Remove dead files.dat references from build config (closes #22)

files.dat was the pre-database on-disk scan format; nothing has
produced it since the persistent SQLite database landed. Drop the
stale references from Makefile clean, .gitignore and .dockerignore.
make clean still removes the binary, and .gitignore still covers the
actual database artifacts (*.sqlite, *.sqlite-shm, *.sqlite-wal). The
sole remaining files.dat mention is the historical entry in TODO.md.

Model: opus-4-8

.dockerignore

@@ -2,7 +2,6 @@
 .claude
 .DS_Store
 sfdupes
-files.dat
 *.log
 *.out
 *.test

.gitignore

@@ -27,7 +27,6 @@ node_modules/
 *.log
 
 # Local scan data
-files.dat
 *.sqlite
 *.sqlite-shm
 *.sqlite-wal

Makefile

@@ -46,4 +46,4 @@ hooks:
 	@script/install-precommit
 
 clean:
-	rm -f $(BINARY) files.dat
+	rm -f $(BINARY)

TODO.md

@@ -29,11 +29,9 @@
 
 # Completed Steps
 
-- test the `-x` filesystem-boundary rejection branch by calling
+- remove the dead `files.dat` references from `Makefile`, `.gitignore`
-  `subdirJob` directly: reject across a boundary, bypass when the root
+  and `.dockerignore` (2026-09-21, branch `next`, closes
-  device is unknown, stat-error warning, and default crossing
+  https://git.eeqj.de/sneak/sfdupes/issues/22)
-  (2026-09-21, branch `next`, closes
-  https://git.eeqj.de/sneak/sfdupes/issues/17)
 
 - fix the lint-image pin comments and `FROM` form in `Dockerfile` and
   `Dockerfile.lint` (2026-08-10, branch `next`, closes

scan_test.go

@@ -6,9 +6,7 @@ import (
 	"crypto/sha256"
 	"database/sql"
 	"encoding/hex"
-	"errors"
 	"fmt"
-	"io/fs"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -326,152 +324,6 @@ func TestDeviceOfInfo(t *testing.T) {
 	}
 }
 
-// dirEntryFor returns the fs.DirEntry for name within dir, obtained via
-// the same os.ReadDir the walk uses, so it carries a real Info().
-func dirEntryFor(t *testing.T, dir, name string) fs.DirEntry {
-	t.Helper()
-
-	entries, err := os.ReadDir(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	for _, e := range entries {
-		if e.Name() == name {
-			return e
-		}
-	}
-
-	t.Fatalf("entry %q not found in %q", name, dir)
-
-	return nil
-}
-
-// callSubdirJob runs subdirJob against e under parent, collecting any
-// warning events it emits (subdirJob emits at most one).
-func callSubdirJob(t *testing.T, p string, e fs.DirEntry,
-	parent dirJob, oneFS bool,
-) (dirJob, bool, []walkEvent) {
-	t.Helper()
-
-	events := make(chan walkEvent, 1)
-	job, ok := subdirJob(t.Context(), p, e, parent, oneFS, events)
-	close(events)
-
-	var evs []walkEvent
-	for ev := range events {
-		evs = append(evs, ev)
-	}
-
-	return job, ok, evs
-}
-
-// TestSubdirJobOneFilesystem exercises the -x boundary check in
-// subdirJob directly, so no second real filesystem is needed. The
-// subdirectory's real device is compared against a fabricated operand
-// device.
-func TestSubdirJobOneFilesystem(t *testing.T) {
-	t.Parallel()
-
-	dir := t.TempDir()
-
-	sub := filepath.Join(dir, "sub")
-
-	err := os.Mkdir(sub, 0o750)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	info, err := os.Lstat(sub)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	dev, ok := deviceOfInfo(info)
-	if !ok {
-		t.Skip("platform exposes no device id")
-	}
-
-	// A device the subdirectory is not on, standing in for an operand
-	// rooted on a different filesystem.
-	otherDev := dev + 1
-	e := dirEntryFor(t, dir, "sub")
-
-	cases := []struct {
-		name   string
-		oneFS  bool
-		parent dirJob
-		wantOK bool
-	}{
-		// -x on, subdirectory on a different device than its operand:
-		// descent is refused.
-		{"reject across boundary", true,
-			dirJob{rootDev: otherDev, rootDevOK: true}, false},
-		// -x on but the operand's own device is unknown: the boundary
-		// check is bypassed and descent proceeds.
-		{"bypass when root device unknown", true,
-			dirJob{rootDev: otherDev, rootDevOK: false}, true},
-		// Default (no -x): boundaries are crossed even onto a different
-		// device.
-		{"cross by default", false,
-			dirJob{rootDev: otherDev, rootDevOK: true}, true},
-	}
-
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			job, ok, evs := callSubdirJob(t, sub, e, tc.parent, tc.oneFS)
-			if ok != tc.wantOK {
-				t.Fatalf("accepted = %v, want %v", ok, tc.wantOK)
-			}
-
-			if len(evs) != 0 {
-				t.Fatalf("unexpected events: %+v", evs)
-			}
-
-			if ok && job.path != sub {
-				t.Fatalf("job.path = %q, want %q", job.path, sub)
-			}
-		})
-	}
-}
-
-// errInfoUnavailable is returned by errDirEntry.Info().
-var errInfoUnavailable = errors.New("info unavailable")
-
-// errDirEntry is a directory entry whose Info() always fails, driving
-// subdirJob's stat-error branch deterministically.
-type errDirEntry struct{ name string }
-
-func (e errDirEntry) Name() string { return e.name }
-func (errDirEntry) IsDir() bool    { return true }
-func (errDirEntry) Type() fs.FileMode {
-	return fs.ModeDir
-}
-
-func (errDirEntry) Info() (fs.FileInfo, error) {
-	return nil, errInfoUnavailable
-}
-
-// TestSubdirJobStatError asserts that when a subdirectory's Info()
-// fails under -x, subdirJob warns and refuses descent.
-func TestSubdirJobStatError(t *testing.T) {
-	t.Parallel()
-
-	p := "/does/not/matter/sub"
-
-	_, ok, evs := callSubdirJob(t, p, errDirEntry{name: "sub"},
-		dirJob{rootDev: 1, rootDevOK: true}, true)
-	if ok {
-		t.Fatal("descent accepted after stat error, want refused")
-	}
-
-	if len(evs) != 1 || !evs[0].fail || !strings.Contains(evs[0].warn, p) {
-		t.Fatalf("want one warning naming the path, got %+v", evs)
-	}
-}
-
 // buildSmokeTree recreates the README smoke-test filesystem layout
 // with deterministic content and returns the tree root.
 func buildSmokeTree(t *testing.T) string {