Add a simple example for using Clang as a cross compiler for MSVC

playground/clang_cross/msvc/ReadMe.txt

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+To cross compile for Windows in MSVC mode from Linux, you will require the following:
+* A partition with Windows installed (NTFS).
+* Visual Studio (Tested with 2017).
+* The Windows SDK.
+* lowntfs-3g file system driver.
+
+Make sure the Windows partition is mounted with "-t lowntfs-3g -o defaults,ignore_case,windows_names".
+This will allow Clang to find all headers and libraries referenced by scripts and headers, otherwise you will run into case sensitivity errors.
+
+Clang uses the following environment variables to detect the Visual Studio install: VCINSTALLDIR, VCToolsInstallDir, INCLUDE, LIB, LIBPATH
+I just copied these from the output of the "set" command in an MSVC command prompt on Windows and translated the paths to Linux paths.
+Notice how the semicolon is still used as a path separator.
+See "example_environment_linux.sh" for how my setup looks like.
+It expects the Windows partition to be mounted on /mnt/windows, with VS2017 installed and Windows 10 SDK 10.0.17763.0.

playground/clang_cross/msvc/example_environment_linux.sh

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+export VCINSTALLDIR="/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/"
+export VCToolsInstallDir="/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/"
+export INCLUDE="/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/atlmfc/include;/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/include;/mnt/windows/program files (x86)/windows kits/10/include/10.0.17763.0/ucrt;/mnt/windows/program files (x86)/windows kits/10/include/10.0.17763.0/shared;/mnt/windows/program files (x86)/windows kits/10/include/10.0.17763.0/um;/mnt/windows/program files (x86)/windows kits/10/include/10.0.17763.0/winrt;/mnt/windows/program files (x86)/windows kits/10/include/10.0.17763.0/cppwinrt"
+export LIB="/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/atlmfc/lib/x64;/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/lib/x64;/mnt/windows/program files (x86)/windows kits/10/lib/10.0.17763.0/ucrt/x64;/mnt/windows/program files (x86)/windows kits/10/lib/10.0.17763.0/um/x64"
+export LIBPATH="/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/atlmfc/lib/x64;/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/lib/x64;/mnt/windows/program files (x86)/microsoft visual studio/2017/community/vc/tools/msvc/14.16.27023/lib/x86/store/references;/mnt/windows/program files (x86)/windows kits/10/unionmetadata/10.0.17763.0;/mnt/windows/program files (x86)/windows kits/10/references/10.0.17763.0"

playground/clang_cross/msvc/hello.c

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+#include <Windows.h>
+
+int main(int argc, char* argv[])
+{
+	(void)argc;
+	(void)argv;
+
+	WriteConsole(GetStdHandle(STD_OUTPUT_HANDLE), "Hello world!\n", 13, NULL, NULL);
+
+	return 0;
+}

playground/clang_cross/msvc/wscript

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+#! /usr/bin/env python
+# encoding: utf-8
+# DragoonX6 2019
+
+# the following two variables are used by the target "waf dist"
+VERSION='0.0.1'
+APPNAME='hello_msvc'
+
+top = '.'
+
+from waflib.Configure import conf, ConfigurationContext
+from waflib.Options import OptionsContext
+
+def options(opt):
+	opt.load('clang_cross')
+
+def configure(conf):
+	conf.load('clang_cross')
+
+	if not conf.env.implib_PATTERN == '%s.lib':
+		conf.fatal('''clang is not configured to compile in msvc mode.
+Use flag '--clang-target-triple=x86_64-windows-msvc' to configure.
+On Windows you're likely to require running from an MSVC command prompt.
+On Linux you will need to have access to a Windows partition with VS installed, and the environment set up properly.
+See the ReadMe for more information.''')
+
+	conf.env.append_value('CFLAGS', conf.env.CFLAGS_CRT_MULTITHREADED_DLL)
+
+def build(bld):
+	bld.program(
+		source = 'hello.c',
+		target = 'hello_msvc')