C++ language wrongly propagated through dependency chain

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7

Hi,

It seems I have rooted down the issue to cmake version.

with CMake 3.5 (a version that I must kept compliant with), language is set with target_compile_options(L PUBLIC $<$<COMPILE_LANGUAGE:CXX>:-std=c++14>)
and
target_compile_options(A PUBLIC $<$<COMPILE_LANGUAGE:CXX>:-std=c++17>)

my issue with CMake 3.19 was that I forgot to rebuild also L with 3.19 and L package was propagating L target_compile_options.

So the issues narrows down to how properly propagate language on CMake version that does not support target_compile_features(… cxx_std_17|cxx_std_14|…)?

Thanks