libgit2 / libgit2/libgit2sharp

LibGit2Sharp.Core.Proxy.git_commit_tree_id throws NullReferenceException in shallow clones

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Dominant language
C#
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Description

Reproduction steps
dotnet tool install -g nbgv
git clone https://github.com/aarnott/nerdbank.streams  --depth 10
cd .\nerdbank.streams\
nbgv get-version
Expected behavior

An exception thrown explaining that data is missing because of a shallow clone.

Actual behavior

A NullReferenceException that does not suggest the underlying problem.

Unhandled Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at LibGit2Sharp.Core.Proxy.git_commit_tree_id(ObjectHandle obj)
   at LibGit2Sharp.Commit.<>c__DisplayClass11_0.<.ctor>b__0(ObjectHandle obj)
   at LibGit2Sharp.Core.GitObjectLazyGroup.<>c__DisplayClass3_0`1.<Singleton>b__0()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at Nerdbank.GitVersioning.VersionFile.GetVersion(Commit commit, String repoRelativeProjectDirectory) in D:\a\1\s\src\NerdBank.GitVersioning\VersionFile.cs:line 52
   at Nerdbank.GitVersioning.GitExtensions.CommitMatchesVersion(Commit commit, SemanticVersion expectedVersion, Position comparisonPrecision, String repoRelativeProjectDirectory) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 450
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 676
   at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping)   at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
 in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at System.Linq.Enumerable.Max[TSource](IEnumerable`1 source, Func`2 selector)
 in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at Nerdbank.GitVersioning.GitExtensions.GetCommitHeight(Commit commit, Dictionary`2 heights, Func`2 continueStepping) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 681
   at Nerdbank.GitVersioning.GitExtensions.GetVersionHeight(Commit commit, String repoRelativeProjectDirectory, Version baseVersion) in D:\a\1\s\src\NerdBank.GitVersioning\GitExtensions.cs:line 65
   at Nerdbank.GitVersioning.VersionOracle..ctor(String projectDirectory, Repository repo, Commit head, ICloudBuild cloudBuild, Nullable`1 overrideVersionHeightOffset, String projectPathRelativeToGitRepoRoot) in D:\a\1\s\src\NerdBank.GitVersioning\VersionOracle.cs:line 86
   at Nerdbank.GitVersioning.Tool.Program.OnGetVersionCommand(String projectPath, String format, String singleVariable, String versionOrRef) in D:\a\1\s\src\nbgv\Program.cs:line 305
   at Nerdbank.GitVersioning.Tool.Program.MainInner(String[] args) in D:\a\1\s\src\nbgv\Program.cs:line 149
   --- End of inner exception stack trace ---
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Version of LibGit2Sharp (release number or SHA1)

0.27.0-preview.7+gd47cfd9144.libgit2-572e4d8

Operating system(s) tested; .NET runtime tested

Windows 10. .NET Core

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at LibGit2Sharp.Core.Proxy.git_commit_tree_id and reproduce the supplied nbgv command sequence with a --depth 10 clone. Done means missing data from a shallow clone produces an explanatory exception instead of a NullReferenceException; the payload names no regression test or source file beyond this entry point.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp, git
Domain
devtools
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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