Rename Parameter#arg and ParameterWithDefault#def fields (#6255)

## Summary

This PR renames...

- `Parameter#arg` to `Parameter#name`
- `ParameterWithDefault#def` to `ParameterWithDefault#parameter` (such
that `ParameterWithDefault` has a `default` and a `parameter`)

## Test Plan

`cargo test`

crates/ruff_python_ast/src/comparable.rs

@@ -381,7 +381,7 @@ pub struct ComparableParameter<'a> {
 impl<'a> From<&'a ast::Parameter> for ComparableParameter<'a> {
     fn from(arg: &'a ast::Parameter) -> Self {
         Self {
-            arg: arg.arg.as_str(),
+            arg: arg.name.as_str(),
             annotation: arg.annotation.as_ref().map(Into::into),
         }
     }
@@ -396,7 +396,7 @@ pub struct ComparableParameterWithDefault<'a> {
 impl<'a> From<&'a ast::ParameterWithDefault> for ComparableParameterWithDefault<'a> {
     fn from(arg: &'a ast::ParameterWithDefault) -> Self {
         Self {
-            def: (&arg.def).into(),
+            def: (&arg.parameter).into(),
             default: arg.default.as_ref().map(Into::into),
         }
     }

crates/ruff_python_ast/src/helpers.rs

@@ -370,7 +370,7 @@ where
                         .as_ref()
                         .is_some_and(|expr| any_over_expr(expr, func))
                         || parameter
-                            .def
+                            .parameter
                             .annotation
                             .as_ref()
                             .is_some_and(|expr| any_over_expr(expr, func))
@@ -719,17 +719,17 @@ pub fn includes_arg_name(name: &str, parameters: &Parameters) -> bool {
         .iter()
         .chain(&parameters.args)
         .chain(&parameters.kwonlyargs)
-        .any(|arg| arg.def.arg.as_str() == name)
+        .any(|arg| arg.parameter.name.as_str() == name)
     {
         return true;
     }
     if let Some(arg) = &parameters.vararg {
-        if arg.arg.as_str() == name {
+        if arg.name.as_str() == name {
             return true;
         }
     }
     if let Some(arg) = &parameters.kwarg {
-        if arg.arg.as_str() == name {
+        if arg.name.as_str() == name {
             return true;
         }
     }

crates/ruff_python_ast/src/identifier.rs

@@ -47,7 +47,7 @@ impl Identifier for Parameter {
     ///     ...
     /// ```
     fn identifier(&self) -> TextRange {
-        self.arg.range()
+        self.name.range()
     }
 }
 
@@ -60,7 +60,7 @@ impl Identifier for ParameterWithDefault {
     ///     ...
     /// ```
     fn identifier(&self) -> TextRange {
-        self.def.identifier()
+        self.parameter.identifier()
     }
 }
 

crates/ruff_python_ast/src/nodes.rs

@@ -1826,7 +1826,7 @@ impl From<ExceptHandlerExceptHandler> for ExceptHandler {
 #[derive(Clone, Debug, PartialEq)]
 pub struct Parameter {
     pub range: TextRange,
-    pub arg: Identifier,
+    pub name: Identifier,
     pub annotation: Option<Box<Expr>>,
 }
 
@@ -2069,7 +2069,7 @@ pub struct Parameters {
 #[derive(Clone, Debug, PartialEq)]
 pub struct ParameterWithDefault {
     pub range: TextRange,
-    pub def: Parameter,
+    pub parameter: Parameter,
     pub default: Option<Box<Expr>>,
 }
 
@@ -2113,24 +2113,24 @@ fn clone_boxed_expr(expr: &Box<Expr>) -> Box<Expr> {
 
 impl ParameterWithDefault {
     pub fn as_parameter(&self) -> &Parameter {
-        &self.def
+        &self.parameter
     }
 
     pub fn to_parameter(&self) -> (Parameter, Option<Box<Expr>>) {
         let ParameterWithDefault {
             range: _,
-            def,
+            parameter,
             default,
         } = self;
-        (def.clone(), default.as_ref().map(clone_boxed_expr))
+        (parameter.clone(), default.as_ref().map(clone_boxed_expr))
     }
     pub fn into_parameter(self) -> (Parameter, Option<Box<Expr>>) {
         let ParameterWithDefault {
             range: _,
-            def,
+            parameter,
             default,
         } = self;
-        (def, default)
+        (parameter, default)
     }
 }
 

crates/ruff_python_ast/src/visitor.rs

@@ -664,16 +664,16 @@ pub fn walk_parameters<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, parameters:
     }
 
     for arg in &parameters.posonlyargs {
-        visitor.visit_parameter(&arg.def);
+        visitor.visit_parameter(&arg.parameter);
     }
     for arg in &parameters.args {
-        visitor.visit_parameter(&arg.def);
+        visitor.visit_parameter(&arg.parameter);
     }
     if let Some(arg) = &parameters.vararg {
         visitor.visit_parameter(arg);
     }
     for arg in &parameters.kwonlyargs {
-        visitor.visit_parameter(&arg.def);
+        visitor.visit_parameter(&arg.parameter);
     }
     if let Some(arg) = &parameters.kwarg {
         visitor.visit_parameter(arg);

crates/ruff_python_ast/src/visitor/preorder.rs

@@ -785,7 +785,7 @@ pub fn walk_parameter_with_default<'a, V>(
 ) where
     V: PreorderVisitor<'a> + ?Sized,
 {
-    visitor.visit_parameter(&parameter_with_default.def);
+    visitor.visit_parameter(&parameter_with_default.parameter);
     if let Some(expr) = &parameter_with_default.default {
         visitor.visit_expr(expr);
     }