building with cmake

[ozcanay]

Description

Cmake .. && make -j does not work properly on CentOS-7

Reproduction steps

I am having trouble compiling the project. Here is what I am doing:

git clone https://github.com/nlohmann/json.git
cd json
mkdir build
cd build
cmake ..

So far, so good.

However, when I execute:

make -j

Nothing happens, no response at all.

Expected vs. actual results

I was expecting makefile to produce any message.

Minimal code example

No response

Error messages

No response

Compiler and operating system

gcc 10.1.0, CentOS7

Library version

3.11.2 (develop branch)

Validation

• [ ] The bug also occurs if the latest version from the develop branch is used.
• [ ] I can successfully compile and run the unit tests.

[nlohmann]

Which CMake version are you using? Can you share the complete output of running CMake?

[ozcanay]

[nlohmann]

This is as expected. Your CMake version is so old that JSON_BuildTests_INIT is unconditionally set to OFF, see https://github.com/nlohmann/json/blob/develop/CMakeLists.txt#L35.

Without setting JSON_BuildTests to ON, the tests will not be built.

Fix: Call

cmake .. -DJSON_BuildTests=ON

or upgrade CMake.

[ozcanay]

I would rather see a warning about this issue, though.

[nlohmann]

When the library is included as third-party, no tests should be compiled unless explicitly specified with -DJSON_BuildTests=ON. This is also documented in the README.

In which situation would you expect a warning?