Remove unnecessary boxing of ASDL product children

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

ast/asdl_rs.py

@@ -89,6 +89,7 @@ class TypeInfo:
         self.has_userdata = None
         self.children = set()
         self.boxed = False
+        self.product = False
 
     def __repr__(self):
         return f"<TypeInfo: {self.name}>"
@@ -145,6 +146,7 @@ class FindUserdataTypesVisitor(asdl.VisitorBase):
             info.has_userdata = True
         if len(product.fields) > 2:
             info.boxed = True
+        info.product = True
         self.add_children(name, product.fields)
 
     def add_children(self, name, fields):
@@ -236,7 +238,7 @@ class StructVisitor(TypeInfoEmitVisitor):
         if fieldtype and fieldtype.has_userdata:
             typ = f"{typ}<U>"
         # don't box if we're doing Vec<T>, but do box if we're doing Vec<Option<Box<T>>>
-        if fieldtype and fieldtype.boxed and (not field.seq or field.opt):
+        if fieldtype and fieldtype.boxed and (not (parent.product or field.seq) or field.opt):
             typ = f"Box<{typ}>"
         if field.opt:
             typ = f"Option<{typ}>"

ast/src/ast_gen.rs

@@ -337,8 +337,8 @@ pub enum Cmpop {
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct Comprehension<U = ()> {
-    pub target: Box<Expr<U>>,
-    pub iter: Box<Expr<U>>,
+    pub target: Expr<U>,
+    pub iter: Expr<U>,
     pub ifs: Vec<Expr<U>>,
     pub is_async: usize,
 }
@@ -375,7 +375,7 @@ pub type Arg<U = ()> = Located<ArgData<U>, U>;
 #[derive(Clone, Debug, PartialEq)]
 pub struct KeywordData<U = ()> {
     pub arg: Option<Ident>,
-    pub value: Box<Expr<U>>,
+    pub value: Expr<U>,
 }
 pub type Keyword<U = ()> = Located<KeywordData<U>, U>;
 
@@ -388,13 +388,13 @@ pub type Alias<U = ()> = Located<AliasData, U>;
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct Withitem<U = ()> {
-    pub context_expr: Box<Expr<U>>,
+    pub context_expr: Expr<U>,
     pub optional_vars: Option<Box<Expr<U>>>,
 }
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct MatchCase<U = ()> {
-    pub pattern: Box<Pattern<U>>,
+    pub pattern: Pattern<U>,
     pub guard: Option<Box<Expr<U>>>,
     pub body: Vec<Stmt<U>>,
 }

parser/python.lalrpop

@@ -520,12 +520,12 @@ WithItems: Vec<ast::Withitem> = {
     <items:TestAs<ExprOrWithitemsGoal>> =>? items.try_into(),
     <first:TestAs<ExprOrWithitemsGoal>> "as" <vars:Expression> =>? {
         let optional_vars = Some(Box::new(set_context(vars, ast::ExprContext::Store)));
-        let context_expr = Box::new(first.try_into()?);
+        let context_expr = first.try_into()?;
         Ok(vec![ast::Withitem { context_expr, optional_vars }])
     },
     <first:TestAs<ExprOrWithitemsGoal>> <n:("as" Expression)?> "," <mut items:OneOrMore<WithItem>> =>? {
         let optional_vars = n.map(|val| Box::new(set_context(val.1, ast::ExprContext::Store)));
-        let context_expr = Box::new(first.try_into()?);
+        let context_expr = first.try_into()?;
         items.insert(0, ast::Withitem { context_expr, optional_vars });
         Ok(items)
     }
@@ -534,7 +534,6 @@ WithItems: Vec<ast::Withitem> = {
 WithItem: ast::Withitem = {
     <context_expr:Test> <n:("as" Expression)?> => {
         let optional_vars = n.map(|val| Box::new(set_context(val.1, ast::ExprContext::Store)));
-        let context_expr = Box::new(context_expr);
         ast::Withitem { context_expr, optional_vars }
     },
 };
@@ -1280,8 +1279,8 @@ SingleForComprehension: ast::Comprehension = {
     <location:@L> <is_async:"async"?> "for" <target:ExpressionList> "in" <iter:OrTest> <ifs:ComprehensionIf*> <end_location:@R> => {
         let is_async = is_async.is_some();
         ast::Comprehension {
-            target: Box::new(set_context(target, ast::ExprContext::Store)),
-            iter: Box::new(iter),
+            target: set_context(target, ast::ExprContext::Store),
+            iter,
             ifs,
             is_async: if is_async { 1 } else { 0 },
         }

parser/src/function.rs

@@ -72,10 +72,7 @@ pub fn parse_args(func_args: Vec<FunctionArgument>) -> Result<ArgumentList, Lexi
                 keywords.push(ast::Keyword::new(
                     start,
                     end,
-                    ast::KeywordData {
-                        arg: name,
-                        value: Box::new(value),
-                    },
+                    ast::KeywordData { arg: name, value },
                 ));
             }
             None => {

parser/src/with.rs

@@ -117,7 +117,7 @@ impl TryFrom<ExprOrWithitems> for Vec<ast::Withitem> {
                     .items
                     .into_iter()
                     .map(|(context_expr, optional_vars)| ast::Withitem {
-                        context_expr: Box::new(context_expr),
+                        context_expr,
                         optional_vars: optional_vars.map(|expr| {
                             Box::new(context::set_context(*expr, ast::ExprContext::Store))
                         }),
@@ -125,7 +125,7 @@ impl TryFrom<ExprOrWithitems> for Vec<ast::Withitem> {
                     .collect())
             }
             _ => Ok(vec![ast::Withitem {
-                context_expr: Box::new(expr_or_withitems.try_into()?),
+                context_expr: expr_or_withitems.try_into()?,
                 optional_vars: None,
             }]),
         }