[build] use WorkingDirectory for <GitBlame/>

[jonathanpeppers]

Downstream in monodroid, I'm getting a build failure such as:

/usr/bin/git blame "/full/path/to/external/xamarin-android/Configuration.props"
XAVersionInfo.targets(53,5): error MSB6006: "git" exited with code 128.
XAVersionInfo.targets(61,5): error MSB4044: The "GitCommitsInRange" task was not given a value for the required parameter "StartCommit".

If I run the git command manually:

fatal: not a git repository (or any of the parent directories): .git

It seems we shouldn't be using a full path here, but use
WorkingDirectory instead? Maybe it will not work if
xamarin-android is a submodule?

This has somehow been working in the past, so perhaps my version of
git is the cause?

$ git --version
git version 2.17.1 (Apple Git-112)

[jonathanpeppers]

Oh apparently someone else had this problem: #2574

[jonathanpeppers]

Don't know what happened to the build...

06:15:25 (_BuildAndroidSqlite target) -> 
06:15:25   /Users/builder/jenkins/workspace/xamarin-android-pr-builder-release/xamarin-android/external/sqlite/dist/sqlite3.c(33031,9): error G3127DA5A: use of undeclared identifier 'ANDROID_FDSAN_OWNER_TYPE_SQLITE'; did you mean 'ANDROID_FDSAN_OWNER_TYPE_FILE'? [/Users/builder/jenkins/workspace/xamarin-android-pr-builder-release/xamarin-android/src/sqlite-xamarin/sqlite-xamarin.csproj]

I got the same error when I rebased: #2590

[jonpryor]

The current build failed because the machine had NDK r18 installed (because that build machine previously built PR #2592), and thus the build machine is now "corrupt". :-(

We need to figure out support for NDK downgrades.

[jonathanpeppers]

build

[jonpryor]

It seems we shouldn't be using a full path here, but use WorkingDirectory instead?

The problem isn't the full path (and we want the full path, just for sanity).

The problem is that your git checkout is (partially) FUBAR.

Unfortunately I can't readily find how to fix a FUBAR repo, short of nuking it and checking it out again.

For example, a few weeks ago I moved my git checkout from one directory into another. git was not happy with this decision, because sometimes in git submodules the .git file contains a full path instead of a relative path, e.g.

$ cat external/mono/external/nuget-buildtasks/.git
gitdir: /Volumes/Xamarin-Work/xamarin-android/.git/modules/external/mono/modules/external/nuget-buildtasks

That's the new dir, not the old dir, but the problem is that it's a full path, so when I moved my git checkout, the path was invalidated, and every git operation which attempted to deal with that directory (and the 10 others that also had a full path) would fail, all of them saying that it wasn't a git repository.

I had to find and manually edit each of these in order to get git working again.

---

Regardless, using a full path should be perfectly valid, and if git fails on that, there's not much we can do.

What we can do is improve the error message. What we currently generate is not helpful, because the actual git error message is buried or not otherwise printed, which is why you had to manually run the command to see what the error was.

We should fix that: surface the fatal: not a git repository message so that the build log has something useful to go on.

[jonathanpeppers]

So I did a fresh checkout and I'm still having the problem with our private repo:

git clone https://github.com/xamarin/our-private-repo.git somedir
cd somedir
git submodule update --init --recursive
./configure --build-windows-cross=false
make reset-versions

This failure:

$ /usr/bin/git blame "/Users/myuser/Desktop/git/somedir/external/xamarin-android/Configuration.props"
fatal: '/Users/mysuser/Desktop/git/monodroid2/somedir/xamarin-android/Configuration.props' is outside repository

But this command works fine:

cd /Users/myuser/Desktop/git/somedir/external/xamarin-android/
/usr/bin/git blame "Configuration.props"

That's why I'm wondering if we can set WorkingDirectory to the full path, then use a related path within the repo's directory.

[jonpryor]

git requires that $CWD be within a git checkout, so this will fail:

$ cd $HOME
$ git blame /path/to/Configuration.props

(Unless $HOME is a git checkout, but how many people do that?)

When within a git repo, using a full path Works For Me™

$ cd /path/to/xamarin-android
$ git blame /path/to/xamarin-android/Configuration.props
# no error

Discussing this on gitter, it could be a git "bug"/"feature". It works for me with Apple git 2.17.2, while fails for @jonathanpeppers using Apple git 2.17.1.

Which suggests that we should accept this PR, to decrease git version dependencies.

[jonpryor]

build