Build Error C2039 with MSVC when using /std:c++latest (C++20) - std::is_literal_type removed

[dongkeren]

Using version 1.7.0, boost/hana/traits.hpp line 73 is causing the error:

constexpr auto is_literal_type = detail::hana_traitstd::is_literal_type{};

My workaround is simply bypass it:

#if __cplusplus > 201704L
constexpr auto is_literal_type = detail::hana_traitstd::is_literal_type{};
#endif

Reference:
https://stackoverflow.com/questions/40351816/deprecated-stdis-literal-type-in-c17

[ldionne]

The problem is that MSVC doesn't set the value of __cplusplus correctly unless you pass /Zc:__cplusplus: https://godbolt.org/z/c6YKTr8dh