fix the abi tests for diagnostics positions feature

[hnampally]

This PR changes fix the issue #4571, when 'JSON_Diagnostic_Positions' cmake option is enabled, we need to cover JSON_DIAGNOSTIC_POSITIONS preprocessor directive as well.

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Pull request checklist

Read the Contribution Guidelines for detailed information.

• Changes are described in the pull request, or an existing issue is referenced.
• The test suite compiles and runs without error.
• Code coverage is 100%. Test cases can be added by editing the test suite.
• The source code is amalgamated; that is, after making changes to the sources in the include/nlohmann directory, run make amalgamate to create the single-header files single_include/nlohmann/json.hpp and single_include/nlohmann/json_fwd.hpp. The whole process is described here.

[coveralls]

coverage: 99.639%. remained the same
when pulling cec0474 on harytary:issue4571-abi-tests-fix
into 6be4e85 on nlohmann:develop.

[nlohmann]

Looks good to me.

[nlohmann]

Thanks! We really need to add a CI step for this...

[hnampally]

Yes, I will raise a PR for a CI step as well.

[nlohmann]

Yes, I will raise a PR for a CI step as well.

That would be the place to add the change: https://github.com/nlohmann/json/blob/develop/cmake/ci.cmake#L894_L955

Target ci_cmake_flags is executed by the CI in the Ubuntu workflow, but right now, we only call CMake with the respective flags, but do not build and run the tests.

[hnampally]

Yes, I will raise a PR for a CI step as well.

That would be the place to add the change: https://github.com/nlohmann/json/blob/develop/cmake/ci.cmake#L894_L955

Target ci_cmake_flags is executed by the CI in the Ubuntu workflow, but right now, we only call CMake with the respective flags, but do not build and run the tests.

Okay sounds good, thanks for the link.

[nlohmann]

Thanks! We really need to add a CI step for this...

Added with #4579.