A variadic macro is a feature of some computer programming languages, especially the C preprocessor, whereby a macro may be declared to accept a varying number of arguments.
Variable-argument macros were introduced in 1999 in the ISO/IEC 9899:1999 (C99) revision of the C language standard, and in 2011 in ISO/IEC 14882:2011 (C++11) revision of the C++ language standard.[1] Support for variadic macros with no arguments was added in C++20 and will be added in C23.[2][3]
N3033
was invoked but never defined (see the help page).