The C++ standard states that returning reference to a local variable (on the stack) is undefined behaviour, so why do many (if not all) of the current compilers only give a warning for doing so?
struct A{
};
A& foo()
{
A a;
return a; //gcc and VS2008 both give this a warning, but not a compiler error
}
Would it not be better if compilers give a error instead of warning for this code?
Are there any great advantages to allowing this code to compile with just a warning?
Please note that this is not about a const reference which could lengthen the lifetime of the temporary to the lifetime of the reference itself.