On Thu, May 9, 2013 at 11:41 AM, Jason Merrill <ja...@redhat.com> wrote: > At the last C++ standards meeting, we agreed to add VLAs to the language. > But they're significantly different from GNU/C99 VLAs: you can't form a > pointer to a VLA, or take its sizeof, or really anything other than directly > use it. We also need to throw an exception if we try to create one with a > negative or too large bound. And we need to support lambda capture and > range-based for loops. > > The one thing I'm nervous about is our handling of an array which turns out > at runtime to be of length 0. GCC has always allowed zero-length arrays, > and they work fine, so I don't want to break existing code, but I also want > to offer a fully-conforming mode. What I ended up deciding to do is throw > on zero with -std=c++1y and not with -std=gnu++1y. But I'm not terribly > comfortable with this answer; anyone have any better ideas?
I am fine with this distinction. I suspect that we don't have too many codes with VLA array with zero length in existing C++ mode. > > The first patch accepts VLAs in C++1y mode and adds new functionality; the > second patch adds diagnostics for invalid uses of C++1y VLAs. > > Tested x86_64-pc-linux-gnu, applying to trunk.
