LSan can be used in 3 ways. Standalone (-fsanitize=leak) AddressSanitizer (-fsanitize=address) HWAddressSanitizer (-fsanitize=hwaddress) The most common way to use LSan is clang -fsanitize=address (or gcc -fsanitize=address). For LSan-supported targets (#define CAN_SANITIZE_LEAKS 1), the AddressSanitizer (ASan) runtime enables LSan by default.