What's considered critical or difficult to discover is a bit subjective, but: It's easy to forget that alignment is important on some architectures (other than

What's considered critical or difficult to discover is a bit subjective, but: It's easy to forget that alignment is important on some architectures (other than for performance reasons), so be careful when using placement new: https://www.securecoding.cert.org/confluence/display/cplusplus/MEM54-CPP.+Provide+placement+new+with+properly+aligned+pointers+to+sufficient+storage+capacity https://www.securecoding.cert.org/confluence/display/cpluspl... This may seem obvious, but even the C++ committee got this one wrong when they created auto_ptr (which has since been removed from the standard): https://www.securecoding.cert.org/confluence/display/cplusplus/OOP58-CPP.+Copy+operations+must+not+mutate+the+source+object https://www.securecoding.cert.org/confluence/display/cpluspl... This one is totally obvious but has a stunning number of ways you can fail to adhere to it, some of which look reasonable at first blush: https://www.securecoding.cert.org/confluence/display/cplusplus/EXP54-CPP.+Do+not+access+an+object+outside+of+its+lifetime https://www.securecoding.cert.org/confluence/display/cpluspl...