erichkeane wrote: > > > This was discussed in this RFC: > > > https://discourse.llvm.org/t/rfc-diagnosing-use-of-vlas-in-c/73109 and > > > our decision to move forward with that is independent of what GCC does. > > > > > > I saw that discussion, but I do miss where it has been agreed to diverge > > from GCC on this. Maybe more generic question will clear my > > misunderstanding: what is a stance of Clang on`-std=gnu++*`? Can it be > > different to what GCC does? > > Yes, we already differ in many, many ways from GCC in gnu modes, especially > when it comes to diagnostics. We often aim for compatibility, but it's not a > hard requirement that we follow GCC's lead. Other examples include (but > certainly are not limited to): https://godbolt.org/z/sj3oEqj8Y > > > > Without more justification for walking this back, I do not agree with > > > moving forward with the revert. > > > > > > We have library code that has to use VLA in source code in certain scenario > > and rely on compiler to optimize it away. The library is built with `-Wall` > > and after it started to use newer Clang, the error appear. The main concern > > is simple: GCC doesn't do that (yet). Understandably, if GCC agrees to > > diagnose it, that change will need to be reverted. > > Yeah, this sort of problem crops up when we diverge in diagnostic behavior, > but isn't a reason to revert a useful diagnostic. Due to the nature of the > syntax for declaring a VLA, many instances of VLA use in C++ (and even in C) > are purely accidental and C++ often has better alternatives. Because your use > of VLAs is intentional, I'd recommend adding `-Wno-vla` to your build script.
Note that if this is troublesome, we support `#pragma clang diagnostic` that you can wrap around hte individual declarations: https://godbolt.org/z/8eb3bcfTW https://github.com/llvm/llvm-project/pull/89943 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
