How to enable compiler sanitizers in GCC and Clang for zero-cost runtime bug discovery:

g++ -O1 -g -fsanitize=address,undefined,leak -fno-omit-frame-pointer main.cpp -o main

What Sanitizers Catch Instantly:

• Out-of-bounds heap / stack / global array access
• Use-After-Free and Double-Free errors
• Signed integer overflow (UB in C/C++)
• Null pointer dereferences and misaligned pointer casts
• Memory leaks upon process exit with precise file and line numbers!

AddressSanitizer replaced 90% of our Valgrind usage. It runs at only ~2x slowdown compared to Valgrind's 20x slowdown, making it feasible to run during full test suites.

Running UBSan on legacy codebases always exposes unexpected signed overflows in integer math routines.