vcpkg: get MSVC dependencies with vcpkg rather than nuget

Dependencies such as cURL and OpenSSL are necessary to build and run
Git. Previously, we obtained those dependencies by fetching NuGet
packages.

However, it is notoriously hard to keep NuGet packages of C/C++
libraries up-to-date, as the toolsets for different Visual Studio
versions are different, and the NuGet packages would have to ship them
all.

That is the reason why the NuGet packages we use are quite old, and even
insecure in the case of cURL and OpenSSL (the versions contain known
security flaws that have been addressed by later versions for which no
NuGet packages are available).

The better way to handle this situation is to use the vcpkg system:
https://github.com/Microsoft/vcpkg

The idea is that a single Git repository contains enough supporting
files to build up-to-date versions of a large number of Open Source
libraries on demand, including cURL and OpenSSL.

We integrate this system via four new .bat files to

1) initialize the vcpkg system,
2) build the packages,
4) set up Git's Makefile system to find the build artifacts, and
3) copy the artifacts into the top-level directory

Signed-off-by: Jeff Hostetler <[email protected]>
Signed-off-by: Johannes Schindelin <[email protected]>

Author: jeffhostetler

.gitignore

@@ -1,7 +1,6 @@
 /GIT-BUILD-OPTIONS
 /GIT-CFLAGS
 /GIT-LDFLAGS
-/GIT-MSVC-GEN
 /GIT-PREFIX
 /GIT-PERL-DEFINES
 /GIT-PERL-HEADER

Makefile

@@ -2756,8 +2756,6 @@ install: all
 	$(INSTALL) -m 644 $(SCRIPT_LIB) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
 	$(INSTALL) $(install_bindir_programs) '$(DESTDIR_SQ)$(bindir_SQ)'
 ifdef MSVC
-	$(INSTALL) compat/vcbuild/GEN.DEPS/bin/*.dll '$(DESTDIR_SQ)$(bindir_SQ)'
-	$(INSTALL) compat/vcbuild/GEN.DEPS/bin/*.pdb '$(DESTDIR_SQ)$(bindir_SQ)'
 	# We DO NOT install the individual foo.o.pdb files because they
 	# have already been rolled up into the exe's pdb file.
 	# We DO NOT have pdb files for the builtin commands (like git-status.exe)
@@ -2980,9 +2978,15 @@ endif
 ifdef MSVC
 	$(RM) $(patsubst %.o,%.o.pdb,$(OBJECTS))
 	$(RM) $(patsubst %.exe,%.pdb,$(OTHER_PROGRAMS))
+	$(RM) $(patsubst %.exe,%.iobj,$(OTHER_PROGRAMS))
+	$(RM) $(patsubst %.exe,%.ipdb,$(OTHER_PROGRAMS))
 	$(RM) $(patsubst %.exe,%.pdb,$(PROGRAMS))
+	$(RM) $(patsubst %.exe,%.iobj,$(PROGRAMS))
+	$(RM) $(patsubst %.exe,%.ipdb,$(PROGRAMS))
 	$(RM) $(patsubst %.exe,%.pdb,$(TEST_PROGRAMS))
-	$(RM) GIT-MSVC-GEN
+	$(RM) $(patsubst %.exe,%.iobj,$(TEST_PROGRAMS))
+	$(RM) $(patsubst %.exe,%.ipdb,$(TEST_PROGRAMS))
+	$(RM) compat/vcbuild/MSVC-DEFS-GEN
 endif
 
 .PHONY: all install profile-clean cocciclean clean strip

compat/vcbuild/.gitignore

@@ -1 +1,3 @@
-GEN.*
+/vcpkg/
+/MSVC-DEFS-GEN
+/VCPKG-DEFS

compat/vcbuild/README

@@ -1,3 +1,54 @@
+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 libaries.  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
+
+================================================================
+
+Alternatively, run `make MSVC=1 vcxproj` and then load the generated
+git.sln in Visual Studio. The initial build will install the vcpkg
+system and build the dependencies automatically. This will take a while.
+
+Note that this will automatically add and commit the generated
+.sln and .vcxproj files to the repo.  You may want to drop this
+commit before submitting a Pull Request....
+
+Or maybe we should put the .sln/.vcxproj files in the .gitignores
+and not do this.  I'm not sure.
+
+================================================================
 The Steps of Build Git with VS2008
 
 1. You need the build environment, which contains the Git dependencies