From 3027e783b1cba83546dab50610a9d244bc2632b2 Mon Sep 17 00:00:00 2001
From: Sacha <xsacha@gmail.com>
Date: Tue, 2 Apr 2019 13:15:10 -0700
Subject: [PATCH] Fix multi-configuration on Windows CMake (CUDA) (#18548)

Summary:
Multiple configurations is the default (eg. Release;Debug) on Windows and this check always broke this configuration as CMAKE_BUILD_TYPE was not set. The workaround was to always set CMAKE_BUILD_TYPE to Debug or Release, which was very unfortunate.

The correct method is to use generator expressions that expand depending on the current CONFIG being processed.

Side note: Anywhere else CMAKE_BUILD_TYPE is checked should probably be fixed too.
Note that the CMakeLists.txt forces it in to Release mode. However, I came across this error when importing the prebuilt Config in to another project, where CMAKE_BUILD_TYPE was not set.

> 3>CMake Error at pre_built/pytorch-1.0.1/share/cmake/Caffe2/public/cuda.cmake:380 (message):
> 3>  Unknown cmake build type:

Proper support for configurations would mean we can build debug and release at the same time and as you can see, it is less CMake code.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18548

Differential Revision: D14730790

Pulled By: ezyang

fbshipit-source-id: 70ae16832870d742c577c34a50ec7564c3da0afb
---
 cmake/public/cuda.cmake | 16 +++-------------
 torch/CMakeLists.txt    |  6 ------
 2 files changed, 3 insertions(+), 19 deletions(-)

diff --git a/cmake/public/cuda.cmake b/cmake/public/cuda.cmake
index 43665df..a4d87e9 100644
--- a/cmake/public/cuda.cmake
+++ b/cmake/public/cuda.cmake
@@ -364,20 +364,10 @@ endif()
 
 # Debug and Release symbol support
 if (MSVC)
-  if ((${CMAKE_BUILD_TYPE} MATCHES "Release") OR (${CMAKE_BUILD_TYPE} MATCHES "RelWithDebInfo") OR (${CMAKE_BUILD_TYPE} MATCHES "MinSizeRel"))
-    if (${CAFFE2_USE_MSVC_STATIC_RUNTIME})
-      list(APPEND CUDA_NVCC_FLAGS "-Xcompiler" "-MT")
-    else()
-      list(APPEND CUDA_NVCC_FLAGS "-Xcompiler" "-MD")
-    endif()
-  elseif(${CMAKE_BUILD_TYPE} MATCHES "Debug")
-    if (${CAFFE2_USE_MSVC_STATIC_RUNTIME})
-      list(APPEND CUDA_NVCC_FLAGS "-Xcompiler" "-MTd")
-    else()
-      list(APPEND CUDA_NVCC_FLAGS "-Xcompiler" "-MDd")
-    endif()
+  if (${CAFFE2_USE_MSVC_STATIC_RUNTIME})
+    list(APPEND CUDA_NVCC_FLAGS "-Xcompiler" "-MT$<$<CONFIG:Debug>:d>")
   else()
-    message(FATAL_ERROR "Unknown cmake build type: " ${CMAKE_BUILD_TYPE})
+    list(APPEND CUDA_NVCC_FLAGS "-Xcompiler" "-MD$<$<CONFIG:Debug>:d>")
   endif()
 elseif (CUDA_DEVICE_DEBUG)
   list(APPEND CUDA_NVCC_FLAGS "-g" "-G")  # -G enables device code debugging symbols
diff --git a/torch/CMakeLists.txt b/torch/CMakeLists.txt
index 7da46b6..6cd237f 100644
--- a/torch/CMakeLists.txt
+++ b/torch/CMakeLists.txt
@@ -270,12 +270,6 @@ target_compile_definitions(torch PUBLIC _THP_CORE)
 
 # until they can be unified, keep these lists synced with setup.py
 if(MSVC)
-  if (${CMAKE_BUILD_TYPE} MATCHES "Debug")
-    set (MSVC_RUNTIME_LIBRARY_FLAG "/MDd")
-  else()
-    set (MSVC_RUNTIME_LIBRARY_FLAG "/MD")
-  endif()
-
   target_compile_options(torch PUBLIC
     ${MSVC_RUNTIME_LIBRARY_OPTION}
     /Z7
-- 
2.7.4