fix: refuse a profile_sync filter matching nothing

scripts/profile_sync.py

@@ -31,7 +31,7 @@ import yaml
 sys.path.insert(0, os.path.dirname(__file__))
 
 import upstream
-from common import load_emulator_profiles
+from common import load_emulator_profiles, suggest_names
 from upstream import CompareResult, find_renamed
 
 DEFAULT_CACHE = upstream.CACHE_DIR
@@ -3305,8 +3305,10 @@ def select_profiles(profiles: dict, args: argparse.Namespace) -> dict:
     """Profiles matching the selection flags."""
     if args.emulator:
         if args.emulator not in profiles:
-            print(f"unknown profile: {args.emulator}", file=sys.stderr)
-            raise SystemExit(1)
+            raise SystemExit(
+                f"ERROR: unknown profile {args.emulator}. "
+                + suggest_names([args.emulator], sorted(profiles), "verify.py --list-emulators")
+            )
         return {args.emulator: profiles[args.emulator]}
 
     selected = {}
@@ -3324,6 +3326,23 @@ def select_profiles(profiles: dict, args: argparse.Namespace) -> dict:
         selected[name] = profile
         if args.limit and len(selected) >= args.limit:
             break
+    if not selected:
+        # A misspelt filter selected nothing and the run said nothing: it
+        # read as "no profile of that system needs a re-read".
+        filters = ", ".join(
+            f"{flag} {value}" for flag, value in (
+                ("--system", args.system), ("--type", args.type_),
+                ("--stale-before", args.stale_before),
+            ) if value
+        )
+        hint = ""
+        if args.system:
+            systems = sorted({s for p in profiles.values() for s in p.get("systems") or []})
+            hint = " " + suggest_names([args.system], systems, "verify.py --list-systems")
+        elif args.type_:
+            kinds = sorted({str(p.get("type")) for p in profiles.values() if p.get("type")})
+            hint = f" Types: {', '.join(kinds)}."
+        raise SystemExit(f"ERROR: no profile matches {filters or 'the selection'}.{hint}")
     return selected
 
 

tests/test_profile_sync.py

@@ -4005,5 +4005,36 @@ class OfflineCacheMissIsNotGone(TestBuildReport):
             build_report("test", self._profile(["a.c:2"]), self.dir, offline=True)
 
 
+
+class TestSelectionNamesWhatMatchedNothing(unittest.TestCase):
+    """`--all --system atari-lynxx` printed nothing and exited 0, which read
+    as "no Lynx profile needs a re-read"; `--emulator handyy` offered no
+    suggestion."""
+
+    PROFILES = {
+        "handy": {"type": "libretro", "systems": ["atari-lynx"]},
+        "mednafen_lynx": {"type": "libretro", "systems": ["atari-lynx"]},
+    }
+
+    def _args(self, **values):
+        base = {"emulator": None, "system": None, "type_": None,
+                "stale_before": None, "limit": None}
+        return argparse.Namespace(**{**base, **values})
+
+    def test_a_misspelt_system_stops_and_suggests(self):
+        with self.assertRaises(SystemExit) as caught:
+            profile_sync.select_profiles(self.PROFILES, self._args(system="atari-lynxx"))
+        self.assertIn("atari-lynx", str(caught.exception.code))
+
+    def test_a_misspelt_emulator_suggests(self):
+        with self.assertRaises(SystemExit) as caught:
+            profile_sync.select_profiles(self.PROFILES, self._args(emulator="handyy"))
+        self.assertIn("Did you mean: handy", str(caught.exception.code))
+
+    def test_a_matching_filter_selects(self):
+        selected = profile_sync.select_profiles(self.PROFILES, self._args(system="atari-lynx"))
+        self.assertEqual(sorted(selected), ["handy", "mednafen_lynx"])
+
+
 if __name__ == "__main__":
     unittest.main()