Doesn't compile anymore on FreeBSD

[puffetto]

Hi there,
I am cleaning up a project using Crow, it did compile and run on FreeBSD12.2 and Crow pulled from old commit 4a6d5fe, using crow_all.h
Now I am trying to compile FreeBSD 13.1-RELEASE using current Crow from GIT and I get:

In file included from /home/blackye/prcd/programs/prcd-postal.cpp:11:
In file included from /usr/local/include/crow_all.h:105:
/usr/include/c++/v1/unordered_map:776:17: error: no viable overloaded '='
        __ref() = _VSTD::forward<_ValueTp>(__v);
        ~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/v1/__hash_table:1713:47: note: in instantiation of function template specialization 'std::__hash_value_type<std::string, crow::json::wvalue>::operator=<const std::pair<const std::string, crow::json::wvalue> &, void>' requested here
                __cache->__upcast()->__value_ = *__first;
                                              ^
/usr/include/c++/v1/unordered_map:1720:14: note: in instantiation of function template specialization 'std::__hash_table<std::__hash_value_type<std::string, crow::json::wvalue>, std::__unordered_map_hasher<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::hash<std::string>, std::equal_to<std::string>, true>, std::__unordered_map_equal<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::equal_to<std::string>, std::hash<std::string>, true>, std::allocator<std::__hash_value_type<std::string, crow::json::wvalue>>>::__assign_unique<const std::pair<const std::string, crow::json::wvalue> *>' requested here
    __table_.__assign_unique(__il.begin(), __il.end());
             ^
/usr/local/include/crow_all.h:8234:26: note: in instantiation of member function 'std::unordered_map<std::string, crow::json::wvalue>::operator=' requested here
                    (*o) = initializer_list;
                         ^
/usr/include/c++/v1/__utility/pair.h:257:11: note: candidate function not viable: no known conversion from 'const std::pair<const std::string, crow::json::wvalue>' to 'const typename conditional<is_copy_assignable<first_type>::value && is_copy_assignable<second_type>::value, pair<string &, wvalue &>, __nat>::type' (aka 'const std::__nat') for 1st argument
    pair& operator=(typename conditional<
          ^
/usr/include/c++/v1/__utility/pair.h:270:11: note: candidate function not viable: no known conversion from 'const std::pair<const std::string, crow::json::wvalue>' to 'typename conditional<is_move_assignable<first_type>::value && is_move_assignable<second_type>::value, pair<string &, wvalue &>, __nat>::type' (aka 'std::__nat') for 1st argument
    pair& operator=(typename conditional<
          ^
/usr/include/c++/v1/__utility/pair.h:79:62: note: candidate template ignored: disabled by 'enable_if' [with _Tuple = const std::pair<const std::string, crow::json::wvalue> &]
    using _EnableB _LIBCPP_NODEBUG_TYPE = typename enable_if<_Val, bool>::type;
                                                             ^
/usr/include/c++/v1/__utility/pair.h:42:29: note: candidate function (the implicit copy assignment operator) not viable: no known conversion from 'const pair<const std::string, crow::json::wvalue>' to 'const pair<std::string &, crow::json::wvalue &>' for 1st argument
struct _LIBCPP_TEMPLATE_VIS pair
                            ^

Using #include <crow.h> instead of crow_all doesn't change it.

Compiler is as follows:

blackye@rigatino:~/prcd/build-FreeBSD /usr/bin/cc --version
FreeBSD clang version 13.0.0 ([email protected]:llvm/llvm-project.git llvmorg-13.0.0-0-gd7b669b3a303)
Target: x86_64-unknown-freebsd13.1
Thread model: posix
InstalledDir: /usr/bin

Any hint?

[puffetto]

Additional info:
the issue arises even configuring Crow with a plain cmake and trying to compile its own tests:

blackye@rigatino:~ git clone https://github.com/CrowCpp/Crow.git
Cloning into 'Crow'...
remote: Enumerating objects: 54732, done.
remote: Counting objects: 100% (3414/3414), done.
remote: Compressing objects: 100% (380/380), done.
remote: Total 54732 (delta 2970), reused 3324 (delta 2912), pack-reused 51318
Receiving objects: 100% (54732/54732), 38.07 MiB | 20.91 MiB/s, done.
Resolving deltas: 100% (48742/48742), done.
blackye@rigatino:~ cd Crow
blackye@rigatino:~/Crow mkdir build
blackye@rigatino:~/Crow cd build
blackye@rigatino:~/Crow/build cmake ..
-- The CXX compiler identification is Clang 13.0.0
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- No build type selected, default to Release
-- Found asio: /usr/local/include  
-- The C compiler identification is Clang 13.0.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- example_compression example deactivated
-- example_ssl example deactivated
-- Compression tests are omitted. (Configure with CROW_FEATURES containing 'compression' to enable them)
-- SSL tests are omitted. (Configure with CROW_FEATURES containing 'ssl' to enable them)
-- Configuring done
-- Generating done
-- Build files have been written to: /home/blackye/Crow/build
blackye@rigatino:~/Crow/build make
[  2%] Building CXX object examples/CMakeFiles/helloworld.dir/helloworld.cpp.o
In file included from /home/blackye/Crow/examples/helloworld.cpp:1:
In file included from /home/blackye/Crow/include/crow.h:2:
In file included from /home/blackye/Crow/include/crow/query_string.h:7:
/usr/include/c++/v1/unordered_map:776:17: error: no viable overloaded '='
        __ref() = _VSTD::forward<_ValueTp>(__v);
        ~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/v1/__hash_table:1713:47: note: in instantiation of function template specialization 'std::__hash_value_type<std::string, crow::json::wvalue>::operator=<const std::pair<const std::string, crow::json::wvalue> &, void>' requested here
                __cache->__upcast()->__value_ = *__first;
                                              ^
/usr/include/c++/v1/unordered_map:1720:14: note: in instantiation of function template specialization 'std::__hash_table<std::__hash_value_type<std::string, crow::json::wvalue>, std::__unordered_map_hasher<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::hash<std::string>, std::equal_to<std::string>, true>, std::__unordered_map_equal<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::equal_to<std::string>, std::hash<std::string>, true>, std::allocator<std::__hash_value_type<std::string, crow::json::wvalue>>>::__assign_unique<const std::pair<const std::string, crow::json::wvalue> *>' requested here
    __table_.__assign_unique(__il.begin(), __il.end());
             ^
/home/blackye/Crow/include/crow/json.h:1659:26: note: in instantiation of member function 'std::unordered_map<std::string, crow::json::wvalue>::operator=' requested here
                    (*o) = initializer_list;
                         ^
/usr/include/c++/v1/__utility/pair.h:257:11: note: candidate function not viable: no known conversion from 'const std::pair<const std::string, crow::json::wvalue>' to 'const typename conditional<is_copy_assignable<first_type>::value && is_copy_assignable<second_type>::value, pair<string &, wvalue &>, __nat>::type' (aka 'const std::__nat') for 1st argument
    pair& operator=(typename conditional<
          ^
/usr/include/c++/v1/__utility/pair.h:270:11: note: candidate function not viable: no known conversion from 'const std::pair<const std::string, crow::json::wvalue>' to 'typename conditional<is_move_assignable<first_type>::value && is_move_assignable<second_type>::value, pair<string &, wvalue &>, __nat>::type' (aka 'std::__nat') for 1st argument
    pair& operator=(typename conditional<
          ^
/usr/include/c++/v1/__utility/pair.h:79:62: note: candidate template ignored: disabled by 'enable_if' [with _Tuple = const std::pair<const std::string, crow::json::wvalue> &]
    using _EnableB _LIBCPP_NODEBUG_TYPE = typename enable_if<_Val, bool>::type;
                                                             ^
/usr/include/c++/v1/__utility/pair.h:42:29: note: candidate function (the implicit copy assignment operator) not viable: no known conversion from 'const pair<const std::string, crow::json::wvalue>' to 'const pair<std::string &, crow::json::wvalue &>' for 1st argument
struct _LIBCPP_TEMPLATE_VIS pair
                            ^
In file included from /home/blackye/Crow/examples/helloworld.cpp:1:
In file included from /home/blackye/Crow/include/crow.h:2:
In file included from /home/blackye/Crow/include/crow/query_string.h:7:
/usr/include/c++/v1/unordered_map:757:17: error: no viable overloaded '='
        __ref() = __v.__get_value();
        ~~~~~~~ ^ ~~~~~~~~~~~~~~~~~
/usr/include/c++/v1/__hash_table:1753:47: note: in instantiation of member function 'std::__hash_value_type<std::string, crow::json::wvalue>::operator=' requested here
                __cache->__upcast()->__value_ = *__first;
                                              ^
/usr/include/c++/v1/__hash_table:1550:9: note: in instantiation of function template specialization 'std::__hash_table<std::__hash_value_type<std::string, crow::json::wvalue>, std::__unordered_map_hasher<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::hash<std::string>, std::equal_to<std::string>, true>, std::__unordered_map_equal<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::equal_to<std::string>, std::hash<std::string>, true>, std::allocator<std::__hash_value_type<std::string, crow::json::wvalue>>>::__assign_multi<std::__hash_const_iterator<std::__hash_node<std::__hash_value_type<std::string, crow::json::wvalue>, void *> *>>' requested here
        __assign_multi(__u.begin(), __u.end());
        ^
/usr/include/c++/v1/unordered_map:1053:18: note: in instantiation of member function 'std::__hash_table<std::__hash_value_type<std::string, crow::json::wvalue>, std::__unordered_map_hasher<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::hash<std::string>, std::equal_to<std::string>, true>, std::__unordered_map_equal<std::string, std::__hash_value_type<std::string, crow::json::wvalue>, std::equal_to<std::string>, std::hash<std::string>, true>, std::allocator<std::__hash_value_type<std::string, crow::json::wvalue>>>::operator=' requested here
        __table_ = __u.__table_;
                 ^
/home/blackye/Crow/include/crow/json.h:1678:26: note: in instantiation of member function 'std::unordered_map<std::string, crow::json::wvalue>::operator=' requested here
                    (*o) = value;
                         ^
/usr/include/c++/v1/__utility/pair.h:257:11: note: candidate function not viable: no known conversion from 'const std::__hash_value_type<std::string, crow::json::wvalue>::value_type' (aka 'const pair<const std::string, crow::json::wvalue>') to 'const typename conditional<is_copy_assignable<first_type>::value && is_copy_assignable<second_type>::value, pair<string &, wvalue &>, __nat>::type' (aka 'const std::__nat') for 1st argument
    pair& operator=(typename conditional<
          ^
/usr/include/c++/v1/__utility/pair.h:270:11: note: candidate function not viable: no known conversion from 'const std::__hash_value_type<std::string, crow::json::wvalue>::value_type' (aka 'const pair<const std::string, crow::json::wvalue>') to 'typename conditional<is_move_assignable<first_type>::value && is_move_assignable<second_type>::value, pair<string &, wvalue &>, __nat>::type' (aka 'std::__nat') for 1st argument
    pair& operator=(typename conditional<
          ^
/usr/include/c++/v1/__utility/pair.h:79:62: note: candidate template ignored: disabled by 'enable_if' [with _Tuple = const std::pair<const std::string, crow::json::wvalue> &]
    using _EnableB _LIBCPP_NODEBUG_TYPE = typename enable_if<_Val, bool>::type;
                                                             ^
/usr/include/c++/v1/__utility/pair.h:42:29: note: candidate function (the implicit copy assignment operator) not viable: no known conversion from 'const pair<const std::__hash_value_type<std::string, crow::json::wvalue>::key_type, std::__hash_value_type<std::string, crow::json::wvalue>::mapped_type>' to 'const pair<std::string &, crow::json::wvalue &>' for 1st argument
struct _LIBCPP_TEMPLATE_VIS pair
                            ^
2 errors generated.
*** Error code 1

Stop.
make[2]: stopped in /usr/home/blackye/Crow/build
*** Error code 1

Stop.
make[1]: stopped in /usr/home/blackye/Crow/build
*** Error code 1

Stop.
make: stopped in /usr/home/blackye/Crow/build
blackye@rigatino:~/Crow/build 

[puffetto]

Compiles and seems to work with requested pull.
Cheers,
A.