Reduce explcit clones (#3793)

crates/ruff_python_ast/src/branch_detection.rs

@@ -8,40 +8,39 @@ use crate::types::RefEquality;
 
 /// Return the common ancestor of `left` and `right` below `stop`, or `None`.
 fn common_ancestor<'a>(
-    left: &'a RefEquality<'a, Stmt>,
-    right: &'a RefEquality<'a, Stmt>,
-    stop: Option<&'a RefEquality<'a, Stmt>>,
+    left: RefEquality<'a, Stmt>,
+    right: RefEquality<'a, Stmt>,
+    stop: Option<RefEquality<'a, Stmt>>,
     depths: &'a FxHashMap<RefEquality<'a, Stmt>, usize>,
     child_to_parent: &'a FxHashMap<RefEquality<'a, Stmt>, RefEquality<'a, Stmt>>,
-) -> Option<&'a RefEquality<'a, Stmt>> {
-    if let Some(stop) = stop {
-        if left == stop || right == stop {
-            return None;
-        }
+) -> Option<RefEquality<'a, Stmt>> {
+    if Some(left) == stop || Some(right) == stop {
+        return None;
     }
+
     if left == right {
         return Some(left);
     }
 
-    let left_depth = depths.get(left)?;
-    let right_depth = depths.get(right)?;
+    let left_depth = depths.get(&left)?;
+    let right_depth = depths.get(&right)?;
     match left_depth.cmp(right_depth) {
         Ordering::Less => common_ancestor(
             left,
-            child_to_parent.get(right)?,
+            *child_to_parent.get(&right)?,
             stop,
             depths,
             child_to_parent,
         ),
         Ordering::Equal => common_ancestor(
-            child_to_parent.get(left)?,
-            child_to_parent.get(right)?,
+            *child_to_parent.get(&left)?,
+            *child_to_parent.get(&right)?,
             stop,
             depths,
             child_to_parent,
         ),
         Ordering::Greater => common_ancestor(
-            child_to_parent.get(left)?,
+            *child_to_parent.get(&left)?,
             right,
             stop,
             depths,
@@ -51,8 +50,8 @@ fn common_ancestor<'a>(
 }
 
 /// Return the alternative branches for a given node.
-fn alternatives<'a>(stmt: &'a RefEquality<'a, Stmt>) -> Vec<Vec<RefEquality<'a, Stmt>>> {
-    match &stmt.node {
+fn alternatives(stmt: RefEquality<Stmt>) -> Vec<Vec<RefEquality<Stmt>>> {
+    match &stmt.as_ref().node {
         StmtKind::If { body, .. } => vec![body.iter().map(RefEquality).collect()],
         StmtKind::Try {
             body,
@@ -78,22 +77,22 @@ fn alternatives<'a>(stmt: &'a RefEquality<'a, Stmt>) -> Vec<Vec<RefEquality<'a,
 
 /// Return `true` if `stmt` is a descendent of any of the nodes in `ancestors`.
 fn descendant_of<'a>(
-    stmt: &RefEquality<'a, Stmt>,
+    stmt: RefEquality<'a, Stmt>,
     ancestors: &[RefEquality<'a, Stmt>],
-    stop: &RefEquality<'a, Stmt>,
+    stop: RefEquality<'a, Stmt>,
     depths: &FxHashMap<RefEquality<'a, Stmt>, usize>,
     child_to_parent: &FxHashMap<RefEquality<'a, Stmt>, RefEquality<'a, Stmt>>,
 ) -> bool {
     ancestors.iter().any(|ancestor| {
-        common_ancestor(stmt, ancestor, Some(stop), depths, child_to_parent).is_some()
+        common_ancestor(stmt, *ancestor, Some(stop), depths, child_to_parent).is_some()
     })
 }
 
 /// Return `true` if `left` and `right` are on different branches of an `if` or
 /// `try` statement.
 pub fn different_forks<'a>(
-    left: &RefEquality<'a, Stmt>,
-    right: &RefEquality<'a, Stmt>,
+    left: RefEquality<'a, Stmt>,
+    right: RefEquality<'a, Stmt>,
     depths: &FxHashMap<RefEquality<'a, Stmt>, usize>,
     child_to_parent: &FxHashMap<RefEquality<'a, Stmt>, RefEquality<'a, Stmt>>,
 ) -> bool {

crates/ruff_python_ast/src/comparable.rs

@@ -9,7 +9,7 @@ use rustpython_parser::ast::{
 
 use num_bigint::BigInt;
 
-#[derive(Debug, PartialEq, Eq, Hash)]
+#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
 pub enum ComparableExprContext {
     Load,
     Store,
@@ -26,7 +26,7 @@ impl From<&ExprContext> for ComparableExprContext {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Hash)]
+#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
 pub enum ComparableBoolop {
     And,
     Or,
@@ -41,7 +41,7 @@ impl From<&Boolop> for ComparableBoolop {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Hash)]
+#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
 pub enum ComparableOperator {
     Add,
     Sub,
@@ -78,7 +78,7 @@ impl From<&Operator> for ComparableOperator {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Hash)]
+#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
 pub enum ComparableUnaryop {
     Invert,
     Not,
@@ -97,7 +97,7 @@ impl From<&Unaryop> for ComparableUnaryop {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Hash)]
+#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone)]
 pub enum ComparableCmpop {
     Eq,
     NotEq,

crates/ruff_python_ast/src/context.rs

@@ -206,13 +206,10 @@ impl<'a> Context<'a> {
     pub fn push_parent(&mut self, parent: &'a Stmt) {
         let num_existing = self.parents.len();
         self.parents.push(RefEquality(parent));
-        self.depths
-            .insert(self.parents[num_existing].clone(), num_existing);
+        self.depths.insert(self.parents[num_existing], num_existing);
         if num_existing > 0 {
-            self.child_to_parent.insert(
-                self.parents[num_existing].clone(),
-                self.parents[num_existing - 1].clone(),
-            );
+            self.child_to_parent
+                .insert(self.parents[num_existing], self.parents[num_existing - 1]);
         }
     }
 

crates/ruff_python_ast/src/function_type.rs

@@ -7,6 +7,7 @@ use crate::scope::{Scope, ScopeKind};
 const CLASS_METHODS: [&str; 3] = ["__new__", "__init_subclass__", "__class_getitem__"];
 const METACLASS_BASES: [(&str, &str); 2] = [("", "type"), ("abc", "ABCMeta")];
 
+#[derive(Copy, Clone)]
 pub enum FunctionType {
     Function,
     Method,

crates/ruff_python_ast/src/logging.rs

@@ -1,3 +1,4 @@
+#[derive(Copy, Clone)]
 pub enum LoggingLevel {
     Debug,
     Critical,

crates/ruff_python_ast/src/scope.rs

@@ -215,8 +215,19 @@ impl ScopeStack {
     pub fn iter(&self) -> std::iter::Rev<std::slice::Iter<ScopeId>> {
         self.0.iter().rev()
     }
+
+    pub fn snapshot(&self) -> ScopeStackSnapshot {
+        ScopeStackSnapshot(self.0.len())
+    }
+
+    #[allow(clippy::needless_pass_by_value)]
+    pub fn restore(&mut self, snapshot: ScopeStackSnapshot) {
+        self.0.truncate(snapshot.0);
+    }
 }
 
+pub struct ScopeStackSnapshot(usize);
+
 impl Default for ScopeStack {
     fn default() -> Self {
         Self(vec![ScopeId::global()])

crates/ruff_python_ast/src/source_code/generator.rs

@@ -65,7 +65,7 @@ pub struct Generator<'a> {
     /// The quote style to use for string literals.
     quote: Quote,
     /// The line ending to use.
-    line_ending: &'a LineEnding,
+    line_ending: LineEnding,
     buffer: String,
     indent_depth: usize,
     num_newlines: usize,
@@ -87,7 +87,7 @@ impl<'a> From<&'a Stylist<'a>> for Generator<'a> {
 }
 
 impl<'a> Generator<'a> {
-    pub const fn new(indent: &'a Indentation, quote: Quote, line_ending: &'a LineEnding) -> Self {
+    pub const fn new(indent: &'a Indentation, quote: Quote, line_ending: LineEnding) -> Self {
         Self {
             // Style preferences.
             indent,
@@ -128,7 +128,7 @@ impl<'a> Generator<'a> {
     fn p(&mut self, s: &str) {
         if self.num_newlines > 0 {
             for _ in 0..self.num_newlines {
-                self.buffer += self.line_ending;
+                self.buffer += &self.line_ending;
             }
             self.num_newlines = 0;
         }
@@ -1266,7 +1266,7 @@ mod tests {
         let line_ending = LineEnding::default();
         let program = parser::parse_program(contents, "<filename>").unwrap();
         let stmt = program.first().unwrap();
-        let mut generator = Generator::new(&indentation, quote, &line_ending);
+        let mut generator = Generator::new(&indentation, quote, line_ending);
         generator.unparse_stmt(stmt);
         generator.generate()
     }
@@ -1274,7 +1274,7 @@ mod tests {
     fn round_trip_with(
         indentation: &Indentation,
         quote: Quote,
-        line_ending: &LineEnding,
+        line_ending: LineEnding,
         contents: &str,
     ) -> String {
         let program = parser::parse_program(contents, "<filename>").unwrap();
@@ -1449,7 +1449,7 @@ if True:
             round_trip_with(
                 &Indentation::default(),
                 Quote::Double,
-                &LineEnding::default(),
+                LineEnding::default(),
                 r#""hello""#
             ),
             r#""hello""#
@@ -1458,7 +1458,7 @@ if True:
             round_trip_with(
                 &Indentation::default(),
                 Quote::Single,
-                &LineEnding::default(),
+                LineEnding::default(),
                 r#""hello""#
             ),
             r#"'hello'"#
@@ -1467,7 +1467,7 @@ if True:
             round_trip_with(
                 &Indentation::default(),
                 Quote::Double,
-                &LineEnding::default(),
+                LineEnding::default(),
                 r#"'hello'"#
             ),
             r#""hello""#
@@ -1476,7 +1476,7 @@ if True:
             round_trip_with(
                 &Indentation::default(),
                 Quote::Single,
-                &LineEnding::default(),
+                LineEnding::default(),
                 r#"'hello'"#
             ),
             r#"'hello'"#
@@ -1489,7 +1489,7 @@ if True:
             round_trip_with(
                 &Indentation::new("    ".to_string()),
                 Quote::default(),
-                &LineEnding::default(),
+                LineEnding::default(),
                 r#"
 if True:
   pass
@@ -1507,7 +1507,7 @@ if True:
             round_trip_with(
                 &Indentation::new("  ".to_string()),
                 Quote::default(),
-                &LineEnding::default(),
+                LineEnding::default(),
                 r#"
 if True:
   pass
@@ -1525,7 +1525,7 @@ if True:
             round_trip_with(
                 &Indentation::new("\t".to_string()),
                 Quote::default(),
-                &LineEnding::default(),
+                LineEnding::default(),
                 r#"
 if True:
   pass
@@ -1547,7 +1547,7 @@ if True:
             round_trip_with(
                 &Indentation::default(),
                 Quote::default(),
-                &LineEnding::Lf,
+                LineEnding::Lf,
                 "if True:\n    print(42)",
             ),
             "if True:\n    print(42)",
@@ -1557,7 +1557,7 @@ if True:
             round_trip_with(
                 &Indentation::default(),
                 Quote::default(),
-                &LineEnding::CrLf,
+                LineEnding::CrLf,
                 "if True:\n    print(42)",
             ),
             "if True:\r\n    print(42)",
@@ -1567,7 +1567,7 @@ if True:
             round_trip_with(
                 &Indentation::default(),
                 Quote::default(),
-                &LineEnding::Cr,
+                LineEnding::Cr,
                 "if True:\n    print(42)",
             ),
             "if True:\r    print(42)",

crates/ruff_python_ast/src/source_code/stylist.rs

@@ -56,8 +56,9 @@ impl<'a> Stylist<'a> {
         })
     }
 
-    pub fn line_ending(&'a self) -> &'a LineEnding {
-        self.line_ending
+    pub fn line_ending(&'a self) -> LineEnding {
+        *self
+            .line_ending
             .get_or_init(|| detect_line_ending(self.locator.contents()).unwrap_or_default())
     }
 
@@ -160,7 +161,7 @@ impl Deref for Indentation {
 
 /// The line ending style used in Python source code.
 /// See <https://docs.python.org/3/reference/lexical_analysis.html#physical-lines>
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum LineEnding {
     Lf,
     Cr,

crates/ruff_python_ast/src/types.rs

@@ -35,9 +35,32 @@ impl<T> From<&Box<Located<T>>> for Range {
     }
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug)]
 pub struct RefEquality<'a, T>(pub &'a T);
 
+impl<'a, T> RefEquality<'a, T> {
+    // More specific implementation that keeps the `'a` lifetime.
+    // It's otherwise the same as [`AsRef::as_ref`]
+    #[allow(clippy::should_implement_trait)]
+    pub fn as_ref(&self) -> &'a T {
+        self.0
+    }
+}
+
+impl<'a, T> AsRef<T> for RefEquality<'a, T> {
+    fn as_ref(&self) -> &T {
+        self.0
+    }
+}
+
+impl<'a, T> Clone for RefEquality<'a, T> {
+    fn clone(&self) -> Self {
+        Self(self.0)
+    }
+}
+
+impl<'a, T> Copy for RefEquality<'a, T> {}
+
 impl<'a, T> std::hash::Hash for RefEquality<'a, T> {
     fn hash<H>(&self, state: &mut H)
     where

crates/ruff_python_ast/src/typing.rs

@@ -10,6 +10,7 @@ use crate::source_code::Locator;
 use crate::str;
 use crate::types::Range;
 
+#[derive(Copy, Clone)]
 pub enum Callable {
     Cast,
     NewType,
@@ -19,6 +20,7 @@ pub enum Callable {
     MypyExtension,
 }
 
+#[derive(Copy, Clone)]
 pub enum SubscriptKind {
     AnnotatedSubscript,
     PEP593AnnotatedSubscript,
@@ -72,7 +74,7 @@ pub fn is_pep585_builtin(expr: &Expr, context: &Context) -> bool {
     })
 }
 
-#[derive(is_macro::Is)]
+#[derive(is_macro::Is, Copy, Clone)]
 pub enum AnnotationKind {
     /// The annotation is defined as part a simple string literal,
     /// e.g. `x: "List[int]" = []`. Annotations within simple literals

crates/ruff_python_ast/src/visibility.rs

@@ -6,20 +6,20 @@ use crate::context::Context;
 use crate::helpers::{collect_call_path, map_callable};
 use crate::types::CallPath;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy)]
 pub enum Modifier {
     Module,
     Class,
     Function,
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy)]
 pub enum Visibility {
     Public,
     Private,
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy)]
 pub struct VisibleScope {
     pub modifier: Modifier,
     pub visibility: Visibility,