Is there a compiler option for ignoring undefined references? I'm compiling C++ code under Linux.
No. This is impossible. The linker physically cannot produce an output executable with an undefined reference. It's not a choice that the linker makes.
It's kind of like saying, "Sort this list, but I won't tell you what the list is" or "Solve my problem but I only dumped the code".
You are not compiling, you are linking. The undefined reference error occurs when the program you are linking calls a function which is not defined inside the program parts you are linking together. Ignoring that error would mean the program calls a function that does not exist - what should happen then?
So the short answer is: theres no such option, and it would not make sense.
The compiler already does ignore undefined references, quite by design.