Add suffix checks (#4711)

* Add suffix checks

* Cleanup

* Cleanup2

* Cleanup3

detect.py

@@ -21,8 +21,9 @@ sys.path.append(FILE.parents[0].as_posix())  # add yolov5/ to path
 
 from models.experimental import attempt_load
 from utils.datasets import LoadStreams, LoadImages
-from utils.general import check_img_size, check_requirements, check_imshow, colorstr, is_ascii, non_max_suppression, \
-    apply_classifier, scale_coords, xyxy2xywh, strip_optimizer, set_logging, increment_path, save_one_box
+from utils.general import check_img_size, check_imshow, check_requirements, check_suffix, colorstr, is_ascii, \
+    non_max_suppression, apply_classifier, scale_coords, xyxy2xywh, strip_optimizer, set_logging, increment_path, \
+    save_one_box
 from utils.plots import Annotator, colors
 from utils.torch_utils import select_device, load_classifier, time_sync
 
@@ -68,8 +69,9 @@ def run(weights='yolov5s.pt',  # model.pt path(s)
 
     # Load model
     w = weights[0] if isinstance(weights, list) else weights
-    classify, suffix = False, Path(w).suffix.lower()
-    pt, onnx, tflite, pb, saved_model = (suffix == x for x in ['.pt', '.onnx', '.tflite', '.pb', ''])  # backend
+    classify, suffix, suffixes = False, Path(w).suffix.lower(), ['.pt', '.onnx', '.tflite', '.pb', '']
+    check_suffix(w, suffixes)  # check weights have acceptable suffix
+    pt, onnx, tflite, pb, saved_model = (suffix == x for x in suffixes)  # backend booleans
     stride, names = 64, [f'class{i}' for i in range(1000)]  # assign defaults
     if pt:
         model = attempt_load(weights, map_location=device)  # load FP32 model