feat: support explicit-resource-management

rust/parse_ast/src/convert_ast/converter.rs

@@ -16,7 +16,7 @@ use swc_ecma_ast::{
   PropName, PropOrSpread, Regex, RestPat, ReturnStmt, SeqExpr, SetterProp, SimpleAssignTarget,
   SpreadElement, StaticBlock, Stmt, Str, Super, SuperProp, SuperPropExpr, SwitchCase, SwitchStmt,
   TaggedTpl, ThisExpr, ThrowStmt, Tpl, TplElement, TryStmt, UnaryExpr, UnaryOp, UpdateExpr,
-  UpdateOp, VarDecl, VarDeclKind, VarDeclOrExpr, VarDeclarator, WhileStmt, YieldExpr,
+  UpdateOp, UsingDecl, VarDecl, VarDeclKind, VarDeclOrExpr, VarDeclarator, WhileStmt, YieldExpr,
 };
 
 use crate::convert_ast::annotations::{AnnotationKind, AnnotationWithType};
@@ -259,14 +259,18 @@ impl<'a> AstConverter<'a> {
 
   fn convert_declaration(&mut self, declaration: &Decl) {
     match declaration {
-      Decl::Var(variable_declaration) => self.convert_variable_declaration(variable_declaration),
+      Decl::Var(variable_declaration) => {
+        self.convert_variable_declaration(&VariableDeclaration::Var(variable_declaration))
+      }
       Decl::Fn(function_declaration) => self.convert_function(
         &function_declaration.function,
         &TYPE_FUNCTION_DECLARATION_INLINED_ANNOTATIONS,
         Some(&function_declaration.ident),
       ),
       Decl::Class(class_declaration) => self.convert_class_declaration(class_declaration),
-      Decl::Using(_) => unimplemented!("Cannot convert Decl::Using"),
+      Decl::Using(using_declaration) => {
+        self.convert_variable_declaration(&VariableDeclaration::Using(using_declaration))
+      }
       Decl::TsInterface(_) => unimplemented!("Cannot convert Decl::TsInterface"),
       Decl::TsTypeAlias(_) => unimplemented!("Cannot convert Decl::TsTypeAlias"),
       Decl::TsEnum(_) => unimplemented!("Cannot convert Decl::TsEnum"),
@@ -527,12 +531,14 @@ impl<'a> AstConverter<'a> {
   fn convert_for_head(&mut self, for_head: &ForHead) {
     match for_head {
       ForHead::VarDecl(variable_declaration) => {
-        self.convert_variable_declaration(variable_declaration)
+        self.convert_variable_declaration(&VariableDeclaration::Var(variable_declaration))
       }
       ForHead::Pat(pattern) => {
         self.convert_pattern(pattern);
       }
-      ForHead::UsingDecl(_) => unimplemented!("Cannot convert ForHead::UsingDecl"),
+      ForHead::UsingDecl(using_declaration) => {
+        self.convert_variable_declaration(&VariableDeclaration::Using(using_declaration))
+      }
     }
   }
 
@@ -995,7 +1001,7 @@ impl<'a> AstConverter<'a> {
   ) {
     match variable_declaration_or_expression {
       VarDeclOrExpr::VarDecl(variable_declaration) => {
-        self.convert_variable_declaration(variable_declaration);
+        self.convert_variable_declaration(&VariableDeclaration::Var(variable_declaration));
       }
       VarDeclOrExpr::Expr(expression) => {
         self.convert_expression(expression);
@@ -2942,32 +2948,43 @@ impl<'a> AstConverter<'a> {
     self.add_end(end_position, &update_expression.span);
   }
 
-  fn convert_variable_declaration(&mut self, variable_declaration: &VarDecl) {
+  fn convert_variable_declaration(&mut self, variable_declaration: &VariableDeclaration) {
+    let (kind, span, decls): (&[u8; 4], Span, &Vec<VarDeclarator>) = match variable_declaration {
+      VariableDeclaration::Var(value) => (
+        match value.kind {
+          VarDeclKind::Var => &STRING_VAR,
+          VarDeclKind::Let => &STRING_LET,
+          VarDeclKind::Const => &STRING_CONST,
+        },
+        value.span,
+        &value.decls,
+      ),
+      &VariableDeclaration::Using(value) => (
+        if value.is_await {
+          &STRING_AWAIT_USING
+        } else {
+          &STRING_USING
+        },
+        value.span,
+        &value.decls,
+      ),
+    };
     let end_position = self.add_type_and_start(
       &TYPE_VARIABLE_DECLARATION_INLINED_DECLARATIONS,
-      &variable_declaration.span,
+      &span,
       VARIABLE_DECLARATION_RESERVED_BYTES,
-      matches!(variable_declaration.kind, VarDeclKind::Const),
+      kind == &STRING_CONST,
     );
     // declarations
-    self.convert_item_list(
-      &variable_declaration.decls,
-      |ast_converter, variable_declarator| {
-        ast_converter.convert_variable_declarator(variable_declarator);
-        true
-      },
-    );
+    self.convert_item_list(decls, |ast_converter, variable_declarator| {
+      ast_converter.convert_variable_declarator(variable_declarator);
+      true
+    });
     // kind
     let kind_position = end_position + VARIABLE_DECLARATION_KIND_OFFSET;
-    self.buffer[kind_position..kind_position + 4].copy_from_slice(
-      match variable_declaration.kind {
-        VarDeclKind::Var => &STRING_VAR,
-        VarDeclKind::Let => &STRING_LET,
-        VarDeclKind::Const => &STRING_CONST,
-      },
-    );
+    self.buffer[kind_position..kind_position + 4].copy_from_slice(kind);
     // end
-    self.add_end(end_position, &variable_declaration.span);
+    self.add_end(end_position, &span);
   }
 
   fn convert_variable_declarator(&mut self, variable_declarator: &VarDeclarator) {
@@ -3065,6 +3082,11 @@ pub fn convert_string(buffer: &mut Vec<u8>, string: &str) {
   buffer.resize(buffer.len() + additional_length, 0);
 }
 
+enum VariableDeclaration<'a> {
+  Var(&'a VarDecl),
+  Using(&'a UsingDecl),
+}
+
 enum StoredCallee<'a> {
   Expression(&'a Expr),
   Super(&'a Super),

rust/parse_ast/src/convert_ast/converter/string_constants.rs

@@ -60,3 +60,5 @@ pub const STRING_NULLISHASSIGN: [u8; 4] = 57u32.to_ne_bytes(); // ??=
 pub const STRING_PURE: [u8; 4] = 58u32.to_ne_bytes(); // pure
 pub const STRING_NOSIDEEFFECTS: [u8; 4] = 59u32.to_ne_bytes(); // noSideEffects
 pub const STRING_SOURCEMAP: [u8; 4] = 60u32.to_ne_bytes(); // sourcemap
+pub const STRING_USING: [u8; 4] = 61u32.to_ne_bytes(); // using
+pub const STRING_AWAIT_USING: [u8; 4] = 62u32.to_ne_bytes(); // await using

rust/parse_ast/src/lib.rs

@@ -25,6 +25,7 @@ pub fn parse_ast(code: String, allow_return_outside_function: bool) -> Vec<u8> {
   let syntax = Syntax::Es(EsConfig {
     allow_return_outside_function,
     import_attributes: true,
+    explicit_resource_management: true,
     ..Default::default()
   });
 

src/ast/nodes/Identifier.ts

@@ -33,13 +33,7 @@ import type { VariableKind } from './shared/VariableKinds';
 
 export type IdentifierWithVariable = Identifier & { variable: Variable };
 
-const tdzVariableKinds = {
-	__proto__: null,
-	class: true,
-	const: true,
-	let: true,
-	var: true
-};
+const tdzVariableKinds = new Set(['class', 'const', 'let', 'var', 'using', 'await using']);
 
 export default class Identifier extends NodeBase implements PatternNode {
 	declare name: string;
@@ -92,6 +86,8 @@ export default class Identifier extends NodeBase implements PatternNode {
 			}
 			case 'let':
 			case 'const':
+			case 'using':
+			case 'await using':
 			case 'class': {
 				variable = this.scope.addDeclaration(this, this.scope.context, init, kind);
 				break;
@@ -221,7 +217,7 @@ export default class Identifier extends NodeBase implements PatternNode {
 			!(
 				this.variable instanceof LocalVariable &&
 				this.variable.kind &&
-				this.variable.kind in tdzVariableKinds &&
+				tdzVariableKinds.has(this.variable.kind) &&
 				// we ignore possible TDZs due to circular module dependencies as
 				// otherwise we get many false positives
 				this.variable.module === this.scope.context.module

src/ast/nodes/VariableDeclaration.ts

@@ -45,6 +45,7 @@ export default class VariableDeclaration extends NodeBase {
 	declare declarations: readonly VariableDeclarator[];
 	declare kind: VariableDeclarationKind;
 	declare type: NodeType.tVariableDeclaration;
+	declare isUsingDeclaration: boolean;
 
 	deoptimizePath(): void {
 		for (const declarator of this.declarations) {
@@ -82,8 +83,9 @@ export default class VariableDeclaration extends NodeBase {
 
 	initialise(): void {
 		super.initialise();
+		this.isUsingDeclaration = this.kind === 'await using' || this.kind === 'using';
 		for (const declarator of this.declarations) {
-			declarator.declareDeclarator(this.kind);
+			declarator.declareDeclarator(this.kind, this.isUsingDeclaration);
 		}
 	}
 
@@ -97,6 +99,7 @@ export default class VariableDeclaration extends NodeBase {
 		nodeRenderOptions: NodeRenderOptions = BLANK
 	): void {
 		if (
+			this.isUsingDeclaration ||
 			areAllDeclarationsIncludedAndNotExported(this.declarations, options.exportNamesByVariable)
 		) {
 			for (const declarator of this.declarations) {

src/ast/nodes/VariableDeclarator.ts

@@ -20,8 +20,10 @@ export default class VariableDeclarator extends NodeBase {
 	declare id: PatternNode;
 	declare init: ExpressionNode | null;
 	declare type: NodeType.tVariableDeclarator;
+	declare isUsingDeclaration: boolean;
 
-	declareDeclarator(kind: VariableKind): void {
+	declareDeclarator(kind: VariableKind, isUsingDeclaration: boolean): void {
+		this.isUsingDeclaration = isUsingDeclaration;
 		this.id.declare(kind, this.init || UNDEFINED_EXPRESSION);
 	}
 
@@ -33,7 +35,7 @@ export default class VariableDeclarator extends NodeBase {
 		if (!this.deoptimized) this.applyDeoptimizations();
 		const initEffect = this.init?.hasEffects(context);
 		this.id.markDeclarationReached();
-		return initEffect || this.id.hasEffects(context);
+		return initEffect || this.id.hasEffects(context) || this.isUsingDeclaration;
 	}
 
 	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren): void {
@@ -57,7 +59,7 @@ export default class VariableDeclarator extends NodeBase {
 			snippets: { _, getPropertyAccess }
 		} = options;
 		const { end, id, init, start } = this;
-		const renderId = id.included;
+		const renderId = id.included || this.isUsingDeclaration;
 		if (renderId) {
 			id.render(code, options);
 		} else {

src/ast/nodes/shared/VariableKinds.ts

@@ -1,2 +1,2 @@
-export type VariableDeclarationKind = 'var' | 'let' | 'const';
+export type VariableDeclarationKind = 'var' | 'let' | 'const' | 'using' | 'await using';
 export type VariableKind = VariableDeclarationKind | 'function' | 'class' | 'parameter' | 'other';

src/utils/convert-ast-strings.ts

@@ -58,5 +58,8 @@ export const FIXED_STRINGS = [
 	'||=',
 	'??=',
 	'pure',
-	'noSideEffects'
+	'noSideEffects',
+	'sourcemap',
+	'using',
+	'await using'
 ];

test/form/samples/support-using-keyword/_config.js

@@ -0,0 +1,4 @@
+module.exports = defineTest({
+	description: 'Support `using` keyword',
+	verifyAst: false
+});

test/form/samples/support-using-keyword/_expected.js

@@ -0,0 +1,22 @@
+const logClean = function () {
+	return {
+		[Symbol.dispose]() {
+			console.log('clean in sync');
+		},
+		[Symbol.asyncDispose]() {
+			console.log('clean in async');
+		}
+	};
+};
+
+async function foo() {
+	using a = logClean();
+	await using b = logClean();
+	for (using a of [logClean(), logClean()]) {
+	}
+
+	for (await using a of [logClean(), logClean()]) {
+	}
+}
+
+foo();

test/form/samples/support-using-keyword/main.js

@@ -0,0 +1,25 @@
+const logClean = function () {
+	return {
+		[Symbol.dispose]() {
+			console.log('clean in sync');
+		},
+		[Symbol.asyncDispose]() {
+			console.log('clean in async');
+		}
+	};
+};
+
+async function foo() {
+	using a = logClean();
+	const aa = a;
+
+	await using b = logClean();
+
+	for (using a of [logClean(), logClean()]) {
+	}
+
+	for (await using a of [logClean(), logClean()]) {
+	}
+}
+
+foo();