feat: follow a ref when its subject moved with it

scripts/profile_sync.py

@@ -33,10 +33,11 @@ ANON_QUOTA = 60
 TRIAGE_PATH_SAMPLE = 5
 
 STATUS_ORDER = (
-    "ANCHORED", "EXTERNAL", "SHIFTED", "RENAMED", "AMBIGUOUS", "CHANGED", "GONE",
+    "ANCHORED", "EXTERNAL", "SHIFTED", "RENAMED", "MOVED", "AMBIGUOUS",
+    "CHANGED", "GONE",
 )
 REVIEW_STATUSES = ("CHANGED", "GONE", "AMBIGUOUS")
-REBASE_STATUSES = ("SHIFTED", "RENAMED")
+REBASE_STATUSES = ("SHIFTED", "RENAMED", "MOVED")
 
 WIDEN_STEPS = (0, 3, 6, 12, 25, 50)
 MAX_MATCH_LINES = 20000
@@ -462,6 +463,16 @@ def anchor_part(
                 anchored = retry
                 note = f"cited line was {nudged[0] - part.start:+d} off its subject"
     status = anchored.status
+    if status == "CHANGED" and anchored.start is not None and tokens:
+        # The cited code changed, but the value the entry declares is provably
+        # inside the new range, so the ref can follow it without a judgement
+        # call on the edit itself.
+        block = "\n".join(
+            head_lines[anchored.start - 1 : (anchored.end or anchored.start)]
+        ).lower()
+        if any(token in block for token in tokens):
+            status = "MOVED"
+            note = "content edited, declared value present in the new range"
     if renamed and status in ("ANCHORED", "SHIFTED"):
         status = "RENAMED"
     return PartResult(

tests/test_profile_sync.py

@@ -641,6 +641,48 @@ class TestAnchorPart(unittest.TestCase):
         self.assertIn("no rename found", result.reason)
 
 
+class TestMovedStatus(unittest.TestCase):
+    """A changed range whose subject is provably inside it can be followed."""
+
+    def test_declared_value_inside_the_new_range_gives_moved(self):
+        fetch = make_fetch({
+            (PIN, "a.c"): ["x", 'load("bios.bin", 0x1000)'],
+            (HEAD, "a.c"): ["pad", "pad", 'load("bios.bin", 0x2000, flags)'],
+        })
+        result = anchor_part(
+            RefPart("a.c", 2, 2, "a.c:2"),
+            fetch,
+            renamer(CompareResult([], False)),
+            None,
+            ["bios.bin"],
+        )
+        self.assertEqual(result.status, "MOVED")
+        self.assertEqual(result.start, 3)
+        self.assertIn("declared value present", result.reason)
+
+    def test_value_absent_from_the_new_range_stays_changed(self):
+        fetch = make_fetch({
+            (PIN, "a.c"): ["x", 'load("bios.bin")'],
+            (HEAD, "a.c"): ["x", 'load("other.bin")'],
+        })
+        result = anchor_part(
+            RefPart("a.c", 2, 2, "a.c:2"),
+            fetch,
+            renamer(CompareResult([], False)),
+            None,
+            ["bios.bin"],
+        )
+        self.assertEqual(result.status, "CHANGED")
+
+    def test_moved_is_mechanically_recalable(self):
+        self.assertIn("MOVED", profile_sync.REBASE_STATUSES)
+        self.assertNotIn("MOVED", profile_sync.REVIEW_STATUSES)
+
+    def test_moved_ranks_below_ambiguous(self):
+        self.assertEqual(worst_status(["MOVED", "AMBIGUOUS"]), "AMBIGUOUS")
+        self.assertEqual(worst_status(["MOVED", "SHIFTED"]), "MOVED")
+
+
 class TestSelectRepo(unittest.TestCase):
     def test_source_wins_over_upstream(self):
         repo = select_repo(