Container print overwrites user defined print

[bebuch]

Minimal example:

#include <boost/ut.hpp>

// a user defined container like type (in practice, for example, a matrix)
struct A: std::vector<int>{ using std::vector<int>::vector; };

// with user defined print
std::ostream& operator<<(std::ostream& os, A const& a){
    using namespace boost::ut;
    os << "A{";
    auto first = true;
    for (auto const& v: a) {
      os << (first ? "" : ", ") << v;
      first = false;
    }
    os << "}";
    return os;
}

int main(){
    std::cout << A{0}; // used defined print
    boost::ut::expect(boost::ut::eq(A{1}, A{2})); // unexpected ut container print
}

Expected Behavior

On the second output line, I would expect the user defined output to be called to get this:

A{0}
  main.cpp:20:FAILED [A{1} == A{2}]
===============================================================================
tests:   0 | 0 failed
asserts: 1 | 0 passed | 1 failed

Actual Behavior

Currently the user defined output overload is ignored. Instead the UT container output is used:

A{0}
  main.cpp:20:FAILED [{1} == {2}]
===============================================================================
tests:   0 | 0 failed
asserts: 1 | 0 passed | 1 failed

Steps to Reproduce the Problem

Compile and execute the minimal example.

Specifications

• Version: µt 1.1.8
• Platform: GCC 11 on 64 Bit x86 Linux