Add warning on extra @inject

Author: ZipFile

pyproject.toml

@@ -108,6 +108,7 @@ markers = [
     "pydantic: Tests with Pydantic as a dependency",
 ]
 filterwarnings = [
+    "ignore::dependency_injector.wiring.DIWiringWarning",
     "ignore:Module \"dependency_injector.ext.aiohttp\" is deprecated since version 4\\.0\\.0:DeprecationWarning",
     "ignore:Module \"dependency_injector.ext.flask\" is deprecated since version 4\\.0\\.0:DeprecationWarning",
     "ignore:Please use \\`.*?\\` from the \\`scipy.*?\\`(.*?)namespace is deprecated\\.:DeprecationWarning",

src/dependency_injector/wiring.py

@@ -24,6 +24,7 @@
     Union,
     cast,
 )
+from warnings import warn
 
 try:
     from typing import Self
@@ -130,6 +131,10 @@ def extract_marker_from_fast_depends(param: Any) -> Any:
     Container = Any
 
 
+class DIWiringWarning(RuntimeWarning):
+    """Base class for all warnings raised by the wiring module."""
+
+
 class PatchedRegistry:
 
     def __init__(self) -> None:
@@ -520,6 +525,15 @@ def unwire(  # noqa: C901
 def inject(fn: F) -> F:
     """Decorate callable with injecting decorator."""
     reference_injections, reference_closing = _fetch_reference_injections(fn)
+
+    if not reference_injections:
+        warn(
+            "@inject decorator is not required for this function",
+            DIWiringWarning,
+            stacklevel=2,
+        )
+        return fn
+
     patched = _get_patched(fn, reference_injections, reference_closing)
     return cast(F, patched)