That may be, but I want to have all this information in my editor too so my editor can warn me about it. Take something like a developer just defining a macro like __USE_GNU to get rid of a warning about an undefined function; you just have no idea what box of Pandora you just opened up with all this preprocessor magic going on behind the scenes. Who knows? They might even be re-defining MAX_PATH or something. With code making assumptions on the value of this macro you could open up new bugs. I want all this information right there for the developer in his editor.

Also there's just no guarantees on how the software is built; in a lot of cases that's even outside a developer's reach.

But, yeah, since it's next to impossible to actually get to that state then, yes, sadly the only real option left is to analyze your finite set of builds.