// Regular cast, which has been verified to be legal by the programmer:
{
    long x;
    auto y = cast(int) x;
}

// However this will still compile if 'x' is changed to be a pointer:
{
    long* x;
    auto y = cast(int) x;
}

// castFrom provides a more reliable alternative to casting:
{
    long x;
    auto y = castFrom!long.to!int(x);
}

// Changing the type of 'x' will now issue a compiler error,
// allowing bad casts to be caught before it's too late:
{
    long* x;
    static assert(
        !__traits(compiles, castFrom!long.to!int(x))
    );

    // if cast is still needed, must be changed to:
    auto y = castFrom!(long*).to!int(x);
}