> it should be flagged or not compiled. It will be, if you use clang-tidy (or clang's static analyzer): $ clang-tidy main.cpp -- -std=c++14 1 warning

> it should be flagged or not compiled. It will be, if you use clang-tidy (or clang's static analyzer): $ clang-tidy main.cpp -- -std=c++14 1 warning generated. main.cpp:10:5: warning: Forming reference to null pointer [clang-analyzer-core.NonNullParamChecker] f_unused_parameter(*i); ^ main.cpp:19:7: note: Passing null pointer value via 1st parameter 'i' f(nullptr); ^ main.cpp:19:5: note: Calling 'f' f(nullptr); ^ main.cpp:10:5: note: Forming reference to null pointer f_unused_parameter(*i); ^