[pythonic config] Add warning message when config arg is not named 'c…

…onfig' (#16563)

## Summary

Raises a warning message if an op/asset function has a parameter
annotated with `dagster.Config` subclass that is not called `config`:

```python
>>> @op
... def my_op(not_called_config: MyConfig):
...    pass
...
ConfigArgumentWarning: Parameter 'not_called_config' on op/asset function 'my_op' was annotated as a dagster.Config type. Did you mean to name this parameter 'config' instead?

To mute this warning, invoke warnings.filterwarnings("ignore", category=dagster.ConfigArgumentWarning) or use one of the other methods described at https://docs.python.org/3/library/warnings.html#describing-warning-filters.
  warnings.warn(
```

Meant to address/improve situations like
dagster-io/internal#6683 (comment)

The user may quiet this warning by muting the new
`dagster.ConfigArgumentWarning` warning type.

## Test Plan

New unit test.

python_modules/dagster/dagster/__init__.py

@@ -583,7 +583,10 @@
 )
 from dagster._utils.dagster_type import check_dagster_type as check_dagster_type
 from dagster._utils.log import get_dagster_logger as get_dagster_logger
-from dagster._utils.warnings import ExperimentalWarning as ExperimentalWarning
+from dagster._utils.warnings import (
+    ConfigArgumentWarning as ConfigArgumentWarning,
+    ExperimentalWarning as ExperimentalWarning,
+)
 from dagster.version import __version__ as __version__
 
 # ruff: isort: split

python_modules/dagster/dagster/_core/definitions/decorators/op_decorator.py

@@ -31,7 +31,7 @@
 )
 from dagster._core.errors import DagsterInvalidDefinitionError
 from dagster._core.types.dagster_type import DagsterTypeKind
-from dagster._utils.warnings import normalize_renamed_param
+from dagster._utils.warnings import config_argument_warning, normalize_renamed_param
 
 from ..input import In, InputDefinition
 from ..output import Out
@@ -91,6 +91,8 @@ def __call__(self, fn: Callable[..., Any]) -> "OpDefinition":
             else NoContextDecoratedOpFunction(decorated_fn=fn)
         )
 
+        compute_fn.validate_malformed_config()
+
         if compute_fn.has_config_arg():
             check.param_invariant(
                 self.config_schema is None or self.config_schema == {},
@@ -302,6 +304,15 @@ def has_config_arg(self) -> bool:
 
         return False
 
+    def validate_malformed_config(self) -> None:
+        from dagster._config.pythonic_config.config import Config
+        from dagster._config.pythonic_config.type_check_utils import safe_is_subclass
+
+        positional_inputs = self.positional_inputs()
+        for param in get_function_params(self.decorated_fn):
+            if safe_is_subclass(param.annotation, Config) and param.name in positional_inputs:
+                config_argument_warning(param.name, self.name)
+
     def get_config_arg(self) -> Parameter:
         for param in get_function_params(self.decorated_fn):
             if param.name == "config":

python_modules/dagster/dagster/_utils/warnings.py

@@ -95,6 +95,32 @@ def experimental_warning(
     )
 
 
+# ########################
+# ##### Config arg warning
+# ########################
+
+CONFIG_WARNING_HELP = (
+    "To mute this warning, invoke"
+    ' warnings.filterwarnings("ignore", category=dagster.ConfigArgumentWarning) or use'
+    " one of the other methods described at"
+    " https://docs.python.org/3/library/warnings.html#describing-warning-filters."
+)
+
+
+class ConfigArgumentWarning(SyntaxWarning):
+    pass
+
+
+def config_argument_warning(param_name: str, function_name: str) -> None:
+    warnings.warn(
+        f"Parameter '{param_name}' on op/asset function '{function_name}' was annotated as"
+        " a dagster.Config type. Did you mean to name this parameter 'config'"
+        " instead?\n\n"
+        f"{CONFIG_WARNING_HELP}",
+        ConfigArgumentWarning,
+    )
+
+
 # ########################
 # ##### DISABLE DAGSTER WARNINGS
 # ########################

python_modules/dagster/dagster_tests/core_tests/pythonic_config_tests/test_errors.py

@@ -1,3 +1,4 @@
+import warnings
 from typing import Tuple
 
 import pytest
@@ -452,3 +453,39 @@ def test_custom_dagster_type_as_config_type() -> None:
 
         class MyOpConfig(Config):
             dagster_type_field: DagsterDatetime = datetime(year=2023, month=4, day=30)  # type: ignore
+
+
+def test_config_named_wrong_thing() -> None:
+    with warnings.catch_warnings(record=True) as w:
+        warnings.simplefilter("always")
+
+        class DoSomethingConfig(Config):
+            a_str: str
+
+        assert len(w) == 0
+
+        @op
+        def my_op(config_named_wrong: DoSomethingConfig):
+            pass
+
+        assert len(w) == 1
+        assert (
+            w[0]
+            .message.args[0]  # type: ignore
+            .startswith(
+                "Parameter 'config_named_wrong' on op/asset function 'my_op' was annotated as a dagster.Config type. Did you mean to name this parameter 'config' instead?"
+            )
+        )
+
+        @asset
+        def my_asset(config_named_wrong: DoSomethingConfig):
+            pass
+
+        assert len(w) == 2
+        assert (
+            w[1]
+            .message.args[0]  # type: ignore
+            .startswith(
+                "Parameter 'config_named_wrong' on op/asset function 'my_asset' was annotated as a dagster.Config type. Did you mean to name this parameter 'config' instead?"
+            )
+        )