sandboxed-api/cmake/protobuf/Download.cmake
Christian Blichmann 3c51348aaf Enable CMake projects to consume Sandboxed API via add_subdirectory()
This change moves away from a classical superbuild which downloads and builds
at build time. Instead, we now follow a "Fetch Content" workflow (available as
FetchContent in CMake 3.11+) and download dependencies at config time.

Rationale: Superbuild projects have the disadvantage that projects cannot
directly access their individual declared targets. This is not a problem with
regular libraries, as those are usually/supposed to be installed. With
Sandboxed API, this is not desirable, as it has dependencies like Abseil and
glog, which are almost always consumed by including their source tree using
add_subdirectory().

Fixes #10 and makes external embedding easier.

PiperOrigin-RevId: 260129870
Change-Id: I70f295f29a6e4fc8c330512c94b01ef10c017166
2019-07-26 05:51:08 -07:00

41 lines
1.5 KiB
CMake

# Copyright 2019 Google LLC. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Downloads and unpacks Protobuf at configure time
set(workdir "${CMAKE_BINARY_DIR}/protobuf-download")
configure_file("${CMAKE_CURRENT_LIST_DIR}/CMakeLists.txt.in"
"${workdir}/CMakeLists.txt")
execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
RESULT_VARIABLE error
WORKING_DIRECTORY "${workdir}")
if(error)
message(FATAL_ERROR "CMake step for ${PROJECT_NAME} failed: ${error}")
endif()
execute_process(COMMAND ${CMAKE_COMMAND} --build .
RESULT_VARIABLE error
WORKING_DIRECTORY "${workdir}")
if(error)
message(FATAL_ERROR "Build step for ${PROJECT_NAME} failed: ${error}")
endif()
set(protobuf_BUILD_TESTS OFF CACHE BOOL "")
set(protobuf_BUILD_SHARED_LIBS OFF CACHE BOOL "")
set(protobuf_WITH_ZLIB OFF CACHE BOOL "")
add_subdirectory("${CMAKE_BINARY_DIR}/protobuf-src/cmake"
"${CMAKE_BINARY_DIR}/protobuf-build" EXCLUDE_FROM_ALL)