Can different optimization levels lead to functionally different code?

Question

I am curious about the liberties that a compiler has when optimizing. Let\'s limit this question to GCC and C/C++ (any version, any flavour of standard):

Is it possi

Answer 1

Since copy constructor calls can be optimized away, even if they have side effects, having copy constructors with side-effects will cause unoptimized and optimized code to behave differently.