Warnings with Clang 10

[nlohmann]

With Clang 10.0.0, the following warnings appear.

../single_include/nlohmann/json.hpp:14558:53: warning: implicit conversion changes signedness: 'const int' to 'unsigned long' [-Wsign-conversion]
        return buf + (2 + static_cast<size_t>(-n) + k);
                                                  ~ ^
../single_include/nlohmann/json.hpp:14895:39: warning: implicit conversion loses integer precision: 'decltype(__x.base() - __y.base())' (aka 'long') to 'int'
      [-Wshorten-64-to-32]
                        int index = i - val.m_value.binary->cbegin();
                            ~~~~~   ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../single_include/nlohmann/json.hpp:17727:15: note: in instantiation of member function 'nlohmann::detail::serializer<nlohmann::basic_json<std::map, std::vector,
      std::__1::basic_string<char>, bool, long long, unsigned long long, double, std::allocator, adl_serializer, std::__1::vector<unsigned char, std::__1::allocator<unsigned
      char> > > >::dump' requested here
            s.dump(*this, true, ensure_ascii, static_cast<unsigned int>(indent), serialize_binary);
              ^
../single_include/nlohmann/json.hpp:24020:20: note: in instantiation of member function 'nlohmann::basic_json<std::map, std::vector, std::__1::basic_string<char>, bool, long
      long, unsigned long long, double, std::allocator, adl_serializer, std::__1::vector<unsigned char, std::__1::allocator<unsigned char> > >::dump' requested here
        return h(j.dump());
                   ^

These lines were last changed in 0a82168 (#1967) and 012c966 (#1662).

[EliYk]

Hi,

On Ubuntu 16.04, with the following code in check.cpp:

#include <experimental/string_view>

namespace std {using std::experimental::string_view;}

#include "json.hpp"


int main (){
}

Attempting to compile with:

clang++-10 -std=c++2a -stdlib=libc++ check.cpp

I get :

In file included from check.cpp:5:
In file included from ./json.hpp:68:
In file included from /usr/include/c++/v1/unordered_map:369:
/usr/include/c++/v1/__hash_table:1132:43: error: exception specification in declaration does not match previous declaration
__hash_table<_Tp, _Hash, _Equal, _Alloc>::__hash_table()
                                          ^
/usr/include/c++/v1/__hash_table:839:5: note: previous declaration is here
    __hash_table()
    ^
/usr/include/c++/v1/__hash_table:1200:43: error: exception specification in declaration does not match previous declaration
__hash_table<_Tp, _Hash, _Equal, _Alloc>::__hash_table(__hash_table&& __u)
                                          ^
/usr/include/c++/v1/__hash_table:853:5: note: previous declaration is here
    __hash_table(__hash_table&& __u)
    ^
2 errors generated.

Not sure this is ticket-worthy, so I mentioned it here.

Thanks.
Eli

[nlohmann]

On Ubuntu 16.04, with the following code in check.cpp:

Which library version are you using?

[EliYk]

I apt removed existing libc++ libraries, reinstalled via -

sudo apt install libc++-10-dev libc++abi-10-dev (as per https://apt.llvm.org/)

Now it compiles, thanks!