target_compile_features no known features for CXX compiler for clang 9.0
Trying to build Ceres, I'm running into an issue in which CMake 3.11.0-rc3 doesn't seem to recognize the clang that comes with the latest Xcode (Version 9.2 (9C40b)). Googling turns up similar, but old results, that seem to suggest one needs to update CMake. But -rc4 is the only more recent version, and its release notes don't say anything about this.
CMake Error at cmake/AddCeresCXX11RequirementsToTarget.cmake:70 (target_compile_features):
target_compile_features no known features for CXX compiler
to work, since the target_compile_features command expects
behavior as of CMake 3.1 or above. Typically the command
would only be used after `cmake_minimum_required(VERSION 3.1)`
which would automatically set CMP0025 to NEW.
Ceres is trying to support older CMake versions and so would
need to set the policy manually.