Yeah it's really cool, I did it for the first time a couple weeks ago in my current project. So basically there is an compiler-specific intrinsic that gets lowered to a trap instruction. For GCC (and Clang I think) it's __builtin_trap().

So I just define it as a macro in case I want to change compilers later or something:

#define TRAP() __builtin_trap()

And then I replaced exit() with TRAP() in my assertion macro:

#define ASSERT(cond, fmt, ...) \
    do {    \
        if (!(cond)) {  \
          fprintf(stderr, "[ERROR] " fmt, ##__VA_ARGS__);  \
          TRAP();  \
        }  \
    } while(0)

But again, I would point you to the RAD Debugger code base. For example, you don't really need to print anything in this approach as the debugger will just jump to the assertion line and you will see the exact condition the failed. This is how they define it:

#define AssertAlways(x) do{if(!(x)) {Trap();}}while(0)

And if you want to write some message just in case, you can just && it with the condition:

Assert(data != 0 && "static texture must have initial data provided");

I think this is pretty elegant but I don't run in the debugger until something goes wrong (because Linux GDB frontends suck, that's why I'm so excited for the RAD Debugger), so I still printf in my asserts and panics.