_LIBC definition in a C ++ program

Question

Some of the GNU library code may have advanced debugging if the _LIBC flag is set. When using -D_LIBC during compilation, it displays the error message "/usr/include/gnu/stubs.h:7haps: #error Applications cannot determine the _LIBC macro"

So how do you define this variable?

Answer 1

You define it when compiling LibC. This is Open Source, after all.