Regression: Nerdbank.GitVersioning.GitException: The commit 0000000000000000000000000000000000000000 was not found in this repository.

[vchirikov]

Hello, I ran into a problem with the managed git implementation in nbgv (3.4.194).
The 3.3.37 version works fine.

> cat .git/HEAD
ref: refs/heads/my/build_system_setup

> dotnet nbgv get-version
 Unhandled exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Nerdbank.GitVersioning.GitException: The commit 0000000000000000000000000000000000000000 was not found in this repository.
     at Nerdbank.GitVersioning.ManagedGit.GitRepository.GetCommit(GitObjectId sha, Boolean readAuthor)
     at Nerdbank.GitVersioning.Managed.ManagedGitContext.TrySelectCommit(String committish)
     at Nerdbank.GitVersioning.Tool.Program.OnGetVersionCommand(String project, IReadOnlyList`1 metadata, String format, String variable, String commitIsh) in D:\a\1\s\src\nbgv\Program.cs:line 371
     --- End of inner exception stack trace ---
     at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
     at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
     at System.Delegate.DynamicInvokeImpl(Object[] args)
     at System.CommandLine.Invocation.ModelBindingCommandHandler.InvokeAsync(InvocationContext context)
     at System.CommandLine.Invocation.InvocationPipeline.<>c__DisplayClass4_0.<<BuildInvocationChain>b__0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c.<<UseParseErrorReporting>b__21_0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c__DisplayClass16_0.<<UseHelp>b__0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c__DisplayClass25_0.<<UseVersionOption>b__0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c__DisplayClass23_0.<<UseTypoCorrections>b__0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c.<<UseSuggestDirective>b__22_0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c.<<UseParseDirective>b__20_0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c.<<UseDebugDirective>b__11_0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c.<<RegisterWithDotnetSuggest>b__10_0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c__DisplayClass19_0.<<UseMiddleware>b__0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---
     at System.CommandLine.Builder.CommandLineBuilderExtensions.<>c__DisplayClass14_0.<<UseExceptionHandler>b__0>d.MoveNext()

The repo was cloned through git alternates and then repacked.

git repack -a -d && rm -rf .git/objects/info/alternates

[AArnott]

I think this may be fixed in the latest CI build. Can you confirm by trying out v3.4.203?

More instructions here: https://github.com/dotnet/Nerdbank.GitVersioning#how-do-i-consume-the-latest-changes-prior-to-their-release-on-nugetorg

[vchirikov]

I tried 3.4.203, nbgv call ended with the same result :(

[AArnott]

@qmfrederik What do you think? Can we fix this?

[epvanhouten]

I was trying to build a reproduction for this and am having trouble getting it to break.

I wrote the following script based on my, limited, understanding of git alternates.

$ErrorActionPreference = 'Stop'
$InformationPreference = 'Continue'

New-Item -ItemType Directory 602Test | Push-Location
dotnet new tool-manifest
dotnet tool install --version 3.4.194 nbgv

New-Item -ItemType Directory source | Push-Location
git init
dotnet nbgv install
git commit -a -m "Add nbgv to source repo"
$sourceRepo = (Get-Item .).FullName

Pop-Location
New-Item -ItemType Directory target | Push-Location
git clone --local --shared $sourceRepo .
Write-Information "Content of .git/info/objects/alternates pre-repack:"
Get-Content .git\objects\info\alternates
git repack -a -d

if(Test-Path .git\info\objects\alternates)
{
    Write-Information "Content of .git/info/alternates post-repack:"
    Get-Content .git\info\objects\alternates
    Get-ChildItem .git\objects\info\alternates | Remove-Item -Force
}else{
    Write-Information "Alternate configuration is gone"
}
dotnet nbgv get-version

Pop-Location
git --version
dotnet nbgv --version

Pop-Location

Which results in the following output:

The template "Dotnet local tool manifest file" was created successfully.
You can invoke the tool from this directory using the following commands: 'dotnet tool run nbgv' or 'dotnet nbgv'.
Tool 'nbgv' (version '3.4.194') was successfully installed. Entry is added to the manifest file C:\code\nbgv602\602Test\.config\dotnet-tools.json.
Initialized empty Git repository in C:/code/nbgv602/602Test/source/.git/
[master (root-commit) 293cb72] Add nbgv to source repo
 2 files changed, 22 insertions(+)
 create mode 100644 Directory.Build.props
 create mode 100644 version.json
Cloning into '.'...
done.
Content of .git/info/objects/alternates pre-repack:
C:\code\nbgv602\602Test\source/.git/objects
Enumerating objects: 4, done.
Counting objects: 100% (4/4), done.
Delta compression using up to 16 threads
Compressing objects: 100% (4/4), done.
Writing objects: 100% (4/4), done.
Total 4 (delta 0), reused 0 (delta 0), pack-reused 0
Alternate configuration is gone
Version:                      1.0.1.15401
AssemblyVersion:              1.0.0.0
AssemblyInformationalVersion: 1.0.1-beta+293cb728f2
NuGetPackageVersion:          1.0.1-beta
NpmPackageVersion:            1.0.1-beta
git version 2.30.1.windows.1
3.4.194+8126d95e2c

I feel like I am missing something in the setup.

Edit: Revised to something probably closer to being right... but still not getting a reproduction.

[qmfrederik]

I think this is caused by ResolveReference being unable to open the reference, after which it returns GitObjectId.Empty.

1. We should find out why ;-).
2. ResolveReference should probably throw instead.

@vchirikov What does cat .git/refs/heads/my/build_system_setup yield?

[qmfrederik]

@vchirikov If you're up to it, you should be able to fairly easily debug this yourself - something like this:

var repository = GitRepository.Create("path_to_your_repo");
var head = repository.GetHeadCommitSha();

// head is likely to be GitObjectId.Empty; we should find out why ;-)

should get you to the relevant part of the code.

[vchirikov]

It happened on a build server (TeamCity), I will try to reproduce it soon on my local repo.

[filipnavara]

Likely to be fixed by #613

[filipnavara]

git-packed-head.zip

Test repository. Created by git init, git commit --allow-empty -m "Empty commit", git pack-refs --all.

[vchirikov]

Sorry I was on vacation. I can confirm, the issue is resolved on 3.4.216