Do not use any global compiler settings in CMake build

This change also tries to make the build more idempotent wrt to embedding projects.

PiperOrigin-RevId: 257177255
Change-Id: I291cd02840496db901f829e902623887f6e0eb10

CMakeLists.txt

@@ -22,6 +22,9 @@ if(USE_SUPERBUILD)
 endif()
 project(sandboxed_api C CXX ASM)
 
+# SAPI-wide setting for the language level
+set(SAPI_CXX_STANDARD 11)
+
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 list(APPEND CMAKE_PREFIX_PATH
   "${PROJECT_BINARY_DIR}/Dependencies/Build/gflags"
@@ -29,7 +32,6 @@ list(APPEND CMAKE_PREFIX_PATH
   "${PROJECT_BINARY_DIR}/Dependencies/Build/protobuf"
 )
 
-include(SapiCompilerOptions)
 include(SapiUtil)
 include(GoogleTest)
 
@@ -39,9 +41,14 @@ find_path(absl_src_dir
   HINTS ${ABSL_ROOT_DIR}
   PATHS ${PROJECT_BINARY_DIR}/Dependencies/Source/absl
 )
+set(_sapi_saved_CMAKE_CXX_STANDARD ${CMAKE_CXX_STANDARD})
+set(CMAKE_CXX_STANDARD ${SAPI_CXX_STANDARD})
 add_subdirectory(${absl_src_dir}
                  ${PROJECT_BINARY_DIR}/Dependencies/Build/absl
                  EXCLUDE_FROM_ALL)
+if(_sapi_saved_CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD "${_sapi_saved_CMAKE_CXX_STANDARD}")
+endif()
 
 # Build Googletest directly, as recommended upstream
 find_path(googletest_src_dir
@@ -49,12 +56,13 @@ find_path(googletest_src_dir
   HINTS ${GOOGLETEST_ROOT_DIR}
   PATHS ${PROJECT_BINARY_DIR}/Dependencies/Source/googletest
 )
-set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+set(gtest_force_shared_crt ON CACHE BOOL "")
 add_subdirectory(${googletest_src_dir}
                  ${PROJECT_BINARY_DIR}/Dependencies/Build/googletest
                  EXCLUDE_FROM_ALL)
 
-# Always use static libraries
+# Prefer to use static libraries
+set(_sapi_saved_CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
 if(WIN32)
   set(CMAKE_FIND_LIBRARY_SUFFIXES .lib .a ${CMAKE_FIND_LIBRARY_SUFFIXES})
 else()
@@ -67,6 +75,8 @@ find_package(Protobuf REQUIRED)
 find_package(Libcap REQUIRED)
 find_package(ZLIB REQUIRED)
 
+set(CMAKE_FIND_LIBRARY_SUFFIXES ${_sapi_saved_CMAKE_FIND_LIBRARY_SUFFIXES})
+
 # Make Bazel-like includes work
 configure_file(cmake/libcap_capability.h.in
                libcap/include/sys/capability.h
@@ -84,6 +94,13 @@ add_library(sapi_base STATIC
   ${PROJECT_BINARY_DIR}/sapi_base_force_cxx_linkage.cc
 )
 add_library(sapi::base ALIAS sapi_base)
+set_target_properties(sapi_base PROPERTIES
+  CXX_STANDARD              ${SAPI_CXX_STANDARD}
+  CXX_STANDARD_REQUIRED     TRUE
+  CXX_EXTENSIONS            FALSE
+  SKIP_BUILD_RPATH          TRUE
+  POSITION_INDEPENDENT_CODE TRUE
+)
 target_include_directories(sapi_base INTERFACE
   ${PROJECT_BINARY_DIR}
   ${PROJECT_SOURCE_DIR}
@@ -91,6 +108,11 @@ target_include_directories(sapi_base INTERFACE
   # Need to reach into Abseil internal headers from a few targets.
   ${PROJECT_BINARY_DIR}/Dependencies/Source/absl
 )
+if(UNIX)
+  target_compile_options(sapi_base INTERFACE
+    -Wno-deprecated
+  )
+endif()
 
 add_library(sapi_test_main INTERFACE)
 add_library(sapi::test_main ALIAS sapi_test_main)

cmake/SapiCompilerOptions.cmake

@@ -1,34 +0,0 @@
-# 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.
-
-set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
-set(CMAKE_CXX_STANDARD 11)
-set(CMAKE_CXX_EXTENSIONS OFF)
-
-set(CMAKE_SKIP_BUILD_RPATH TRUE)
-set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
-
-# Compiler-specific global options
-if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")  # GCC
-elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-else()
-  message(FATAL_ERROR "Unsupported compiler")
-endif()
-
-# OS-specific global options
-if(UNIX)
-  add_compile_options(-Wno-deprecated)
-else()
-  message(FATAL_ERROR "Unsupported OS")
-endif()