Passing custom (newer) C++ standard in cmake

[NikolausDemmel]

In the cmake configuration the CXX_STANDARD property of the library is set to a fixed value of 11.

opengv/CMakeLists.txt

Line 184 in 306a54e

CXX_STANDARD 11

I'm building opengv as part of my project and would like to set a different (newer) C++ standard from outside. However, currently passing CMAKE_CXX_STANDARD does nothing and is overwritten. As a workaround I modify the CMakeLists.txt, but ideally I would like to pull in the unmodified upstream version.

Is there currently a way to pass a custom C++ standard version from "outside"?

What would be a good way to implement this? Instead of putting a fixed value of 11, we could check if CMAKE_CXX_STANDARD is set. If yes, we use that, if not, we default to 11. Would that be an acceptable change, or does that have possible downsides?

[NikolausDemmel]

Looks like the proper modern cmake way is something like

target_compile_features(opengv PUBLIC cxx_std_11)

which according to a quick test can be overwritten by setting CMAKE_CXX_STANDARD. Unfortunately that is a cmake 3.8+ feature.