Add typehint in mmcv/utils* (#1998)

* Add typehint in mmcv/utils*

* Update mmcv/utils/registry.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

* Update mmcv/utils/registry.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

mmcv/utils/device_type.py

 # Copyright (c) OpenMMLab. All rights reserved.
 
 
-def is_ipu_available():
+def is_ipu_available() -> bool:
     try:
         import poptorch
         return poptorch.ipuHardwareIsAvailable()
@@ -12,7 +12,7 @@ def is_ipu_available():
 IS_IPU_AVAILABLE = is_ipu_available()
 
 
-def is_mlu_available():
+def is_mlu_available() -> bool:
     try:
         import torch
         return (hasattr(torch, 'is_mlu_available')

mmcv/utils/ext_loader.py

@@ -67,6 +67,6 @@ else:
         return ExtModule(*ext_list)
 
 
-def check_ops_exist():
+def check_ops_exist() -> bool:
     ext_loader = pkgutil.find_loader('mmcv._ext')
     return ext_loader is not None

mmcv/utils/registry.py

@@ -2,11 +2,14 @@
 import inspect
 import warnings
 from functools import partial
+from typing import Any, Dict, Optional
 
 from .misc import deprecated_api_warning, is_seq_of
 
 
-def build_from_cfg(cfg, registry, default_args=None):
+def build_from_cfg(cfg: Dict,
+                   registry: 'Registry',
+                   default_args: Optional[Dict] = None) -> Any:
     """Build a module from config dict when it is a class configuration, or
     call a function from config dict when it is a function configuration.