Hi,
What would be useful is a format effector that processes a format string and a va_list (recursive call inside vsnprintf).But adding non-standard effectors is not really a good idea.I once added such a thing (I think I used %@). It was easy, but I never used it very much and never rolled it forward (it was 1.4T I added it to). Never even got around to adding it to -Wformat.
Note that that doesn't work with our current gcc on machines where (__builtin_,)va_list is implemented as an array with one element. That means (AFAIK) all machines where some parameters are passed in registers, like e.g. amd64 or powerpc. See my PR#45138. Ciao, Wolfgang -- Wolfgang%Solfrank.net@localhost Wolfgang Solfrank