EOS compilation produces "fatal error: 'nlohmann/json.hpp' file not found"

[ekkis]

I'll start by admitting this may belong in the EOS support but just in case someone here knows about this I'm posting here

• What is the issue you have?

cannot seem to include the .hpp file in my EOS project

• Please describe the steps to reproduce the issue. Can you provide a small but working code example?

$ brew tap nlohmann/json
$ brew install nlohmann_json
$ brew test nlohmann_json
$ cat "#include <nlohmann/json.hpp>" > t.cpp
$ eosio-cpp -o t.wasm t.cpp --abigen

• What is the expected behavior?

successful compilation

• And what is the actual behavior instead?

t.cpp:1:10: fatal error: 'nlohmann/json.hpp' file not found
#include <nlohmann/json.hpp>
^~~~~~~~~~~~~~~~~~~
1 error generated.

• Which compiler and operating system are you using? Is it a supported compiler?

using the EOS compiler

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

the released version

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

I presume these are run with brew test ... -- they ran successfully (no errors)

[ekkis]

@nlohmann it would be great if we could have support for this library within EOS but it's a rather restrictive environment. I cross posted this issue and got a discouraging reply but perhaps something that would encourage you to look into it, as a challenge, perhaps?

EOSIO/eosio.contracts#167

[nlohmann]

This seems to be a problem with the include directories which is more related to the invocation of the compiler rather than the compiler itself. The brew command outputs (brew info nlohmann_json):

If built with CMake support, you can use find_package to use the library.

Without it, please set your include path accordingly:
CPPFLAGS: -I/usr/local/opt/nlohmann_json/include

I do not know the compiler that you are using, but you should try

eosio-cpp -I/usr/local/opt/nlohmann_json/include -o t.wasm t.cpp --abigen

[nlohmann]

@ekkis Does this solve your issue?

[ekkis]

what I did was just to download, the .hpp, put it in the local directory and include it like #include "json.hpp"; -- however it was a futile effort because EOS is a very restrictive environment and doing Json parsing in it would make the smart contracts substantially larger so I dumped the whole concept

thanks for the reply and attempt to help all the same