtin_constant_p(exp)) completely vanishes at run time in optimized code. The only downsides are.... * it does something slightly different to the posix standard. Hence probably should have a slightly different name. * it's a gcc extension (but seems to work well with clang) * it doesn't work with C++ On Fri, May 11, 2018 at 6:21 PM, David Brown <david@xxxxxxxxxxxxxxx> wrote: > > > On 10/05/18 00:30, John Carter wrote: > > It catches things that can be inlined but seen as constant at comile time. >> >> I think as gcc's optimizer get's smarter this will be quite a win. >> >> It also basically subsumes static_assert() >> > > This does not replace static_assert. The key point about static_assert is > that it is /always/ static - zero cost at run-time or code size. You know > that is the case when you write it, and other people reading the code know > that. So static_asserts are always free, and can be used liberally. With > an assert() modified to give compile-time warnings when possible, you will > generally have run-time costs. > > > > -- John Carter Phone : (64)(3) 358 6639 Tait Electronics PO Box 1645 Christchurch New Zealand -- This Communication is Confidential. We only send and receive email on the basis of the terms set out at www.taitradio.com/email_disclaimer <http://www.taitradio.com/email_disclaimer>
