def2stream: say what is missing when the AUTO_MEMORIES list is

Review asked for a missing RESULTS_DIR or blackboxes.txt to mean no
generated macros. It does not: do-auto-memories always writes the list,
empty when nothing was converted, so a missing one is a broken flow,
and passing over it would turn into "has no matching GDS/OAS cell"
errors for the generated macros further on. It stays a stop, now with
a message naming what is missing instead of a KeyError or
FileNotFoundError; under klayout -r the merge exits 1 with it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

Author: oharboe

flow/test/test_def2stream.py

@@ -373,12 +373,29 @@ def test_names_from_blackboxes_txt(self):
             )
 
     def test_missing_list_is_an_error(self):
+        # the flow always writes it; a missing list is a broken flow, not
+        # a design without generated macros
         with tempfile.TemporaryDirectory() as results:
-            with self.assertRaises(FileNotFoundError):
+            with self.assertRaisesRegex(RuntimeError, "blackboxes.txt is missing"):
                 def2stream.auto_memories_cells(
                     {"AUTO_MEMORIES": "1", "RESULTS_DIR": results}
                 )
 
+    def test_missing_results_dir_is_an_error(self):
+        with self.assertRaisesRegex(RuntimeError, "RESULTS_DIR is not set"):
+            def2stream.auto_memories_cells({"AUTO_MEMORIES": "1"})
+
+    def test_empty_list_allows_nothing(self):
+        with tempfile.TemporaryDirectory() as results:
+            os.mkdir(os.path.join(results, "memories"))
+            open(os.path.join(results, "memories", "blackboxes.txt"), "w").close()
+            self.assertEqual(
+                def2stream.auto_memories_cells(
+                    {"AUTO_MEMORIES": "1", "RESULTS_DIR": results}
+                ),
+                frozenset(),
+            )
+
 
 class TestOrphanCells(unittest.TestCase):
     def test_orphan_cell_is_error(self):

flow/util/def2stream.py

@@ -143,8 +143,18 @@ def auto_memories_cells(environ):
     """
     if environ.get("AUTO_MEMORIES") != "1":
         return frozenset()
-    path = os.path.join(environ["RESULTS_DIR"], "memories", "blackboxes.txt")
-    with open(path) as f:
+    # do-auto-memories always writes the list, empty when nothing was
+    # converted; without it the merge cannot tell a generated macro from
+    # a cell whose GDS is missing.
+    results_dir = environ.get("RESULTS_DIR")
+    if not results_dir:
+        raise RuntimeError("AUTO_MEMORIES=1 but RESULTS_DIR is not set")
+    path = os.path.join(results_dir, "memories", "blackboxes.txt")
+    if not os.path.isfile(path):
+        raise RuntimeError(
+            f"AUTO_MEMORIES=1 but {path} is missing; do-auto-memories writes it"
+        )
+    with open(path, encoding="utf-8") as f:
         return frozenset(line.split()[0] for line in f if line.strip())