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question: how to correctly create print helpers for '<<' explicitly removed in C++20? #409
Description
Hello!
while project description states that this framework is for C++17 max, could anyone possibly help me with C++20 compatibility issue?
my problem is that in C++20 operator << for printing wide strings (std::wstring, `const wchar_t*, etc) was explicitly removed. In C++17 I could define helper template like
template<> std::ostream& operator<<(std::ostream& o, const std::wstring& what) { o << convert_to_char(what); return o; }
and it worked perfectly. In C++20 this no longer works, as this operator is explicitly deleted, so this template is not even considered. I found that I can partially solve the issue for std::wstring by defining this specialization
namespace boost {
namespace test_tools {
namespace tt_detail {
namespace impl {
template<> std::ostream& boost_test_print_type_impl::operator()(std::ostream& o, const std::wstring& what) const
{
o << convert_to_char(what); return o;
}
} // impl
} // tt_detail
} // test_tools
} // boost
but this works only for std::wstring, not for any wide string literals in a test like
BOOST_TEST(someWideString == L"expectations");
as I found no way to match R const& r against wchar_t[12] so I can't create a specialization in similar manner.
what need to be done, so BOOST_TEST could understand wide string literals in C++20?
if you need compiler specifics: this is Xcode 15 on macOS
Activity
mbel1 commentedon Jan 30, 2024
It turned out that I was incorrect in my analysis of the problem: it turned out that old workaround with
std::ostream& operator<<(std::ostream& o, const std::wstring& what)works just fine. But with C++20 this workaround no longer works for wide-string literals likeL"expectation": when C++ tries to applytd::ostream& operator<<(std::ostream& o, const wchar_t* what)it finds that it is deleted, so conversion tostd::wstringis not considered. So obvious fix is to use wstring's, likebut is there a way to make
BOOST_TESTto work withconst wchar_t*?zhihaoy commentedon Apr 18, 2024
BOOST_TESTdoes work withconst wchar_t*(not necessarily printing the string); it just doesn't work withconst wchar_t[N].BOOST_TESThas special handling for pointers to arrays of characters because pointers might be null. Arrays, on the other hand, rely on the presence of<<.My current workaround is