[Bug sanitizer/106739] New: runtime error coredump case on c++17/20

["zhkefa at live dot cn" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106739

            Bug ID: 106739
           Summary: runtime error coredump case on c++17/20
           Product: gcc
           Version: 10.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhkefa at live dot cn
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at gcc dot gnu.org
  Target Milestone: ---

code file test.cc:
=============================
class A {
public:
    A(int i): i(i){}
    int get() {return i;}
private:
    int i{0};
};

void func() {
    typedef int (A::*f)();
    f fs[] = {&A::get};
    A *a = new A{1};
    for (int i = 0; i < 1; ++i) {
        (a->*fs[i])();
    }
    delete a;
}

int main() {
    func();
    return 0;
}

===============
envirment: gcc10.4

g++ -fsanitize=address -fsanitize=undefined -std=c++17 test.cc

./a.out
runtime error: index 4198816 out of bounds for type func[1]
runtime error: load of address 0x7ffd97570f08 whith insufficient space for an
object of type 'long int'

if compile with -std=c++14 or -std=c++11, everything ok.