Simplify cmake code (pytorch#91546)

We use various newer CMake features to simplify build system:
1.Caffe2::threads is replaced by threads::threads.
2.Some unused MSVC flags are removed.

Pull Request resolved: pytorch#91546
Approved by: https://github.com/malfet, https://github.com/Skylion007

Author: cyyever

CMakeLists.txt

@@ -477,14 +477,6 @@ if(MSVC)
     # Turn off warnings on Windows.  In an ideal world we'd be warning
     # clean on Windows too, but this is too much work for our
     # non-Windows developers.
-    #
-    # NB: Technically, this is not necessary if CMP0092 was applied
-    # properly, but only cmake >= 3.15 has this policy, so we nail
-    # it one more time just be safe.
-    #
-    # NB2: This is NOT enough to prevent warnings from nvcc on MSVC.  At the
-    # moment only CMP0092 is enough to prevent those warnings too.
-    string(REPLACE "/W3" "" ${flag_var} "${${flag_var}}")
 
     # Turn off warnings (Windows build is currently is extremely warning
     # unclean and the warnings aren't telling us anything useful.)
@@ -1120,7 +1112,6 @@ if(BUILD_SHARED_LIBS)
       ${PROJECT_SOURCE_DIR}/cmake/public/mkl.cmake
       ${PROJECT_SOURCE_DIR}/cmake/public/mkldnn.cmake
       ${PROJECT_SOURCE_DIR}/cmake/public/protobuf.cmake
-      ${PROJECT_SOURCE_DIR}/cmake/public/threads.cmake
       ${PROJECT_SOURCE_DIR}/cmake/public/utils.cmake
       ${PROJECT_SOURCE_DIR}/cmake/public/LoadHIP.cmake
       DESTINATION share/cmake/Caffe2/public

cmake/Caffe2Config.cmake.in

@@ -13,9 +13,6 @@ set(CAFFE2_VERSION "@CAFFE2_VERSION@")
 # Utils functions.
 include("${CMAKE_CURRENT_LIST_DIR}/public/utils.cmake")
 
-# Include threads lib.
-include("${CMAKE_CURRENT_LIST_DIR}/public/threads.cmake")
-
 # Depending on whether Caffe2 uses gflags during compile time or
 # not, invoke gflags.
 if(@USE_GFLAGS@)

cmake/Dependencies.cmake

@@ -124,9 +124,10 @@ if(MSVC)
 endif(MSVC)
 
 # ---[ Threads
-include(${CMAKE_CURRENT_LIST_DIR}/public/threads.cmake)
-if(TARGET caffe2::Threads)
-  list(APPEND Caffe2_PUBLIC_DEPENDENCY_LIBS caffe2::Threads)
+find_package(Threads REQUIRED)
+if(TARGET Threads::Threads)
+  list(APPEND Caffe2_DEPENDENCY_LIBS Threads::Threads)
+  add_library(caffe2::Threads ALIAS Threads::Threads)
 else()
   message(FATAL_ERROR
       "Cannot find threading library. Caffe2 requires Threads to compile.")
@@ -1080,17 +1081,17 @@ if(BUILD_PYTHON)
 
   # These should fill in the rest of the variables, like versions, but resepct
   # the variables we set above
-  set(Python_ADDITIONAL_VERSIONS ${PYTHON_VERSION} 3.8 3.7)
+  set(Python_ADDITIONAL_VERSIONS ${PYTHON_VERSION} 3.8)
   find_package(PythonInterp 3.0)
   find_package(PythonLibs 3.0)
 
   if(${PYTHONLIBS_VERSION_STRING} VERSION_LESS 3)
     message(FATAL_ERROR
       "Found Python libraries version ${PYTHONLIBS_VERSION_STRING}. Python 2 has reached end-of-life and is no longer supported by PyTorch.")
   endif()
-  if(${PYTHONLIBS_VERSION_STRING} VERSION_LESS 3.7)
+  if(${PYTHONLIBS_VERSION_STRING} VERSION_LESS 3.8)
     message(FATAL_ERROR
-      "Found Python libraries version ${PYTHONLIBS_VERSION_STRING}. Python 3.6 is no longer supported by PyTorch.")
+      "Found Python libraries version ${PYTHONLIBS_VERSION_STRING}. Python < 3.8 is no longer supported by PyTorch.")
   endif()
 
   # When building pytorch, we pass this in directly from setup.py, and
@@ -1145,6 +1146,9 @@ message(STATUS "pybind11 include dirs: " "${pybind11_INCLUDE_DIRS}")
 add_library(pybind::pybind11 INTERFACE IMPORTED)
 target_include_directories(pybind::pybind11 SYSTEM INTERFACE ${pybind11_INCLUDE_DIRS})
 target_link_libraries(pybind::pybind11 INTERFACE python::python)
+if(APPLE)
+  target_link_options(pybind::pybind11 INTERFACE -undefined dynamic_lookup)
+endif()
 
 # ---[ MPI
 if(USE_MPI)

cmake/GoogleTestPatch.cmake

@@ -20,6 +20,5 @@ else(REVERT)
   file(READ ${FILENAME} content)
   file(WRITE ${BACKUP} "${content}")
   string(REGEX REPLACE "[-/]Z[iI]" "/Z7" content "${content}")
-  string(REGEX REPLACE "Threads::Threads" "caffe2::Threads" content "${content}")
   file(WRITE ${FILENAME} "${content}")
 endif(REVERT)

cmake/MiscCheck.cmake

@@ -136,85 +136,6 @@ if(NOT MSVC)
   endif()
 endif()
 
-# ---[ If we are using msvc, set no warning flags
-# Note(jiayq): if you are going to add a warning flag, check if this is
-# totally necessary, and only add when you see fit. If it is needed due to
-# a third party library (like Protobuf), mention it in the comment as
-# "THIRD_PARTY_NAME related"
-# From https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/
-if(${CMAKE_CXX_COMPILER_ID} STREQUAL "MSVC")
-  add_compile_options(
-      ##########################################
-      # Protobuf related. Cannot remove.
-      # This is directly copied from
-      #     https://github.com/google/protobuf/blob/master/cmake/README.md
-      ##########################################
-      /wd4018 # 'expression' : signed/unsigned mismatch
-      /wd4065 # (3): switch with default but no case.
-      /wd4146 # unary minus operator applied to unsigned type, result still unsigned
-      /wd4244 # Conversion from 'type1' to 'type2', possible loss of data.
-      /wd4251 # 'identifier' : class 'type' needs to have dll-interface to be used by clients of class 'type2'
-      /wd4267 # Conversion from 'size_t' to 'type', possible loss of data.
-      /wd4305 # 'identifier' : truncation from 'type1' to 'type2'
-      /wd4355 # 'this' : used in base member initializer list
-      /wd4506 # (1): no definition for inline function. Protobuf related.
-      /wd4661 # No suitable definition provided for explicit template instantiation request
-      /wd4800 # 'type' : forcing value to bool 'true' or 'false' (performance warning)
-      /wd4996 # 'function': was declared deprecated
-      ##########################################
-      # Third party related. Cannot remove.
-      ##########################################
-      /wd4141 # (1): inline used twice. google benchmark related.
-      /wd4503 # (1): decorated name length exceeded, name was truncated.
-              #      Eigen related.
-      /wd4554 # (3): check operator precedence for possible error.
-              # Eigen related.
-      /wd4805 # (1): Unsafe mix of types in gtest/gtest.h. Gtest related.
-      ##########################################
-      # These are directly ATen related. However, several are covered by
-      # the above now. We leave them here for documentation purposes only.
-      #/wd4267 # Conversion from 'size_t' to 'type', possible loss of data.
-      /wd4522 # (3): 'class' : multiple assignment operators specified
-      /wd4838 # (1): conversion from 'type_1' to 'type_2' requires a
-              #      narrowing conversion
-      #/wd4305 # 'identifier' : truncation from 'type1' to 'type2'
-      #/wd4244 # Conversion from 'type1' to 'type2', possible loss of data.
-      /wd4190 # (1): 'identifier1' has C-linkage specified, but returns UDT
-              #      'identifier2' which is incompatible with C
-      /wd4101 # (3): 'identifier' : unreferenced local variable
-      #/wd4996 # (3): Use of deprecated POSIX functions. Since we develop
-      #        #      mainly on Linux, this is ignored.
-      /wd4275 # (2): non - DLL-interface classkey 'identifier' used as
-              #      base for DLL-interface classkey 'identifier'
-      ##########################################
-      # These are directly Caffe2 related. However, several are covered by
-      # protobuf now. We leave them here for documentation purposes only.
-      ##########################################
-      #/wd4018 # (3): Signed/unsigned mismatch. We've used it in many places
-      #        #      of the code and it would be hard to correct all.
-      #/wd4244 # (2/3/4): Possible loss of precision. Various cases where we
-      #        #      implicitly cast TIndex to int etc. Need cleaning.
-      #/wd4267 # (3): Conversion of size_t to smaller type. Same as 4244.
-      #/wd4996 # (3): Use of deprecated POSIX functions. Since we develop
-      #        #      mainly on Linux, this is ignored.
-      /wd4273 # (1): inconsistent dll linkage. This is related to the
-              #      caffe2 FLAGS_* definition using dllimport in header and
-              #      dllexport in cc file. The strategy is copied from gflags.
-  )
-
-  # Make sure windows.h does not include additional headers.
-  add_definitions("/DWIN32_LEAN_AND_MEAN")
-
-  # Make sure windef.h does not define max/min macros.
-  # Required by ATen among others.
-  add_definitions("/DNOMINMAX")
-
-  set(CMAKE_SHARED_LINKER_FLAGS
-      "${CMAKE_SHARED_LINKER_FLAGS} /ignore:4049 /ignore:4217 /ignore:4099")
-  set(CMAKE_EXE_LINKER_FLAGS
-      "${CMAKE_EXE_LINKER_FLAGS} /ignore:4049 /ignore:4217 /ignore:4099")
-endif()
-
 # ---[ If we are building on ios, or building with opengl support, we will
 # enable -mfpu=neon-fp16 for iOS Metal build. For Android, this fpu setting
 # is going to be done with android-cmake by setting

cmake/public/cuda.cmake

@@ -405,21 +405,6 @@ set_property(
     TARGET caffe2::nvrtc PROPERTY INTERFACE_INCLUDE_DIRECTORIES
     ${CUDA_INCLUDE_DIRS})
 
-# Note: in theory, we can add similar dependent library wrappers. For
-# now, Caffe2 only uses the above libraries, so we will only wrap
-# these.
-
-# Special care for windows platform: we know that 32-bit windows does not
-# support cuda.
-if(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
-  if(NOT (CMAKE_SIZEOF_VOID_P EQUAL 8))
-    message(FATAL_ERROR
-            "CUDA support not available with 32-bit windows. Did you "
-            "forget to set Win64 in the generator target?")
-    return()
-  endif()
-endif()
-
 # Add onnx namepsace definition to nvcc
 if(ONNX_NAMESPACE)
   list(APPEND CUDA_NVCC_FLAGS "-DONNX_NAMESPACE=${ONNX_NAMESPACE}")

cmake/public/threads.cmake

@@ -2,7 +2,6 @@ project(libshm C CXX)
 cmake_minimum_required(VERSION 3.18 FATAL_ERROR)
 
 set(TORCH_ROOT ${CMAKE_CURRENT_LIST_DIR}/../../../)
-include(${TORCH_ROOT}/cmake/public/threads.cmake)
 
 if(NOT LIBSHM_INSTALL_LIB_SUBDIR)
   set(LIBSHM_INSTALL_LIB_SUBDIR "lib" CACHE PATH "libshm install library directory")
@@ -34,6 +33,7 @@ target_link_libraries(shm PUBLIC torch)
 
 if(UNIX AND NOT APPLE)
   include(CheckLibraryExists)
+  find_package(Threads REQUIRED)
   # https://github.com/libgit2/libgit2/issues/2128#issuecomment-35649830
   check_library_exists(rt clock_gettime "time.h" NEED_LIBRT)
   if(NEED_LIBRT)
@@ -56,12 +56,12 @@ if(UNIX AND NOT APPLE)
     # site above though in case there was a reason we were testing
     # against clock_gettime. In principle, the choice of symbol you
     # test for shouldn't matter.
-    set(CMAKE_REQUIRED_LIBRARIES caffe2::Threads)
+    set(CMAKE_REQUIRED_LIBRARIES Threads::Threads)
     check_library_exists(rt shm_open "sys/mman.h" NEED_RT_AND_PTHREAD)
     unset(CMAKE_REQUIRED_LIBRARIES)
     if(NEED_RT_AND_PTHREAD)
       message(STATUS "Needs it, linking against pthread and rt")
-      target_link_libraries(shm PUBLIC rt caffe2::Threads)
+      target_link_libraries(shm PUBLIC rt Threads::Threads)
     endif()
   endif()
 endif()