Fix bugs

src/dependency_injector/wiring.py

@@ -2,10 +2,18 @@
 
 import functools
 import inspect
+import sys
 import pkgutil
 from types import ModuleType
 from typing import Optional, Iterable, Callable, Any, Type, Dict, Generic, TypeVar
 
+# Spike for Python 3.6
+if sys.version_info < (3, 7):
+    from typing import GenericMeta
+else:
+    class GenericMeta(type):
+        ...
+
 from . import providers
 
 AnyContainer = Any
@@ -73,25 +81,12 @@ def _resolve_injections(fn: Callable[..., Any], container: AnyContainer) -> Dict
             continue
         marker = parameter.default
 
-        provider = None
-
         provider_name = container.resolve_provider_name(marker.provider)
         if provider_name:
             provider = container.providers[provider_name]
-
-        if config and isinstance(marker.provider, providers.ConfigurationOption):
-            full_option_name = marker.provider.get_name()
-            _, *parts = full_option_name.split('.')
-            relative_option_name = '.'.join(parts)
-            provider = config.get_option_provider(relative_option_name)
-            if parameter.annotation is int:
-                provider = provider.as_int()
-            elif parameter.annotation is float:
-                provider = provider.as_float()
-            elif parameter.annotation is not inspect.Parameter.empty:
-                provider = provider.as_(parameter.annotation)
-
-        if provider is None:
+        elif config and isinstance(marker.provider, providers.ConfigurationOption):
+            provider = _prepare_config_injection(marker.provider, parameter, config)
+        else:
             continue
 
         if isinstance(marker, Provide):
@@ -102,6 +97,24 @@ def _resolve_injections(fn: Callable[..., Any], container: AnyContainer) -> Dict
     return injections
 
 
+def _prepare_config_injection(
+        option: providers.ConfigurationOption,
+        parameter: inspect.Parameter,
+        config: providers.Configuration,
+) -> providers.Provider:
+    full_option_name = option.get_name()
+    _, *parts = full_option_name.split('.')
+    relative_option_name = '.'.join(parts)
+    provider = config.get_option_provider(relative_option_name)
+    if parameter.annotation is int:
+        provider = provider.as_int()
+    elif parameter.annotation is float:
+        provider = provider.as_float()
+    elif parameter.annotation is not inspect.Parameter.empty:
+        provider = provider.as_(parameter.annotation)
+    return provider
+
+
 def _resolve_container_config(container: AnyContainer) -> Optional[providers.Configuration]:
     for provider in container.providers.values():
         if isinstance(provider, providers.Configuration):
@@ -141,7 +154,11 @@ class ClassGetItemMeta(type):
         return cls(item)
 
 
-class _Marker(Generic[T], metaclass=ClassGetItemMeta):
+class GenericClassGetItemMeta(GenericMeta, ClassGetItemMeta):
+    pass
+
+
+class _Marker(Generic[T], metaclass=GenericClassGetItemMeta):
     def __init__(self, provider: providers.Provider) -> None:
         self.provider = provider