> You won't even get a warning unless -Wextra or -Weverything is turned on. That's because -Wconversion isn't part of -Wextra for some reason. It is part of -W

> You won't even get a warning unless -Wextra or -Weverything is turned on. That's because -Wconversion isn't part of -Wextra for some reason. It is part of -Weverything though, and with that clang does warn: warning: implicit conversion changes signedness: 'int' to 'unsigned long' [-Wsign-conversion] if (sizeof(int) < -1) abort(); ~ ^~