msvc: support building Git using MS Visual C++

With this patch, Git can be built using the Microsoft toolchain, via:

	make MSVC=1 [DEBUG=1]

Third party libraries are built from source using the open source
"vcpkg" tool set. See https://github.com/Microsoft/vcpkg

On a first build, the vcpkg tools and the third party libraries are
automatically downloaded and built. DLLs for the third party libraries
are copied to the top-level (and t/helper) directory to facilitate
debugging. See compat/vcbuild/README.

A series of .bat files are invoked by the Makefile to find the location
of the installed version of Visual Studio and the associated compiler
tools (essentially replicating the environment setup performed by a
"Developer Command Prompt"). This should find the most recent VS2015 or
VS2017 installation. Output from these scripts are used by the Makefile
to define compiler and linker pathnames and -I and -L arguments.

The build produces .pdb files for both debug and release builds.

Note: This commit was squashed from an organic series of commits
developed between 2016 and 2018 in Git for Windows' `master` branch.
This combined commit eliminates the obsolete commits related to fetching
NuGet packages for third party libraries. It is difficult to use NuGet
packages for C/C++ sources because they may be built by earlier versions
of the MSVC compiler and have CRT version and linking issues.

Additionally, the C/C++ NuGet packages that we were using tended to not
be updated concurrently with the sources.  And in the case of cURL and
OpenSSL, this could expose us to security issues.

Helped-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>
Helped-by: Philip Oakley <philipoakley@iee.org>
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

7 files changed, 371 insertions, 5 deletions

diff --git a/compat/mingw.c b/compat/mingw.c
index d14d333..c063ae6 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2388,6 +2388,12 @@ static void maybe_redirect_std_handles(void)
 				  GENERIC_WRITE, FILE_FLAG_NO_BUFFERING);
 }
 
+#ifdef _MSC_VER
+#ifdef _DEBUG
+#include <crtdbg.h>
+#endif
+#endif
+
 /*
  * We implement wmain() and compile with -municode, which would
  * normally ignore main(), but we call the latter from the former
diff --git a/compat/vcbuild/.gitignore b/compat/vcbuild/.gitignore
new file mode 100644
index 0000000..8f8b794
--- /dev/null
+++ b/compat/vcbuild/.gitignore
@@ -0,0 +1,3 @@
+/vcpkg/
+/MSVC-DEFS-GEN
+/VCPKG-DEFS
diff --git a/compat/vcbuild/README b/compat/vcbuild/README
index 60fd873..b633e7d 100644
--- a/compat/vcbuild/README
+++ b/compat/vcbuild/README
@@ -1,3 +1,42 @@
+The Steps to Build Git with VS2015 or VS2017 from the command line.
+
+1. Install the "vcpkg" open source package manager and build essential
+   third-party libraries.  The steps for this have been captured in a
+   set of convenience scripts.  These can be run from a stock Command
+   Prompt or from an SDK bash window:
+
+   $ cd <repo_root>
+   $ ./compat/vcbuild/vcpkg_install.bat
+
+   The vcpkg tools and all of the third-party sources will be installed
+   in this folder:
+      <repo_root>/compat/vcbuild/vcpkg/
+
+   A file will be created with a set of Makefile macros pointing to a
+   unified "include", "lib", and "bin" directory (release and debug) for
+   all of the required packages.  This file will be included by the main
+   Makefile:
+      <repo_root>/compat/vcbuild/MSVC-DEFS-GEN
+
+2. OPTIONALLY copy the third-party *.dll and *.pdb files into the repo
+   root to make it easier to run and debug git.exe without having to
+   manipulate your PATH.  This is especially true for debug sessions in
+   Visual Studio.
+
+   Use ONE of the following forms which should match how you want to
+   compile git.exe.
+
+   $ ./compat/vcbuild/vcpkg_copy_packages.bat debug
+   $ ./compat/vcbuild/vcpkg_copy_packages.bat release
+
+3. Build git using MSVC from an SDK bash window using one of the
+   following commands:
+
+   $ make MSVC=1
+   $ make MSVC=1 DEBUG=1
+
+================================================================
+
 The Steps of Build Git with VS2008
 
 1. You need the build environment, which contains the Git dependencies
diff --git a/compat/vcbuild/find_vs_env.bat b/compat/vcbuild/find_vs_env.bat
new file mode 100644
index 0000000..40194dd
--- /dev/null
+++ b/compat/vcbuild/find_vs_env.bat
@@ -0,0 +1,168 @@
+@ECHO OFF
+REM ================================================================
+REM You can use either GCC (the default) or MSVC to build git
+REM using the GIT-SDK command line tools.
+REM        $ make
+REM        $ make MSVC=1
+REM
+REM GIT-SDK BASH windows inherit environment variables with all of
+REM the bin/lib/include paths for GCC.  It DOES NOT inherit values
+REM for the corresponding MSVC tools.
+REM
+REM During normal (non-git) Windows development, you launch one
+REM of the provided "developer command prompts" to set environment
+REM variables for the MSVC tools.
+REM
+REM Therefore, to allow MSVC command line builds of git from BASH
+REM and MAKE, we must blend these two different worlds.  This script
+REM attempts to do that.
+REM ================================================================
+REM This BAT file starts in a plain (non-developer) command prompt,
+REM searches for the "best" commmand prompt setup script, installs
+REM it into the current CMD process, and exports the various MSVC
+REM environment variables for use by MAKE.
+REM
+REM The output of this script should be written to a make "include
+REM file" and referenced by the top-level Makefile.
+REM
+REM See "config.mak.uname" (look for compat/vcbuild/MSVC-DEFS-GEN).
+REM ================================================================
+REM The provided command prompts are custom to each VS release and
+REM filled with lots of internal knowledge (such as Registry settings);
+REM even their names vary by release, so it is not appropriate for us
+REM to look inside them.  Rather, just run them in a subordinate
+REM process and extract the settings we need.
+REM ================================================================
+REM
+REM Current (VS2017 and beyond)
+REM -------------------
+REM Visual Studio 2017 introduced a new installation layout and
+REM support for side-by-side installation of multiple versions of
+REM VS2017.  Furthermore, these can all coexist with installations
+REM of previous versions of VS (which have a completely different
+REM layout on disk).
+REM
+REM VS2017 Update 2 introduced a "vswhere.exe" command:
+REM https://github.com/Microsoft/vswhere
+REM https://blogs.msdn.microsoft.com/heaths/2017/02/25/vswhere-available/
+REM https://blogs.msdn.microsoft.com/vcblog/2017/03/06/finding-the-visual-c-compiler-tools-in-visual-studio-2017/
+REM
+REM VS2015
+REM ------
+REM Visual Studio 2015 uses the traditional VcVarsAll.
+REM
+REM Earlier Versions
+REM ----------------
+REM Currently unsupported.
+REM
+REM ================================================================
+REM Note: Throughout this script we use "dir <path> && <cmd>" rather
+REM than "if exist <path>" because of script problems with pathnames
+REM containing spaces.
+REM ================================================================
+
+REM Sanitize PATH to prevent git-sdk paths from confusing "wmic.exe"
+REM (called internally in some of the system BAT files).
+SET PATH=%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;
+
+REM ================================================================
+
+:current
+   SET vs_where=C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe
+   dir "%vs_where%" >nul 2>nul && GOTO have_vs_where
+   GOTO not_2017
+
+:have_vs_where
+   REM Try to use VsWhere to get the location of VsDevCmd.
+
+   REM Keep VsDevCmd from cd'ing away.
+   SET VSCMD_START_DIR=.
+
+   REM Get the root of the VS product installation.
+   FOR /F "usebackq tokens=*" %%i IN (`"%vs_where%" -latest -requires Microsoft.VisualStudio.Workload.NativeDesktop -property installationPath`) DO @SET vs_ip=%%i
+
+   SET vs_devcmd=%vs_ip%\Common7\Tools\VsDevCmd.bat
+   dir "%vs_devcmd%" >nul 2>nul && GOTO have_vs_devcmd
+   GOTO not_2017
+
+:have_vs_devcmd
+   REM Use VsDevCmd to setup the environment of this process.
+   REM Setup CL for building 64-bit apps using 64-bit tools.
+   @call "%vs_devcmd%" -no_logo -arch=x64 -host_arch=x64
+
+   SET tgt=%VSCMD_ARG_TGT_ARCH%
+
+   SET mn=%VCToolsInstallDir%
+   SET msvc_includes=-I"%mn%INCLUDE"
+   SET msvc_libs=-L"%mn%lib\%tgt%"
+   SET msvc_bin_dir=%mn%bin\Host%VSCMD_ARG_HOST_ARCH%\%tgt%
+
+   SET sdk_dir=%WindowsSdkDir%
+   SET sdk_ver=%WindowsSDKVersion%
+   SET si=%sdk_dir%Include\%sdk_ver%
+   SET sdk_includes=-I"%si%ucrt" -I"%si%um" -I"%si%shared"
+   SET sl=%sdk_dir%lib\%sdk_ver%
+   SET sdk_libs=-L"%sl%ucrt\%tgt%" -L"%sl%um\%tgt%"
+
+   SET vs_ver=%VisualStudioVersion%
+
+   GOTO print_vars
+
+REM ================================================================
+
+:not_2017
+   REM See if VS2015 is installed.
+
+   SET vs_2015_bat=C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat
+   dir "%vs_2015_bat%" >nul 2>nul && GOTO have_vs_2015
+   GOTO not_2015
+
+:have_vs_2015
+   REM Use VcVarsAll like the "x64 Native" command prompt.
+   REM Setup CL for building 64-bit apps using 64-bit tools.
+   @call "%vs_2015_bat%" amd64
+
+   REM Note that in VS2015 they use "x64" in some contexts and "amd64" in others.
+   SET mn=C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\
+   SET msvc_includes=-I"%mn%INCLUDE"
+   SET msvc_libs=-L"%mn%lib\amd64"
+   SET msvc_bin_dir=%mn%bin\amd64
+
+   SET sdk_dir=%WindowsSdkDir%
+   SET sdk_ver=%WindowsSDKVersion%
+   SET si=%sdk_dir%Include\%sdk_ver%
+   SET sdk_includes=-I"%si%ucrt" -I"%si%um" -I"%si%shared" -I"%si%winrt"
+   SET sl=%sdk_dir%lib\%sdk_ver%
+   SET sdk_libs=-L"%sl%ucrt\x64" -L"%sl%um\x64"
+
+   SET vs_ver=%VisualStudioVersion%
+
+   GOTO print_vars
+
+REM ================================================================
+
+:not_2015
+   echo "ERROR: unsupported VS version (older than VS2015)" >&2
+   EXIT /B 1
+
+REM ================================================================
+
+:print_vars
+   REM Dump the essential vars to stdout to allow the main
+   REM Makefile to include it.  See config.mak.uname.
+   REM Include DOS-style and BASH-style path for bin dir.
+
+   echo msvc_bin_dir=%msvc_bin_dir%
+   SET X1=%msvc_bin_dir:C:=/C%
+   SET X2=%X1:\=/%
+   echo msvc_bin_dir_msys=%X2%
+
+   echo msvc_includes=%msvc_includes%
+   echo msvc_libs=%msvc_libs%
+
+   echo sdk_includes=%sdk_includes%
+   echo sdk_libs=%sdk_libs%
+
+   echo vs_ver=%vs_ver%
+
+   EXIT /B 0
diff --git a/compat/vcbuild/scripts/clink.pl b/compat/vcbuild/scripts/clink.pl
index a87d0da..c7b021b 100755
--- a/compat/vcbuild/scripts/clink.pl
+++ b/compat/vcbuild/scripts/clink.pl
@@ -12,32 +12,62 @@
 use strict;
 my @args = ();
 my @cflags = ();
+my @lflags = ();
 my $is_linking = 0;
+my $is_debug = 0;
 while (@ARGV) {
 	my $arg = shift @ARGV;
-	if ("$arg" =~ /^-[DIMGO]/) {
+	if ("$arg" eq "-DDEBUG") {
+	    # Some vcpkg-based libraries have different names for release
+	    # and debug versions.  This hack assumes that -DDEBUG comes
+	    # before any "-l*" flags.
+	    $is_debug = 1;
+	}
+	if ("$arg" =~ /^-[DIMGOZ]/) {
 		push(@cflags, $arg);
 	} elsif ("$arg" eq "-o") {
 		my $file_out = shift @ARGV;
 		if ("$file_out" =~ /exe$/) {
 			$is_linking = 1;
+			# Create foo.exe and foo.pdb
 			push(@args, "-OUT:$file_out");
 		} else {
+			# Create foo.o and foo.o.pdb
 			push(@args, "-Fo$file_out");
+			push(@args, "-Fd$file_out.pdb");
 		}
 	} elsif ("$arg" eq "-lz") {
+	    if ($is_debug) {
+		push(@args, "zlibd.lib");
+	    } else{
 		push(@args, "zlib.lib");
+	    }
 	} elsif ("$arg" eq "-liconv") {
-		push(@args, "iconv.lib");
+		push(@args, "libiconv.lib");
 	} elsif ("$arg" eq "-lcrypto") {
 		push(@args, "libeay32.lib");
 	} elsif ("$arg" eq "-lssl") {
 		push(@args, "ssleay32.lib");
 	} elsif ("$arg" eq "-lcurl") {
-		push(@args, "libcurl.lib");
+		my $lib = "";
+		# Newer vcpkg definitions call this libcurl_imp.lib; Do we
+		# need to use that instead?
+		foreach my $flag (@lflags) {
+			if ($flag =~ /^-LIBPATH:(.*)/) {
+				foreach my $l ("libcurl_imp.lib", "libcurl.lib") {
+					if (-f "$1/$l") {
+						$lib = $l;
+						last;
+					}
+				}
+			}
+		}
+		push(@args, $lib);
+	} elsif ("$arg" eq "-lexpat") {
+		push(@args, "expat.lib");
 	} elsif ("$arg" =~ /^-L/ && "$arg" ne "-LTCG") {
 		$arg =~ s/^-L/-LIBPATH:/;
-		push(@args, $arg);
+		push(@lflags, $arg);
 	} elsif ("$arg" =~ /^-R/) {
 		# eat
 	} else {
@@ -45,10 +75,11 @@ while (@ARGV) {
 	}
 }
 if ($is_linking) {
+	push(@args, @lflags);
 	unshift(@args, "link.exe");
 } else {
 	unshift(@args, "cl.exe");
 	push(@args, @cflags);
 }
-#printf("**** @args\n");
+printf(STDERR "**** @args\n\n\n") if (!defined($ENV{'QUIET_GEN'}));
 exit (system(@args) != 0);
diff --git a/compat/vcbuild/vcpkg_copy_dlls.bat b/compat/vcbuild/vcpkg_copy_dlls.bat
new file mode 100644
index 0000000..13661c1
--- /dev/null
+++ b/compat/vcbuild/vcpkg_copy_dlls.bat
@@ -0,0 +1,39 @@
+@ECHO OFF
+REM ================================================================
+REM This script is an optional step. It copies the *.dll and *.pdb
+REM files (created by vcpkg_install.bat) into the top-level directory
+REM of the repo so that you can type "./git.exe" and find them without
+REM having to fixup your PATH.
+REM
+REM NOTE: Because the names of some DLL files change between DEBUG and
+REM NOTE: RELEASE builds when built using "vcpkg.exe", you will need
+REM NOTE: to copy up the corresponding version.
+REM ================================================================
+
+	SETLOCAL EnableDelayedExpansion
+
+	@FOR /F "delims=" %%D IN ("%~dp0") DO @SET cwd=%%~fD
+	cd %cwd%
+
+	SET arch=x64-windows
+	SET inst=%cwd%vcpkg\installed\%arch%
+
+	IF [%1]==[release] (
+		echo Copying RELEASE mode DLLs to repo root...
+	) ELSE IF [%1]==[debug] (
+		SET inst=%inst%\debug
+		echo Copying DEBUG mode DLLs to repo root...
+	) ELSE (
+		echo ERROR: Invalid argument.
+		echo Usage: %~0 release
+		echo Usage: %~0 debug
+		EXIT /B 1
+	)
+
+	xcopy /e/s/v/y %inst%\bin\*.dll ..\..\
+	xcopy /e/s/v/y %inst%\bin\*.pdb ..\..\
+
+	xcopy /e/s/v/y %inst%\bin\*.dll ..\..\t\helper\
+	xcopy /e/s/v/y %inst%\bin\*.pdb ..\..\t\helper\
+
+	EXIT /B 0
diff --git a/compat/vcbuild/vcpkg_install.bat b/compat/vcbuild/vcpkg_install.bat
new file mode 100644
index 0000000..ebd0bad
--- /dev/null
+++ b/compat/vcbuild/vcpkg_install.bat
@@ -0,0 +1,80 @@
+@ECHO OFF
+REM ================================================================
+REM This script installs the "vcpkg" source package manager and uses
+REM it to build the third-party libraries that git requires when it
+REM is built using MSVC.
+REM
+REM [1] Install VCPKG.
+REM     [a] Create <root>/compat/vcbuild/vcpkg/
+REM     [b] Download "vcpkg".
+REM     [c] Compile using the currently installed version of VS.
+REM     [d] Create <root>/compat/vcbuild/vcpkg/vcpkg.exe
+REM
+REM [2] Install third-party libraries.
+REM     [a] Download each (which may also install CMAKE).
+REM     [b] Compile in RELEASE mode and install in:
+REM         vcpkg/installed/<arch>/{bin,lib}
+REM     [c] Compile in DEBUG mode and install in:
+REM         vcpkg/installed/<arch>/debug/{bin,lib}
+REM     [d] Install headers in:
+REM         vcpkg/installed/<arch>/include
+REM
+REM [3] Create a set of MAKE definitions for the top-level
+REM     Makefile to allow "make MSVC=1" to find the above
+REM     third-party libraries.
+REM     [a] Write vcpkg/VCPGK-DEFS
+REM
+REM https://blogs.msdn.microsoft.com/vcblog/2016/09/19/vcpkg-a-tool-to-acquire-and-build-c-open-source-libraries-on-windows/
+REM https://github.com/Microsoft/vcpkg
+REM https://vcpkg.readthedocs.io/en/latest/
+REM ================================================================
+
+	SETLOCAL EnableDelayedExpansion
+
+	@FOR /F "delims=" %%D IN ("%~dp0") DO @SET cwd=%%~fD
+	cd %cwd%
+
+	dir vcpkg\vcpkg.exe >nul 2>nul && GOTO :install_libraries
+
+	echo Fetching vcpkg in %cwd%vcpkg
+	git.exe clone https://github.com/Microsoft/vcpkg vcpkg
+	IF ERRORLEVEL 1 ( EXIT /B 1 )
+
+	cd vcpkg
+	echo Building vcpkg
+	powershell -exec bypass scripts\bootstrap.ps1
+	IF ERRORLEVEL 1 ( EXIT /B 1 )
+
+	echo Successfully installed %cwd%vcpkg\vcpkg.exe
+
+:install_libraries
+	SET arch=x64-windows
+
+	echo Installing third-party libraries...
+	FOR %%i IN (zlib expat libiconv openssl libssh2 curl) DO (
+	    cd %cwd%vcpkg
+	    IF NOT EXIST "packages\%%i_%arch%" CALL :sub__install_one %%i
+	    IF ERRORLEVEL 1 ( EXIT /B 1 )
+	)
+
+:install_defines
+	cd %cwd%
+	SET inst=%cwd%vcpkg\installed\%arch%
+
+	echo vcpkg_inc=-I"%inst%\include">VCPKG-DEFS
+	echo vcpkg_rel_lib=-L"%inst%\lib">>VCPKG-DEFS
+	echo vcpkg_rel_bin="%inst%\bin">>VCPKG-DEFS
+	echo vcpkg_dbg_lib=-L"%inst%\debug\lib">>VCPKG-DEFS
+	echo vcpkg_dbg_bin="%inst%\debug\bin">>VCPKG-DEFS
+
+	EXIT /B 0
+
+
+:sub__install_one
+	echo     Installing package %1...
+
+	.\vcpkg.exe install %1:%arch%
+	IF ERRORLEVEL 1 ( EXIT /B 1 )
+
+	echo     Finished %1
+	goto :EOF