Re: [PATCH v2 01/11] Introduce CMake support for configuring Git on Linux

> To make this a little less awkward, the Git for Windows project offers
> the `vs/master` branch which has a full Visual Studio solution generated
> and committed. This branch can therefore be used to tinker with Git in
> Visual Studio _without_ having to download the full Git for Windows SDK.
> Unfortunatly, that branch is auto-generated from Git for Windows'
> `master`. If a developer wants to tinker, say, with `pu`, they are out
> of luck.

> This is only the first step, and to make it easier to review, it only
> allows for configuring builds on the platform that is easiest to
> configure for: Linux.
>
> The CMake script checks whether the headers are present(eg. libgen.h),
> whether the functions are present(eg. memmem), whether the funtions work
> properly (eg. snprintf) and generate the required compile definitions
> for the platform. The script also searches for the required libraries,
> if it fails to find the required libraries the respective executables
> won't be built.(eg. If libcurl is not found then git-remote-http won't
> be built). This will help building Git easier.
>
> With a CMake script an out of source build of git is possible resulting
> in a clean source tree.

> Note: earlier endeavors on the Git mailing list to introduce CMake ended
> up in dead water. The primary reason for that was that reviewers
> _expected_ CMake support to fall out of maintenance, unless the
> contributor would promise to keep an eye on keeping CMake support up to
> date. However, in the meantime, support for automated testing has been
> introduced in Git's source code, and a later patch will modify the
> (still experimental) GitHub workflow to continually verify that CMake
> support is still complete. That will make maintenance reasonably easy.

> Note: this patch asks for the minimum version v3.14 of CMake (which is
> not all that old as of time of writing) because that is the first
> version to offer a platform-independent way to generate hardlinks as
> part of the build. This is needed to generate all those hardlinks for
> the built-in commands of Git.

> Instructions to run CMake:
>
> cmake `relative-path-to-srcdir` -DCMAKE_BUILD_TYPE=Release
>
> Possible build configurations(-DCMAKE_BUILD_TYPE) with corresponding
> compiler flags
> Debug : -g
> Release: -O3
> RelWithDebInfo : -O2 -g
> MinSizeRel : -Os
> empty(default) :
>
> NOTE: -DCMAKE_BUILD_TYPE is optional
>
> This process generates a Makefile.
> Then run `make` to build Git.
>
> NOTE: By default CMake uses Makefile as the build tool on Linux, to use
> another tool say `ninja` add this to the command line when configuring.
> `-G Ninja`

> Signed-off-by: Sibi Siddharthan <sibisiddharthan.github@gmail.com>
> ---
>  CMakeLists.txt | 528 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 528 insertions(+)
>  create mode 100644 CMakeLists.txt
>
> diff --git a/CMakeLists.txt b/CMakeLists.txt
> new file mode 100644
> index 00000000000..73703bd321f
> --- /dev/null
> +++ b/CMakeLists.txt
> @@ -0,0 +1,528 @@
> +#
> +#	Copyright (c) 2020 Sibi Siddharthan
> +#
> +
> +cmake_minimum_required(VERSION 3.14)
> +
> +#Parse GIT-VERSION-GEN to get the version
> +file(STRINGS ${CMAKE_SOURCE_DIR}/GIT-VERSION-GEN git_version REGEX "DEF_VER=v(.*)")
> +string(REPLACE "DEF_VER=v" "" git_version ${git_version})
> +string(REPLACE ".GIT" ".0" git_version ${git_version})#for building from a snapshot

> +set(git_SOURCES
> +	builtin/add.c builtin/am.c builtin/annotate.c builtin/apply.c
> +	builtin/archive.c builtin/bisect--helper.c builtin/blame.c
> +	builtin/branch.c builtin/bundle.c builtin/cat-file.c builtin/check-attr.c
> +	builtin/check-ignore.c builtin/check-mailmap.c builtin/check-ref-format.c
> +	builtin/checkout-index.c builtin/checkout.c builtin/clean.c
> +	builtin/clone.c builtin/column.c builtin/commit-tree.c
> +	builtin/commit.c builtin/commit-graph.c builtin/config.c
> +	builtin/count-objects.c builtin/credential.c builtin/describe.c
> +	builtin/diff-files.c builtin/diff-index.c builtin/diff-tree.c
> +	builtin/diff.c builtin/difftool.c builtin/env--helper.c
> +	builtin/fast-export.c builtin/fetch-pack.c builtin/fetch.c builtin/fmt-merge-msg.c
> +	builtin/for-each-ref.c builtin/fsck.c builtin/gc.c
> +	builtin/get-tar-commit-id.c builtin/grep.c builtin/hash-object.c
> +	builtin/help.c builtin/index-pack.c builtin/init-db.c
> +	builtin/interpret-trailers.c builtin/log.c builtin/ls-files.c
> +	builtin/ls-remote.c builtin/ls-tree.c builtin/mailinfo.c builtin/mailsplit.c
> +	builtin/merge.c builtin/merge-base.c builtin/merge-file.c builtin/merge-index.c
> +	builtin/merge-ours.c builtin/merge-recursive.c builtin/merge-tree.c
> +	builtin/mktag.c builtin/mktree.c builtin/multi-pack-index.c builtin/mv.c
> +	builtin/name-rev.c builtin/notes.c builtin/pack-objects.c builtin/pack-redundant.c
> +	builtin/pack-refs.c builtin/patch-id.c builtin/prune-packed.c builtin/prune.c
> +	builtin/pull.c builtin/push.c builtin/range-diff.c builtin/read-tree.c
> +	builtin/rebase.c builtin/receive-pack.c builtin/reflog.c builtin/remote.c
> +	builtin/remote-ext.c builtin/remote-fd.c builtin/repack.c builtin/replace.c
> +	builtin/rerere.c builtin/reset.c builtin/rev-list.c builtin/rev-parse.c
> +	builtin/revert.c builtin/rm.c builtin/send-pack.c builtin/shortlog.c
> +	builtin/show-branch.c builtin/show-index.c builtin/show-ref.c
> +	builtin/sparse-checkout.c builtin/stash.c builtin/stripspace.c
> +	builtin/submodule--helper.c builtin/symbolic-ref.c builtin/tag.c
> +	builtin/unpack-file.c builtin/unpack-objects.c builtin/update-index.c
> +	builtin/update-ref.c builtin/update-server-info.c builtin/upload-archive.c
> +	builtin/upload-pack.c builtin/var.c builtin/verify-commit.c builtin/verify-pack.c
> +	builtin/verify-tag.c builtin/worktree.c builtin/write-tree.c)