[External] Add a patching mechanism to external libraries

Also using this to fix the DXC with VS2019.2

Related work item: Github #49

CI/AzurePipelines/ContinuousBuild.yml

@@ -2,6 +2,11 @@ steps:
 - bash: eval '$(installCommand)'
   displayName: 'Install'
 
+- script: |
+    git config --global user.email "[email protected]"
+    git config --global user.name "Dummy Name"
+  displayName: 'Config git'
+
 - task: PythonScript@0
   displayName: 'Build'
   inputs:

External/CMakeLists.txt

@@ -38,11 +38,23 @@ function(UpdateExternalLib name url rev)
     endif()
 endfunction()
 
+function(ApplyPatch name patch)
+    set(external_folder "${SC_ROOT_DIR}/External")
+    set(external_lib_folder "${external_folder}/${name}")
+
+    execute_process(COMMAND "${git_executable}" "apply" "--check" "--ignore-space-change" "${patch}" WORKING_DIRECTORY ${external_lib_folder} RESULT_VARIABLE checkout_err)
+    if(NOT checkout_err)
+        message(STATUS "Applying ${patch}...")
+        execute_process(COMMAND "${git_executable}" "am" "--ignore-space-change" "${patch}" WORKING_DIRECTORY ${external_lib_folder})
+    endif()
+endfunction()
+
 UpdateExternalLib("cxxopts" "https://github.com/jarro2783/cxxopts.git" ${cxxopts_REV})
 UpdateExternalLib("googletest" "https://github.com/google/googletest.git" ${googletest_REV})
 UpdateExternalLib("SPIRV-Headers" "https://github.com/KhronosGroup/SPIRV-Headers.git" ${SPIRV_Headers_REV})
 UpdateExternalLib("SPIRV-Tools" "https://github.com/KhronosGroup/SPIRV-Tools.git" ${SPIRV_Tools_REV})
 UpdateExternalLib("DirectXShaderCompiler" "https://github.com/Microsoft/DirectXShaderCompiler.git" ${DirectXShaderCompiler_REV})
+ApplyPatch("DirectXShaderCompiler" "${CMAKE_CURRENT_SOURCE_DIR}/Patches/DirectXShaderCompiler/0001-Fix-the-compiling-problem-on-VS2019.2.patch")
 UpdateExternalLib("SPIRV-Cross" "https://github.com/KhronosGroup/SPIRV-Cross.git" ${SPIRV_Cross_REV})
 
 set(INSTALL_GTEST OFF CACHE BOOL "" FORCE)

External/Patches/DirectXShaderCompiler/0001-Fix-the-compiling-problem-on-VS2019.2.patch

@@ -0,0 +1,25 @@
+From 895b1301afea91017500a82dd9d709d9941d1abc Mon Sep 17 00:00:00 2001
+From: Minmin Gong <[email protected]>
+Date: Wed, 28 Aug 2019 22:52:12 -0700
+Subject: [PATCH] Fix the compiling problem on VS2019.2
+
+---
+ utils/TableGen/AsmWriterEmitter.cpp | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/utils/TableGen/AsmWriterEmitter.cpp b/utils/TableGen/AsmWriterEmitter.cpp
+index 8163f681..4372420d 100644
+--- a/utils/TableGen/AsmWriterEmitter.cpp
++++ b/utils/TableGen/AsmWriterEmitter.cpp
+@@ -763,7 +763,7 @@ static unsigned CountNumOperands(StringRef AsmString, unsigned Variant) {
+ namespace {
+ struct AliasPriorityComparator {
+   typedef std::pair<CodeGenInstAlias *, int> ValueType;
+-  bool operator()(const ValueType &LHS, const ValueType &RHS) {
++  bool operator()(const ValueType &LHS, const ValueType &RHS) const {
+     if (LHS.second ==  RHS.second) {
+       // We don't actually care about the order, but for consistency it
+       // shouldn't depend on pointer comparisons.
+-- 
+2.17.1.windows.2
+