The "cmake/CMakeLists.txt -> CMakeLists.txt" redirection deactivates some policies silently.

[jtattermusch]

The "cmake/CMakeLists.txt" is now deprecated, but there are some hidden problems with how it's forwarding to /CMakeLists.txt (in the repo root).

I found that some cmake policies get silently deactivated if one uses cmake/CMakeLists.txt

E.g. here:

protobuf/CMakeLists.txt

Line 10 in 244b245

if(POLICY CMP0091)

Since CMP0091 needs to be set before languages are initialized, but

protobuf/cmake/CMakeLists.txt

Line 5 in 244b245

project(protobuf C CXX)

is reached first, the policy won't be active (which is quite counterintuitive)
and settings made here

protobuf/CMakeLists.txt

Line 233 in 244b245

if (protobuf_MSVC_STATIC_RUNTIME)

will be overridden by e.g. /MD still being present in CMAKE_CXX_FLAGS_*

(at least this is my interpretation of what happens, but I've observed /MD flag being present when it should not).

[acozzette]

I think we should probably just delete that file at this point. @jtattermusch Would that be ok from your perspective or would that break gRPC?