Fix error message for staticmethod/classmethod order with validate_ca…

…ll (#6686)

Co-authored-by: Samuel Colvin <s@muelcolvin.com>

pydantic/validate_call.py

@@ -47,6 +47,9 @@ def validate_call(
     """
 
     def validate(function: AnyCallableT) -> AnyCallableT:
+        if isinstance(function, (classmethod, staticmethod)):
+            name = type(function).__name__
+            raise TypeError(f'The `@{name}` decorator should be applied after `@validate_call` (put `@{name}` on top)')
         return _validate_call.ValidateCallWrapper(function, config, validate_return)  # type: ignore
 
     if __func:

tests/test_validate_call.py

@@ -1,5 +1,6 @@
 import asyncio
 import inspect
+import re
 import sys
 from datetime import datetime, timezone
 from functools import partial
@@ -687,3 +688,18 @@ def test(self, x: int):
 
     bar = Bar()
     assert bar.test('1') == (bar, 1)
+
+
+@pytest.mark.parametrize('decorator', [staticmethod, classmethod])
+def test_classmethod_order_error(decorator):
+    name = decorator.__name__
+    with pytest.raises(
+        TypeError,
+        match=re.escape(f'The `@{name}` decorator should be applied after `@validate_call` (put `@{name}` on top)'),
+    ):
+
+        class A:
+            @validate_call
+            @decorator
+            def method(self, x: int):
+                pass