Defining _LIBC in C++ Program

Question

Some of the GNU library code can be have enhanced debugging if the flag _LIBC is set. While using -D_LIBC when compiling gives the error message "/usr/include/gnu/stubs.h:7:3: #error Applications may not define the macro _LIBC"

So how do you define this variable?

Answer 1

You'd define it when compiling LibC. It's Open Source, after all.