a clean macro to make a part of code obsolete

[D_Drmmr]

Why not just comment the code out? If you use the block comment/uncomment command (select a block and Ctrl+K, Ctrl+C / Ctrl+K, Ctrl+U in VC) it's also easier to reactivate the code part by part (no need for adding #ifdef / #endif pairs)

The problem with that approach is that it doesn't work if there is already a block comment in your code or if you want blocks within blocks.

void foo()
{
/*
/*
*/ // comment ends here
*/ // compiler error
}