[PATCH] D13446: [PATCH] Add checker discouraging definition of variadic function definitions in C++

[Joerg Sonnenberger via cfe-commits]

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 at 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?

Joerg