Compiler optimizations expose hidden UB risk in C/C++ type punning

A developer traced a hard-to-find bug to type punning via pointer casts, which behaves correctly at -O0 but breaks under -O2 optimization. The root cause is that pointer casts violate strict aliasing rules and constitute undefined behavior in C, even though they compile and run correctly on most platforms, and C++ treats type distinctions even more strictly than C.