[Bug c++/86385] New: calling wrong constructors?

[zhonghao at pku dot org.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86385

            Bug ID: 86385
           Summary: calling wrong constructors?
           Product: gcc
           Version: 8.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhonghao at pku dot org.cn
  Target Milestone: ---

The code is as follow:

struct A {
 int* a;
 A(int a) : a(new int(a)) {}
 ~A() { delete a; }

 A(const A&) = delete;
 A(A&& other) { a = other.a; other.a = 0; };

 operator bool() { return true; }
 int operator*() { return *a; }
};

static A makeA(int x) { return A(x); }

int main() {
 A c = makeA(42) ?: makeA(-1);
 return *c;
}

g++ error:

error: lvalue required as unary '&' operand
  A c = makeA(42) ?: makeA(-1);

It seems that g++ considers 42 and -1 as const A& or A&& other, instead of
integer values. Or else, it does not produce such a message. I tried clang++.
It accepts the code. For me, the results of clang++ are more reasonable.