On 06/09/18 21:29, Juan Cabrera wrote:
> Hello!
>
> Thank you for your answers.
> I'm aware that you can cast anything into an `enum class` but I
> thought that casting a non valid enum-class value into an enum-class
> was itself "wrong" or "unedfined behavior" or something like that :D.
>
> I just checked and it looks like clang does not emit a warning in this case.
>
> I guess I'll have to add a return statement to that function to keep
> the compiler from complaning :D
>
It is usually not a good idea to change code just to stop the compiler
from complaining. Unless it is a false positive warning where you know
the code is good, listen to the compiler.
To me, there are two choices. One is that you believe "f" /might/ be
called with a T that is not A or B. In that case, you should handle it
appropriately - not just have a fake return to keep the compiler quiet.
For example:
int f(T t) {
switch (t) {
case T::A : return 10;
case T::B : return 20;
}
throw std::runtime_error("Calling f with a bad t");
}
Alternatively, if you are sure that "f" will never be called with an
inappropriate t, tell the compiler that:
int f(T t) {
switch (t) {
case T::A : return 10;
case T::B : return 20;
}
__builtin_unreachable();
}
That at least can lead to better code, and perhaps give more checking or
optimisation opportunities.
In between these are things like "assert" and the option of checking
during development and testing, and disabling checks at later stages.
A "just return something" solution usually combines the disadvantages of
all these options.
