CMakeLists.txt

cmake_minimum_required (VERSION 3.25..3.31)

set (CMAKE_CXX_STANDARD 17)
set (CMAKE_CXX_STANDARD_REQUIRED ON)

project (Example LANGUAGES CXX)

include (FetchContent)
FetchContent_Declare (
  protobuf
  GITHUB_REPOSITORY https://github.com/protocolbuffers/protobuf.git
  GITHUB_TAG main
  SOURCE_SUBDIR cmake
  FIND_PACKAGE_ARGS NAME protobuf
)
FetchContent_MakeAvailable (
  protobuf
)

include (FindProtobuf)
find_package (Protobuf REQUIRED)   # <- not possible, it hasn't been built

add_target (MyBufs)
target_include_directories (MyBufs PUBLIC ${CMAKE_BINARY_DIR})
target_include_directories (MyBufs PUBLIC ${Protobuf_INCLUDE_DIRS})
target_link_libraries      (MyBufs PUBLIC ${Protobuf_LIBRARIES})

# Collect a list of the .proto files in this directory
file (GLOB _protos *.proto)

# Tell cmake that we need to use those with protoc to generate the .cpp/.h files
PROTOBUF_GENERATE_CPP (
  _sources _headers
  ${_protos}
)

# Add those as sources to the library (it won't try to compile the headers,
# but it ought to notice if they change for rebuild purposes)
target_sources (
  MyBuffs
  ${_sources}
  ${_headers}
)