Properly select "Release" build for Travis

[karzhenkov]

Ninja doesn't support multiple build configurations. The option --config Release has no effect when cmake --build is called. Essentially, all testing was performed for "Debug" configuration, which is the default. Maybe it doesn't really matter, but it's misleading. The proper way to select build configuration here is through CMAKE_BUILD_TYPE.

[coveralls]

Coverage remained the same at 99.982% when pulling bf75a1b on karzhenkov:fix-travis-release into 6f55193 on nlohmann:develop.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[karzhenkov]

The coverage test requires the use of the "Debug" configuration. From the GCC documentation:

if you want to prove that every single line in your program was executed, you should not compile with optimization at the same time

[nlohmann]

@karzhenkov Can you please update to the latest develop branch? I changed a lot of issues in the CI and moved some checks from Travis to GitHub Actions. Maybe the changes of this PR may need to be applied in cmake/ci.cmake.

[karzhenkov]

I think there is nothing here that we can apply to cmake\ci. cmake.

[nlohmann]

Looks good to me.

[nlohmann]

Thanks!