fix grammar

Author: AlexWaygood

crates/ty_python_semantic/resources/mdtest/snapshots/liskov.md_-_The_Liskov_Substitut…_-_Staticmethods_and_cl…_(49e28aae6fdd1291).snap

@@ -85,7 +85,7 @@ error[invalid-method-override]: Invalid override of method `instance_method`
  3 |     @classmethod
  4 |     def class_method(cls, x: int) -> int: ...
    |
-info: `BadChild1.instance_method` is a staticmethod but `Parent.instance_method` is a instance method
+info: `BadChild1.instance_method` is a staticmethod but `Parent.instance_method` is an instance method
 info: This violates the Liskov Substitution Principle
 info: rule `invalid-method-override` is enabled by default
 
@@ -111,7 +111,7 @@ error[invalid-method-override]: Invalid override of method `static_method`
  7 |
  8 | class BadChild1(Parent):
    |
-info: `BadChild1.static_method` is a instance method but `Parent.static_method` is a staticmethod
+info: `BadChild1.static_method` is an instance method but `Parent.static_method` is a staticmethod
 info: This violates the Liskov Substitution Principle
 info: rule `invalid-method-override` is enabled by default
 

crates/ty_python_semantic/src/types/class.rs

@@ -1258,21 +1258,15 @@ impl MethodDecorator {
         }
     }
 
-    pub(crate) const fn as_str(self) -> &'static str {
+    pub(crate) const fn description(self) -> &'static str {
         match self {
-            MethodDecorator::None => "instance method",
-            MethodDecorator::ClassMethod => "classmethod",
-            MethodDecorator::StaticMethod => "staticmethod",
+            MethodDecorator::None => "an instance method",
+            MethodDecorator::ClassMethod => "a classmethod",
+            MethodDecorator::StaticMethod => "a staticmethod",
         }
     }
 }
 
-impl std::fmt::Display for MethodDecorator {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.write_str(self.as_str())
-    }
-}
-
 /// Kind-specific metadata for different types of fields
 #[derive(Debug, Clone, PartialEq, Eq, salsa::Update, get_size2::GetSize)]
 pub(crate) enum FieldKind<'db> {

crates/ty_python_semantic/src/types/diagnostic.rs

@@ -3534,8 +3534,10 @@ pub(super) fn report_invalid_method_override<'db>(
         && superclass_function_kind != subclass_function_kind
     {
         diagnostic.info(format_args!(
-            "`{class_name}.{member}` is a {subclass_function_kind} \
-            but `{overridden_method}` is a {superclass_function_kind}"
+            "`{class_name}.{member}` is {subclass_function_kind} \
+            but `{overridden_method}` is {superclass_function_kind}",
+            superclass_function_kind = superclass_function_kind.description(),
+            subclass_function_kind = subclass_function_kind.description(),
         ));
     }