__FILE__, __LINE__, and __FUNCTION__ usage in C++
c++, c-preprocessor, debugging, logging
Solution
`__FUNCTION__` is non standard, `__func__` exists in C99 / C++11. The others (`__LINE__` and `__FILE__`) are just fine.
It will always report the right file and line (and function if you choose to use `__FUNCTION__`/`__func__`). Optimization is a non-factor since it is a compile time macro expansion; it will never affect performance in any way.
Problem
Presuming that your C++ compiler supports them, is there any particular reason not to use `__FILE__`, `__LINE__` and `__FUNCTION__` for logging and debugging purposes? I'm primarily concerned with giving the user misleading data—for example, reporting the incorrect line number or function as a result of optimization—or taking a performance hit as a result. Basically, can I trust `__FILE__`, `__LINE__` and `__FUNCTION__` to always do the right thing?