The cmake_import example does not build

[coderDec]

• What is the issue you have?
  I am trying to build the cmake_import example json-develop/test/cmake_import/project.
  However it fails to build.
  Following error:

`
cmake .
-- The CXX compiler identification is GNU 7.4.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at CMakeLists.txt:5 (find_package):
By not providing "Findnlohmann_json.cmake" in CMAKE_MODULE_PATH this
project has asked CMake to find a package configuration file provided by
"nlohmann_json", but CMake did not find one.

Could not find a package configuration file provided by "nlohmann_json"
with any of the following names:

nlohmann_jsonConfig.cmake
nlohmann_json-config.cmake

Add the installation prefix of "nlohmann_json" to CMAKE_PREFIX_PATH or set
"nlohmann_json_DIR" to a directory containing one of the above files. If
"nlohmann_json" provides a separate development package or SDK, be sure it
has been installed.

-- Configuring incomplete, errors occurred!
`

• Please describe the steps to reproduce the issue. Can you provide a small but working code example?
  I also put the nlohmann_jsonConfig.cmake file generated while building the project here.

• What is the expected behavior?
  It should build the project

• And what is the actual behavior instead?
  Unable to build using cmake.

• Which compiler and operating system are you using? Is it a supported compiler?
  lsb_release -a
  No LSB modules are available.
  Distributor ID: Ubuntu
  Description: Ubuntu 18.04.3 LTS
  Release: 18.04
  Codename: bionic

• Did you use a released version of the library or the version from the develop branch?
  develop branch

• If you experience a compilation error: can you compile and run the unit tests?
  yes.

[t-b]

Can you post a MWE? We do have tests for the cmake import at https://github.com/nlohmann/json/tree/develop/test already.

[coderDec]

#include </opt/nlohmann_json/json.hpp>
#include<string.h>
// for convenience
using json = nlohmann::json;

int
main(int argc, char *argv[])
{
// create an empty structure (null)
json j;

// add a number that is stored as double (note the implicit conversion of j to an object)
j["pi"] = 3.141;

// add a Boolean that is stored as bool
j["happy"] = true;

// add a string that is stored as std::string
j["name"] = "Niels";

// add another null object by passing nullptr
j["nothing"] = nullptr;

// add an object inside the object
j["answer"]["everything"] = 42;

// add an array that is stored as std::vector (using an initializer list)
j["list"] = { 1, 0, 2 };

// add another object (using an initializer list of pairs)
j["object"] = { {"currency", "USD"}, {"value", 42.99} };

return 0;
}

I have added the json.hpp file in single_include at /opt/nlohmann_json/json.hpp

Tried to compile it with the following command. It fails.
gcc -std=c++11 json_ade.cpp -o json_ade.o

[t-b]

@coderDec You have to pass the include path to gcc.

#include <nlohmann/json.hpp>
#include<string.h>
// for convenience
using json = nlohmann::json;

int
main(int argc, char *argv[])
{
// create an empty structure (null)
json j;

return 0;
}

with g++ -I single_include test.cpp from the base directory of this repository works here.

[nlohmann]

@coderDec Did #1976 (comment) solve your issue?

[coderDec]

Yes it did.