Merge pull request #1484 from patricsss/patricsss/fix-1455

utils: fix diff so subpaths work for sparse checkouts, fixes 1455

utils/merkletrie/change.go

···
 			}
 			return err
 		}
-		if current.IsDir() {
+		if current.IsDir() || current.Skip() {
 			continue
 		}
 		l.Add(ctor(current))

utils/merkletrie/index/node.go

···
 			parent := fullpath
 			fullpath = path.Join(fullpath, part)
 
-			if _, ok := m[fullpath]; ok {
+			// It's possible that the first occurrence of subdirectory is skipped.
+			// The parent node can be created with SkipWorktree set to true, but
+			// if any future children do not skip their subtree, the entire lineage
+			// of the tree needs to have this value set to false so that subdirectories
+			// are not ignored.
+			if parentNode, ok := m[fullpath]; ok {
+				if e.SkipWorktree == false {
+					parentNode.skip = false
+				}
 				continue
 			}
 

utils/merkletrie/index/node_test.go

···
 
 import (
 	"bytes"
-	"path/filepath"
+	"path"
 	"testing"
 
 	"github.com/go-git/go-git/v5/plumbing"
···
 func (s *NoderSuite) TestDiffChange() {
 	indexA := &index.Index{
 		Entries: []*index.Entry{{
-			Name: filepath.Join("bar", "baz", "bar"),
+			Name: path.Join("bar", "baz", "bar"),
 			Hash: plumbing.NewHash("8ab686eafeb1f44702738c8b0f24f2567c36da6d"),
 		}},
 	}
 
 	indexB := &index.Index{
 		Entries: []*index.Entry{{
-			Name: filepath.Join("bar", "baz", "foo"),
+			Name: path.Join("bar", "baz", "foo"),
 			Hash: plumbing.NewHash("8ab686eafeb1f44702738c8b0f24f2567c36da6d"),
 		}},
 	}
···
 	s.Len(ch, 2)
 }
 
+func (s *NoderSuite) TestDiffSkipIssue1455() {
+	indexA := &index.Index{
+		Entries: []*index.Entry{
+			{
+				Name:         path.Join("bar", "baz", "bar"),
+				Hash:         plumbing.NewHash("8ab686eafeb1f44702738c8b0f24f2567c36da6d"),
+				SkipWorktree: true,
+			},
+			{
+				Name:         path.Join("bar", "biz", "bat"),
+				Hash:         plumbing.NewHash("8ab686eafeb1f44702738c8b0f24f2567c36da6d"),
+				SkipWorktree: false,
+			},
+		},
+	}
+
+	indexB := &index.Index{}
+
+	ch, err := merkletrie.DiffTree(NewRootNode(indexB), NewRootNode(indexA), isEquals)
+	s.NoError(err)
+	s.Len(ch, 1)
+	a, err := ch[0].Action()
+	s.NoError(err)
+	s.Equal(a, merkletrie.Insert)
+}
+
 func (s *NoderSuite) TestDiffDir() {
 	indexA := &index.Index{
 		Entries: []*index.Entry{{
···
 
 	indexB := &index.Index{
 		Entries: []*index.Entry{{
-			Name: filepath.Join("foo", "bar"),
+			Name: path.Join("foo", "bar"),
 			Hash: plumbing.NewHash("8ab686eafeb1f44702738c8b0f24f2567c36da6d"),
 		}},
 	}