On Tue, Oct 6, 2015 at 4:49 PM, Joerg Sonnenberger via cfe-commits <cfe-commits@lists.llvm.org> wrote: > On Tue, Oct 06, 2015 at 04:20:05PM -0400, Aaron Ballman via cfe-commits wrote: >> On Tue, Oct 6, 2015 at 4:12 PM, Joerg Sonnenberger via cfe-commits >> <cfe-commits@lists.llvm.org> wrote: >> > On Mon, Oct 05, 2015 at 07:36:08PM +0000, Aaron Ballman via cfe-commits >> > wrote: >> >> C-style variadic functions (using an ellipsis) can be dangerous in C++ >> >> due to the inherit lack of type safety with argument passing. Better >> >> alternatives exist, such as function currying (like STL stream objects >> >> use), or function parameter packs. This patch adds a checker to >> >> diagnose definitions of variadic functions in C++ code, but still >> >> allows variadic function declarations, as those can be safely used to >> >> good effect for SFINAE patterns. >> > >> > I would restrict this a bit to exclude function definitions with C >> > linkage. If you have such a ABI requirement, you normally can't replace >> > it with any of the alternatives. >> >> Under what circumstances would you run into this issue with C++ code? >> The only circumstance I can think of is if you have a C API that takes >> a function pointer to a varargs function as an argument. Is that the >> situation you are thinking of, or are there others? > > Consider a stdio implementation written in C++? Wouldn't the > implementation of e.g. vprintf trigger exactly this warning?
It would, but it would also trigger a *lot* of warnings that aren't directed at implementers as well, such as anything about relying on implementation-defined or undefined behavior (like the implementation of offsetof(), as a trivial example). It's a good point to keep in mind though. Thanks! ~Aaron _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
