Remove implicit recursive cloning of AST

wasm/src/ast/builder.rs

@@ -212,7 +212,9 @@ impl<'a> Builder<'a> {
 	// Pending expressions are put to sleep before entering
 	// a control structure so that they are not lost.
 	fn save_pending(&mut self) {
-		self.pending.push(self.stack.clone());
+		let cloned = self.stack.iter().map(Expression::clone_recall).collect();
+
+		self.pending.push(cloned);
 	}
 
 	fn load_pending(&mut self) {
@@ -456,7 +458,7 @@ impl<'a> Builder<'a> {
 				Inst::TeeLocal(i) => {
 					self.gen_leak_pending(&mut stat);
 
-					let value = self.stack.last().unwrap().clone();
+					let value = self.stack.last().unwrap().clone_recall();
 
 					stat.push(Statement::SetLocal(SetLocal { var: *i, value }));
 				}

wasm/src/ast/node.rs

@@ -9,36 +9,30 @@ pub struct Recall {
 	pub var: usize,
 }
 
-#[derive(Clone)]
 pub struct Select {
 	pub cond: Box<Expression>,
 	pub a: Box<Expression>,
 	pub b: Box<Expression>,
 }
 
-#[derive(Clone)]
 pub struct GetLocal {
 	pub var: u32,
 }
 
-#[derive(Clone)]
 pub struct GetGlobal {
 	pub var: u32,
 }
 
-#[derive(Clone)]
 pub struct AnyLoad {
 	pub op: Load,
 	pub offset: u32,
 	pub pointer: Box<Expression>,
 }
 
-#[derive(Clone)]
 pub struct MemorySize {
 	pub memory: u8,
 }
 
-#[derive(Clone)]
 pub struct MemoryGrow {
 	pub memory: u8,
 	pub value: Box<Expression>,
@@ -52,20 +46,17 @@ pub enum Value {
 	F64(f64),
 }
 
-#[derive(Clone)]
 pub struct AnyUnOp {
 	pub op: UnOp,
 	pub rhs: Box<Expression>,
 }
 
-#[derive(Clone)]
 pub struct AnyBinOp {
 	pub op: BinOp,
 	pub lhs: Box<Expression>,
 	pub rhs: Box<Expression>,
 }
 
-#[derive(Clone)]
 pub enum Expression {
 	Recall(Recall),
 	Select(Select),
@@ -86,6 +77,13 @@ impl Expression {
 			_ => false,
 		}
 	}
+
+	pub fn clone_recall(&self) -> Self {
+		match self {
+			Expression::Recall(v) => Expression::Recall(v.clone()),
+			_ => unreachable!("clone_recall called on non-recall"),
+		}
+	}
 }
 
 pub struct Memorize {