remove abi uncertainty and potential abi conflict (pytorch#94306)

Currently there is a potential conflict for `GLIBCXX_USE_CXX11_ABI` configuration if users don't explicitly set this variable.
In `caffe2/CMakeLists.txt`, if the variable is not set, an `abi checker` will be used to retrieve the ABI configuration from compiler.
https://github.com/pytorch/pytorch/blob/master/caffe2/CMakeLists.txt#L1165-L1183
However, in 'torch/csrc/Module.cpp`, if the variable is not set, it will be set to `0`. The conflict happens when the default ABI of the compiler is `1`.
https://github.com/pytorch/pytorch/blob/master/torch/csrc/Module.cpp#L1612

This PR eliminate this uncertainty and potential conflict.
The ABI will be checked and set in `CMakeLists.txt`, and pass the value to `caffe2/CMakeLists.txt`. Meanwhile, in case the `caffe2/CMakeLists.txt` is directly invoked from a `cmake` command, The original GLIBC check logic is kept in this file.
If users doesn't explicitly assign a value to `GLIBCXX_USE_CXX11_ABI`, the `abi checker` will be executed and set the value accordingly. If the `abi checker` failed to compile or execute, the value will be set to `0`. If users explicitly assigned a value, then the provided value will be used.

Moreover, if `GLIBCXX_USE_CXX11_ABI` is set to `0`, the '-DGLIBCXX_USE_CXX11_ABI=0' flag won't be appended to `CMAKE_CXX_FLAGS`. Thus, whether to use ABI=0 or ABI=1 fully depends on compiler's default configuration. It could cause an issue that even users explicitly set `GLIBCXX_USE_CXX11_ABI` to `0`, the compiler still builds the binaries with ABI=1.
https://github.com/pytorch/pytorch/blob/master/CMakeLists.txt#L44-L51
Pull Request resolved: pytorch#94306
Approved by: https://github.com/malfet

Author: jingxu10

CMakeLists.txt

@@ -40,14 +40,19 @@ endif()
 set(CMAKE_CXX_STANDARD 17 CACHE STRING "The C++ standard whose features are requested to build this target.")
 set(CMAKE_C_STANDARD   11 CACHE STRING "The C standard whose features are requested to build this target.")
 
-if(DEFINED GLIBCXX_USE_CXX11_ABI)
+# ---[ Utils
+include(cmake/public/utils.cmake)
+
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  include(cmake/CheckAbi.cmake)
+  string(APPEND CMAKE_CXX_FLAGS " -D_GLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI}")
   if(${GLIBCXX_USE_CXX11_ABI} EQUAL 1)
     set(CXX_STANDARD_REQUIRED ON)
-    string(APPEND CMAKE_CXX_FLAGS " -D_GLIBCXX_USE_CXX11_ABI=1")
   else()
     # Please note this is required in order to ensure compatibility between gcc 9 and gcc 7
     # This could be removed when all Linux PyTorch binary builds are compiled by the same toolchain again
-    string(APPEND CMAKE_CXX_FLAGS " -fabi-version=11")
+    include(CheckCXXCompilerFlag)
+    append_cxx_flag_if_supported("-fabi-version=11" CMAKE_CXX_FLAGS)
   endif()
 endif()
 
@@ -631,9 +636,6 @@ if(INTERN_BUILD_MOBILE)
   set(INTERN_DISABLE_MOBILE_INTERP ON)
 endif()
 
-# ---[ Utils
-include(cmake/public/utils.cmake)
-
 # ---[ Version numbers for generated libraries
 file(READ version.txt TORCH_DEFAULT_VERSION)
 # Strip trailing newline

caffe2/CMakeLists.txt

@@ -1157,31 +1157,8 @@ if(BUILD_TEST)
   endif()
 endif()
 
-# XXX This ABI check cannot be run with arm-linux-androideabi-g++
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
-  if(DEFINED GLIBCXX_USE_CXX11_ABI)
-    message(STATUS "_GLIBCXX_USE_CXX11_ABI is already defined as a cmake variable")
-  else()
-    message(STATUS "${CMAKE_CXX_COMPILER} ${TORCH_SRC_DIR}/abi-check.cpp -o ${CMAKE_BINARY_DIR}/abi-check")
-    execute_process(
-      COMMAND
-      "${CMAKE_CXX_COMPILER}"
-      "${TORCH_SRC_DIR}/abi-check.cpp"
-      "-o"
-      "${CMAKE_BINARY_DIR}/abi-check"
-      RESULT_VARIABLE ABI_CHECK_COMPILE_RESULT)
-    if(ABI_CHECK_COMPILE_RESULT)
-      message(FATAL_ERROR "Could not compile ABI Check: ${ABI_CHECK_COMPILE_RESULT}")
-    endif()
-    execute_process(
-      COMMAND "${CMAKE_BINARY_DIR}/abi-check"
-      RESULT_VARIABLE ABI_CHECK_RESULT
-      OUTPUT_VARIABLE GLIBCXX_USE_CXX11_ABI)
-    if(ABI_CHECK_RESULT)
-      message(WARNING "Could not run ABI Check: ${ABI_CHECK_RESULT}")
-    endif()
-  endif()
-  message(STATUS "Determined _GLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI}")
+  include(../cmake/CheckAbi.cmake)
 endif()
 
 # CMake config for external projects.

cmake/CheckAbi.cmake

@@ -0,0 +1,27 @@
+if(DEFINED GLIBCXX_USE_CXX11_ABI)
+  message(STATUS "_GLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI} is already defined as a cmake variable")
+  return()
+endif()
+
+# XXX This ABI check cannot be run with arm-linux-androideabi-g++
+message(STATUS "${CMAKE_CXX_COMPILER} ${PROJECT_SOURCE_DIR}/torch/abi-check.cpp -o ${CMAKE_BINARY_DIR}/abi-check")
+execute_process(
+  COMMAND
+  "${CMAKE_CXX_COMPILER}"
+  "${PROJECT_SOURCE_DIR}/torch/abi-check.cpp"
+  "-o"
+  "${CMAKE_BINARY_DIR}/abi-check"
+  RESULT_VARIABLE ABI_CHECK_COMPILE_RESULT)
+if(ABI_CHECK_COMPILE_RESULT)
+  message(FATAL_ERROR "Could not compile ABI Check: ${ABI_CHECK_COMPILE_RESULT}")
+  set(GLIBCXX_USE_CXX11_ABI 0)
+endif()
+execute_process(
+  COMMAND "${CMAKE_BINARY_DIR}/abi-check"
+  RESULT_VARIABLE ABI_CHECK_RESULT
+  OUTPUT_VARIABLE GLIBCXX_USE_CXX11_ABI)
+if(ABI_CHECK_RESULT)
+  message(WARNING "Could not run ABI Check: ${ABI_CHECK_RESULT}")
+  set(GLIBCXX_USE_CXX11_ABI 0)
+endif()
+message(STATUS "Determined _GLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI}")