Fix labelled block statement (#2285)

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This Pull Request fixes [x-after-break-to-label](https://github.com/tc39/test262/blob/dc1dc28aa46d9457e47550b34e6f25a8b80de826/test/language/block-scope/leave/x-after-break-to-label.js)

### Example
```js
{
  let x = 2;
  L: {
    let x = 3;
    console.log(x === 3);
    break L;
    console.log(false);
  }
  console.log(x === 2);
}
```

### Previously
> Uncaught "SyntaxError": "Cannot use the undeclared label 'L'"

### Now
> true <br> true

### What did I do
1. add `lable` to `Node::Block`
2. push labelled-block's `control info` to `jump_info` list
3. pop it before `Opcode::PopEnvironment`

Co-authored-by: creampnx_x <[email protected]>

boa_engine/src/bytecompiler/mod.rs

@@ -57,6 +57,7 @@ enum JumpControlInfoKind {
     Loop,
     Switch,
     Try,
+    LabelledBlock,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -491,6 +492,36 @@ impl<'b> ByteCompiler<'b> {
         }
     }
 
+    #[inline]
+    fn push_labelled_block_control_info(&mut self, label: Sym, start_address: u32) {
+        self.jump_info.push(JumpControlInfo {
+            label: Some(label),
+            start_address,
+            kind: JumpControlInfoKind::LabelledBlock,
+            breaks: Vec::new(),
+            try_continues: Vec::new(),
+            in_catch: false,
+            has_finally: false,
+            finally_start: None,
+            for_of_in_loop: false,
+        });
+    }
+
+    #[inline]
+    fn pop_labelled_block_control_info(&mut self) {
+        let info = self.jump_info.pop().expect("no jump information found");
+
+        assert!(info.kind == JumpControlInfoKind::LabelledBlock);
+
+        for label in info.breaks {
+            self.patch_jump(label);
+        }
+
+        for label in info.try_continues {
+            self.patch_jump_with_target(label, info.start_address);
+        }
+    }
+
     #[inline]
     fn compile_access(node: &Node) -> Option<Access<'_>> {
         match node {
@@ -1797,6 +1828,11 @@ impl<'b> ByteCompiler<'b> {
                 }
             }
             Node::Block(block) => {
+                if let Some(label) = block.label() {
+                    let next = self.next_opcode_location();
+                    self.push_labelled_block_control_info(label, next);
+                }
+
                 self.context.push_compile_time_environment(false);
                 let push_env =
                     self.emit_opcode_with_two_operands(Opcode::PushDeclarativeEnvironment);
@@ -1807,6 +1843,11 @@ impl<'b> ByteCompiler<'b> {
                 let index_compile_environment = self.push_compile_environment(compile_environment);
                 self.patch_jump_with_target(push_env.0, num_bindings as u32);
                 self.patch_jump_with_target(push_env.1, index_compile_environment as u32);
+
+                if block.label().is_some() {
+                    self.pop_labelled_block_control_info();
+                }
+
                 self.emit_opcode(Opcode::PopEnvironment);
             }
             Node::Throw(throw) => {

boa_engine/src/syntax/ast/node/block/mod.rs

@@ -25,11 +25,11 @@ mod tests;
 /// [spec]: https://tc39.es/ecma262/#prod-BlockStatement
 /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/block
 #[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
-#[cfg_attr(feature = "deser", serde(transparent))]
 #[derive(Clone, Debug, PartialEq)]
 pub struct Block {
     #[cfg_attr(feature = "deser", serde(flatten))]
     statements: StatementList,
+    label: Option<Sym>,
 }
 
 impl Block {
@@ -52,6 +52,14 @@ impl Block {
             "    ".repeat(indentation)
         )
     }
+
+    pub fn label(&self) -> Option<Sym> {
+        self.label
+    }
+
+    pub fn set_label(&mut self, label: Sym) {
+        self.label = Some(label);
+    }
 }
 
 impl<T> From<T> for Block
@@ -61,6 +69,7 @@ where
     fn from(list: T) -> Self {
         Self {
             statements: list.into(),
+            label: None,
         }
     }
 }

boa_engine/src/syntax/parser/statement/labelled_stm/mod.rs

@@ -95,6 +95,7 @@ fn set_label_for_node(node: &mut Node, name: Sym) {
         Node::ForInLoop(ref mut for_in_loop) => for_in_loop.set_label(name),
         Node::DoWhileLoop(ref mut do_while_loop) => do_while_loop.set_label(name),
         Node::WhileLoop(ref mut while_loop) => while_loop.set_label(name),
+        Node::Block(ref mut block) => block.set_label(name),
         _ => (),
     }
 }

boa_engine/src/tests.rs

@@ -1632,3 +1632,22 @@ fn test_empty_statement() {
     "#;
     assert_eq!(&exec(src), "10");
 }
+
+#[test]
+fn test_labelled_block() {
+    let src = r#"
+        let result = true;
+        {
+            let x = 2;
+            L: {
+                let x = 3;
+                result &&= (x === 3);
+                break L;
+                result &&= (false);
+            }
+            result &&= (x === 2);
+        }
+        result;
+    "#;
+    assert_eq!(&exec(src), "true");
+}