Re: [PATCH 7/8] cmake: support for building git on windows with msvc and clang.

> From: Sibi Siddharthan <sibisiddharthan.github@gmail.com>
> 
> This patch adds support for Visual Studio and Clang builds
> 
> The minimum required version of CMake is upgraded to 3.15 because
> this version offers proper support for Clang builds on Windows.
> 
> Libintl is not searched for when building with Visual Studio or Clang
> because there is no binary compatible version available yet.
> 
> NOTE: In the link options invalidcontinue.obj has to be included.
> The reason for this is because by default, Windows calls abort()'s
> instead of setting errno=EINVAL when invalid arguments are passed to
> standard functions.
> This commit explains it in detail:
> 4b623d80f73528a632576990ca51e34c333d5dd6
> 
> On Windows the default generator is Visual Studio,so for Visual Studio
> builds do this:
> 
> cmake `relative-path-to-srcdir`
> 
> NOTE: Visual Studio generator is a multi config generator, which means
> that Debug and Release builds can be done on the same build directory.
> 
> For Clang builds do this:
> 
> On bash
> CC=Clang cmake `relative-path-to-srcdir` -G Ninja
> 		-DCMAKE_BUILD_TYPE=[Debug or Release]
> 
> On cmd
> set CC=Clang
> cmake `relative-path-to-srcdir` -G Ninja
> 		-DCMAKE_BUILD_TYPE=[Debug or Release]
> 
> Signed-off-by: Sibi Siddharthan <sibisiddharthan.github@gmail.com>
> ---
>  CMakeLists.txt | 57 ++++++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 46 insertions(+), 11 deletions(-)
> 
> diff --git a/CMakeLists.txt b/CMakeLists.txt
> index d9eb1060390..5ad3a2557f7 100644
> --- a/CMakeLists.txt
> +++ b/CMakeLists.txt
> @@ -2,7 +2,7 @@
>  #	Copyright (c) 2020 Sibi Siddharthan
>  #
>  
> -cmake_minimum_required(VERSION 3.14)
> +cmake_minimum_required(VERSION 3.15)

>  
>  #Parse GIT-VERSION-GEN to get the version
>  file(STRINGS ${CMAKE_SOURCE_DIR}/GIT-VERSION-GEN git_version REGEX "DEF_VER=v(.*)")
> @@ -32,8 +32,11 @@ find_package(ZLIB REQUIRED)
>  find_package(CURL)
>  find_package(EXPAT)
>  find_package(Iconv)
> -find_package(Intl)
>  
> +#Don't use libintl on Windows Visual Studio and Clang builds
> +if(NOT (WIN32 AND (CMAKE_C_COMPILER_ID STREQUAL "MSVC" OR CMAKE_C_COMPILER_ID STREQUAL "Clang")))
> +	find_package(Intl)
> +endif()
>  
>  if(NOT Intl_FOUND)
>  	add_compile_definitions(NO_GETTEXT)
> @@ -61,7 +64,7 @@ if(NOT SH_EXE)
>  	message(FATAL_ERROR "sh interpreter was not found in your path, please install one. On Windows you can get it from here https://gitforwindows.org/")
>  endif()
>  
> -if(WIN32)
> +if(WIN32 AND NOT MSVC)#not required for visual studio builds
>  	find_program(WINDRES_EXE windres)
>  	if(NOT WINDRES_EXE)
>  		message(FATAL_ERROR "Install windres on Windows for resource files")
> @@ -73,6 +76,13 @@ if(NOT MSGFMT_EXE)
>  	message(WARNING "Text Translations won't be build")
>  endif()
>  
> +#Force all visual studio outputs to CMAKE_BINARY_DIR
> +if(CMAKE_C_COMPILER_ID STREQUAL "MSVC")
> +	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG ${CMAKE_BINARY_DIR})
> +	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_RELEASE ${CMAKE_BINARY_DIR})
> +	add_compile_options(/MP)
> +endif()
> +
>  #default behaviour
>  include_directories(${CMAKE_SOURCE_DIR})
>  add_compile_definitions(GIT_HOST_CPU="${CMAKE_SYSTEM_PROCESSOR}")
> @@ -110,6 +120,10 @@ endif()
>  
>  #Platform Specific
>  if(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
> +	if(CMAKE_C_COMPILER_ID STREQUAL "MSVC" OR CMAKE_C_COMPILER_ID STREQUAL "Clang")
> +		include_directories(compat/vcbuild/include)
> +		add_compile_definitions(_CRT_SECURE_NO_WARNINGS _CRT_NONSTDC_NO_DEPRECATE)