Programs can not be compiled compile with header nlohmann/json.hpp

[Silver Ghost]

Ubuntu release 18.04.1
Package version 2.1.1-1.1

Bug is reported already reported and resolved in upstream.

Compiling error from upstream issue about Ubuntu[0]:
In file included from test_json.cpp:6:0:
/usr/include/nlohmann/json.hpp: In function ‘bool nlohmann::operator<(nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer>::const_reference, nlohmann::basic_json<ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer>::const_reference)’:
/usr/include/nlohmann/json.hpp:6057:62: error: wrong number of template arguments (1, should be 2)
                     return *lhs.m_value.array < *rhs.m_value.array;
                                                              ^~~~~
In file included from /usr/include/nlohmann/json.hpp:33:0,
                 from test_json.cpp:6:
/usr/include/c++/7/array:94:12: note: provided for ‘template<class _Tp, long unsigned int _Nm> struct std::array’
     struct array
            ^~~~~

Upstream issue discussing this bug - [1]

Proposed solution[2]:
> Changing the line in json.hpp to read
> return (*lhs.m_value.array) < *rhs.m_value.array;
> seems to fix the error using that simple test case.

Bug was fixed in [3]. Versions >=3.0.0 has this fix.

[0] https://github.com/nlohmann/json/issues/1110
[1] https://github.com/nlohmann/json/issues/590
[2] https://github.com/nlohmann/json/issues/590#issuecomment-305988306
[3] https://github.com/nlohmann/json/commit/1a9d76679a3f41a038a89742fba29d81ee24ce82