双端队列迭代器不可递减

Question

I try to run this code with MSVC 2017:

#include <vector>
#include <deque>

class StripPtR {
public:
    int i;
    StripPtR (int i) : i(i) {}
};

typedef std::deque<StripPtR> StripType;
typedef std::vector<StripType> StripsType;

int main(int, char**) {
    StripType a{ {1}, {2}, {3} };

    a.insert(a.end(), a.rbegin() + 1, a.rend());

    return 0;
}

And I get this error:

Deque iterator not decrementable

Error

The error occurs at runtime. During compile time there is no error or warning.

The same code works fine with GCC.

What is wrong?

Answer 1

std::deque::insert says:

All iterators, including the past-the-end iterator, are invalidated.

The MSVC version probably loops through, incrementing/decrementing first (or a.rbegin() + 1 in your code) which means that the insert works but afterwards these iterators are invalidated and cause your runtime error. This version results in that you can't pass iterators to the same container you insert into.