Add stash with paths options

LibGit2Sharp.Tests/StashFixture.cs

@@ -237,6 +237,22 @@ public void CanStashAndApplyWithOptions()
             }
         }
 
+        [Fact]
+        public void CanStashWithFilePaths()
+        {
+            string path = SandboxStandardTestRepo();
+            using (var repo = new Repository(path))
+            {
+                var stasher = Constants.Signature;
+
+                const string filename = "modified_unstaged_file.txt";
+
+                var stash = repo.Stashes.Add(stasher, "This stash one file", StashModifiers.Default, new[] { filename });
+
+                Assert.NotNull(stash);
+            }
+        }
+
         [Fact]
         public void CanStashAndPop()
         {

LibGit2Sharp/Core/GitStashSaveOpts.cs

@@ -0,0 +1,28 @@
+using System.Runtime.InteropServices;
+
+namespace LibGit2Sharp.Core
+{
+    [StructLayout(LayoutKind.Sequential)]
+    internal unsafe struct GitStashSaveOpts
+    {
+        public GitStashSaveOpts(
+            StashModifiers flags,
+            git_signature* stasher,
+            string message,
+            GitStrArray paths
+        )
+        {
+            Version = 1;
+            Flags = flags;
+            Stasher = stasher;
+            Message = message;
+            Paths = paths;
+        }
+
+        public uint Version;
+        public StashModifiers Flags;
+        public git_signature* Stasher;
+        public string Message;
+        public GitStrArray Paths;
+    }
+}

LibGit2Sharp/Core/NativeMethods.cs

@@ -1744,6 +1744,12 @@ internal static extern unsafe int git_stash_save(
             [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string message,
             StashModifiers flags);
 
+        [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]
+        internal static extern unsafe int git_stash_save_with_opts(
+            out GitOid stashOid,
+            git_repository* repo,
+            ref GitStashSaveOpts saveOpts);
+
         [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
         internal delegate int git_stash_cb(
             UIntPtr index,

LibGit2Sharp/Core/Proxy.cs

@@ -2857,6 +2857,35 @@ public static unsafe ObjectId git_stash_save(
             }
         }
 
+        public static unsafe ObjectId git_stash_save_with_opts(
+            RepositoryHandle repo,
+            Signature stasher,
+            string message,
+            StashModifiers options,
+            string[] paths)
+        {
+            using var sigHandle = stasher.BuildHandle();
+            using var pathStrArray = GitStrArrayManaged.BuildFrom(paths ?? []);
+
+            var stashOpts = new GitStashSaveOpts(
+                options,
+                sigHandle,
+                message,
+                pathStrArray.Array
+            );
+
+            int res = NativeMethods.git_stash_save_with_opts(out var stashOid, repo, ref stashOpts);
+
+            if (res == (int)GitErrorCode.NotFound)
+            {
+                return null;
+            }
+
+            Ensure.Int32Result(res);
+
+            return new ObjectId(stashOid);
+        }
+
         public static unsafe ICollection<TResult> git_stash_foreach<TResult>(
             RepositoryHandle repo,
             Func<int, IntPtr, GitOid, TResult> resultSelector)

LibGit2Sharp/StashCollection.cs

@@ -113,6 +113,18 @@ public virtual Stash Add(Signature stasher, string message)
             return Add(stasher, message, StashModifiers.Default);
         }
 
+        public virtual Stash Add(Signature stasher, string message, StashModifiers options, string[] paths)
+        {
+            ObjectId oid = Proxy.git_stash_save_with_opts(repo.Handle, stasher, message, options, paths);
+
+            if (oid == null)
+            {
+                return null;
+            }
+
+            return new Stash(repo, oid, 0);
+        }
+
         /// <summary>
         /// Creates a stash with the specified message.
         /// </summary>

LibGit2Sharp/StashModifiers.cs

@@ -30,5 +30,10 @@ public enum StashModifiers
         /// cleaned up from the working directory
         /// </summary>
         IncludeIgnored = (1 << 2),
+
+        /// <summary>
+        /// All changes in the index and working directory are left intact
+        /// </summary>
+        KeepAll = (1 << 3),
     }
 }