Fix HEAD for worktrees

src/GitVersionCore.Tests/GitVersionExecutorTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using System.Linq;
 using System.Text;
 using GitTools.Testing;
 using GitVersion;
@@ -507,6 +508,33 @@ public void GetDotGitDirectoryWorktree()
             });
         }
 
+        [Test]
+        [Category("NoMono")]
+        [Description("LibGit2Sharp fails when running under Mono")]
+        public void CalculateVersionFromWorktreeHead()
+        {
+            using var fixture = new EmptyRepositoryFixture();
+            var repoDir = new DirectoryInfo(fixture.RepositoryPath);
+            var worktreePath = Path.Combine(repoDir.Parent.FullName, $"{repoDir.Name}-v1");
+
+            fixture.Repository.MakeATaggedCommit("v1.0.0");
+            var branchV1 = fixture.Repository.CreateBranch("support/1.0");
+
+            fixture.Repository.MakeATaggedCommit("v2.0.0");
+
+            fixture.Repository.Worktrees.Add(branchV1.CanonicalName, "1.0", worktreePath, false);
+            using var worktreeFixture = new LocalRepositoryFixture(new Repository(worktreePath));
+
+            var arguments = new Arguments { TargetPath = worktreePath };
+
+            var calculator = GetGitVersionCalculator(arguments);
+            var version = calculator.CalculateVersionVariables();
+
+            version.SemVer.ShouldBe("1.0.0");
+            var commits = worktreeFixture.Repository.Head.Commits;
+            version.Sha.ShouldBe(commits.First().Sha);
+        }
+
         private void RepositoryScope(Action<EmptyRepositoryFixture, VersionVariables> fixtureAction = null)
         {
             // Make sure GitVersion doesn't trigger build server mode when we are running the tests

src/GitVersionCore.Tests/IntegrationTests/WorktreeScenarios.cs

@@ -0,0 +1,32 @@
+using GitTools.Testing;
+using LibGit2Sharp;
+using NUnit.Framework;
+using System.IO;
+
+namespace GitVersionCore.Tests.IntegrationTests
+{
+
+    [TestFixture]
+    public class WorktreeScenarios : TestBase
+    {
+
+        [Test]
+        public void UseWorktreeRepositoryForVersion()
+        {
+            using var fixture = new EmptyRepositoryFixture();
+            var repoDir = new DirectoryInfo(fixture.RepositoryPath);
+            var worktreePath = Path.Combine(repoDir.Parent.FullName, $"{repoDir.Name}-v1");
+
+            fixture.Repository.MakeATaggedCommit("v1.0.0");
+            var branchV1 = fixture.Repository.CreateBranch("support/1.0");
+
+            fixture.Repository.MakeATaggedCommit("v2.0.0");
+            fixture.AssertFullSemver("2.0.0");
+
+            fixture.Repository.Worktrees.Add(branchV1.CanonicalName, "1.0", worktreePath, false);
+            using var worktreeFixture = new LocalRepositoryFixture(new Repository(worktreePath));
+            worktreeFixture.AssertFullSemver("1.0.0");
+        }
+
+    }
+}

src/GitVersionCore/GitPreparer.cs

@@ -26,7 +26,7 @@ public class GitPreparer : IGitPreparer
 
         public string GetProjectRootDirectory() => projectRootDirectory ??= GetProjectRootDirectoryInternal();
 
-        private bool IsDynamicGitRepository => !string.IsNullOrWhiteSpace(DynamicGitRepositoryPath);
+        public bool IsDynamicGitRepository => !string.IsNullOrWhiteSpace(DynamicGitRepositoryPath);
         private string DynamicGitRepositoryPath;
 
         public GitPreparer(ILog log, IEnvironment environment, IOptions<Arguments> options)

src/GitVersionCore/GitVersionCalculator.cs

@@ -106,7 +106,11 @@ private VersionVariables ExecuteInternal(string targetBranch, string commitId, C
         {
             var configuration = configProvider.Provide(overrideConfig: overrideConfig);
 
-            return gitPreparer.GetDotGitDirectory().WithRepository(repo =>
+            var path = gitPreparer.IsDynamicGitRepository
+                ? gitPreparer.GetDotGitDirectory()
+                : gitPreparer.GetProjectRootDirectory();
+
+            return path.WithRepository(repo =>
             {
                 var gitVersionContext = new GitVersionContext(repo, log, targetBranch, configuration, commitId: commitId);
                 var semanticVersion = gitVersionFinder.FindVersion(gitVersionContext);

src/GitVersionCore/GitVersionContext.cs

@@ -175,10 +175,12 @@ private static Branch GetTargetBranch(IRepository repository, string targetBranc
                 {
                     // In the case where HEAD is not the desired branch, try to find the branch with matching name
                     desiredBranch = repository?.Branches?
-                        .SingleOrDefault(b =>
+                        .Where(b =>
                             b.CanonicalName == targetBranch ||
                             b.FriendlyName == targetBranch ||
-                            b.NameWithoutRemote() == targetBranch);
+                            b.NameWithoutRemote() == targetBranch)
+                        .OrderBy(b => b.IsRemote)
+                        .FirstOrDefault();
 
                     // Failsafe in case the specified branch is invalid
                     desiredBranch ??= repository.Head;

src/GitVersionCore/IGitPreparer.cs

@@ -7,5 +7,6 @@ public interface IGitPreparer
         string GetDotGitDirectory();
         string GetTargetUrl();
         string GetWorkingDirectory();
+        bool IsDynamicGitRepository { get; }
     }
 }