Someone who gets error on build with cmake

[jangmin-deepx]

who uses C++ under 20 (17 or 13) might get error on build with cmake.

As ortools(stable or maybe main) uses C++20 (see here) should install C++20 or use ex-version of ortools.
in my case, ortools with v9.0 worked

message(STATUS "Fetching or-tools...")
include(FetchContent)
FetchContent_Declare(
  or-tools
  GIT_REPOSITORY https://github.com/google/or-tools.git
  GIT_TAG        v9.0     <== change here main -> v9.0
  )
FetchContent_MakeAvailable(or-tools)
message(STATUS "Done fetching or-tools")

I hope this issue helps someone with same issue.

[jangmin-deepx]

• use set(BUILD_DEPS ON) to build all the deps(absl, protobuf, ... etc) if you dont have one or it will raise error.