[vcpkg] Add support to pull from git-lfs

[ahojnnes]

Without this PR, checking out sources from a git repository with git-lfs enabled fails with the following error:

Use `git lfs logs last` to view the log.
error: external filter 'git-lfs filter-process' failed
fatal: <... git-lfs file path ...>: smudge filter lfs failed

[PhoebeHui]

Related to #18570.

[ahojnnes]

Yes, thanks @PhoebeHui. In the older PR, I mentioned that the issue was fixed but then I realized it actually isn’t, so I fixed it here.

[PhoebeHui]

LGTM, we will ask other team member to take a look again。

[BillyONeal]

How common is it for the git bundled with most Linux distros to include git-lfs support?

Do you have any ports which fail without this change but don't fail afterwards? We shouldn't add random support here without a test case.

[ahojnnes]

I have a custom portfile against a Microsoft internal repository with git-lfs enabled. Without this patch here, I am unable to checkout and build the code. I don’t know about a public repository but I could setup a mock repo to reproduce the issue. If you have an alternative suggestion to solve the issue, I’d be happy to hear. Otherwise I am also happy to add test coverage for this fix, if you can give me a pointer to where I should get started with that. Thanks.

[JackBoosY]

Ping @BillyONeal for reply.

[BillyONeal]

I have a custom portfile against a Microsoft internal repository with git-lfs enabled. Without this patch here, I am unable to checkout and build the code. I don’t know about a public repository but I could setup a mock repo to reproduce the issue. If you have an alternative suggestion to solve the issue, I’d be happy to hear. Otherwise I am also happy to add test coverage for this fix, if you can give me a pointer to where I should get started with that. Thanks.

Without a public user it's concerning to add since it adds a new dependency of vcpkg which ports may depend on by accident and thus blow up in users' face if lfs is not ~always installed on all the *nixes.

[strega-nil-ms]

I'm not against this; I think it's entirely reasonable, and it doesn't break anybody. My questions are:

• what happens with LFS data when the origin remote changes?
• what happens when git-lfs isn't installed?
• does LFS trigger trigger automatically, or is it something that's perhaps triggered by the build system
  • in other words, if you install a port that requires git-lfs, will it be obvious you need to install git-lfs or will it just fail in a weird way

[BillyONeal]

I'm not against this; I think it's entirely reasonable, and it doesn't break anybody.

+1. I just realized my replies could have been understood to mean that I was opposed to this. Like @strega-nil I'm mostly ensuring we understand the consequences more than worried about the change itself.

[strega-nil-ms]

unmarking requires:vcpkg-team-review until the author gets back to us.

[ahojnnes]

To reply to @strega-nil-ms questions above in order:

1. Unless I missed something, each call to vcpkg_from_git will happily overwrite the existing origin URL with whatever URL was provided on the caller side. This assumes the git repository was already checked out using something like --editable? Not sure under which other scenarios, vcpkg would not check out a complete new clone of the repo?
2. If git-lfs is not installed, there shouldn't be any noticeable difference.
3. git-lfs will be used automatically, if the repo requires it.

[JackBoosY]

Ping @strega-nil-ms for response.

[BillyONeal]

2. If git-lfs is not installed, there shouldn't be any noticeable difference.

Is it documented this way or have you actually tried it?

3. git-lfs will be used automatically, if the repo requires it.

I don't think you answered the question. Note: "in other words, if you install a port that requires git-lfs, will it be obvious you need to install git-lfs or will it just fail in a weird way"

[JackBoosY]

Ping for response.

[pavel-pokutnev]

I have the same issue. Just want to confirm that this patch is solving it on my side.

[JackBoosY]

Convert this PR to draft since there is no response for a long time.

[JackBoosY]

Please temporary close this PR if you don't have spare time to finish it.