fix(es/compat): Fix async generator (#8881)

**Related issue:** - Closes #8805
swc-project · Apr 23, 2024 · 063eabd · 063eabd
1 parent 16a3885
commit 063eabd
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Showing 5 changed files with 70 additions and 17 deletions.
diff --git a/crates/swc/tests/tsc-references/emitter.forAwait(target=es2015).1.normal.js b/crates/swc/tests/tsc-references/emitter.forAwait(target=es2015).1.normal.js
@@ -89,7 +89,7 @@ function _f3() {
             } finally{
                 try {
                     if (_iteratorAbruptCompletion && _iterator.return != null) {
-                        yield _iterator.return();
+                        yield _await_async_generator(_iterator.return());
                     }
                 } finally{
                     if (_didIteratorError) {
@@ -124,7 +124,7 @@ function _f4() {
             } finally{
                 try {
                     if (_iteratorAbruptCompletion && _iterator.return != null) {
-                        yield _iterator.return();
+                        yield _await_async_generator(_iterator.return());
                     }
                 } finally{
                     if (_didIteratorError) {
@@ -197,7 +197,7 @@ function _f6() {
             } finally{
                 try {
                     if (_iteratorAbruptCompletion && _iterator.return != null) {
-                        yield _iterator.return();
+                        yield _await_async_generator(_iterator.return());
                     }
                 } finally{
                     if (_didIteratorError) {
@@ -234,7 +234,7 @@ function _f7() {
                 } finally{
                     try {
                         if (_iteratorAbruptCompletion && _iterator.return != null) {
-                            yield _iterator.return();
+                            yield _await_async_generator(_iterator.return());
                         }
                     } finally{
                         if (_didIteratorError) {

diff --git a/crates/swc/tests/tsc-references/emitter.forAwait(target=es5).1.normal.js b/crates/swc/tests/tsc-references/emitter.forAwait(target=es5).1.normal.js
@@ -266,7 +266,7 @@ function _f3() {
                     ];
                     return [
                         4,
-                        _iterator.return()
+                        _await_async_generator(_iterator.return())
                     ];
                 case 8:
                     _state.sent();
@@ -366,7 +366,7 @@ function _f4() {
                     ];
                     return [
                         4,
-                        _iterator.return()
+                        _await_async_generator(_iterator.return())
                     ];
                 case 8:
                     _state.sent();
@@ -569,7 +569,7 @@ function _f6() {
                     ];
                     return [
                         4,
-                        _iterator.return()
+                        _await_async_generator(_iterator.return())
                     ];
                 case 8:
                     _state.sent();
@@ -670,7 +670,7 @@ function _f7() {
                     ];
                     return [
                         4,
-                        _iterator.return()
+                        _await_async_generator(_iterator.return())
                     ];
                 case 8:
                     _state.sent();

diff --git a/crates/swc_ecma_compat_es2017/src/async_to_generator.rs b/crates/swc_ecma_compat_es2017/src/async_to_generator.rs
@@ -790,21 +790,34 @@ fn handle_await_for(stmt: &mut Stmt, is_async_generator: bool) {
             alt: None,
         });
 
+        let iterator_return = Box::new(Expr::Call(CallExpr {
+            span: DUMMY_SP,
+            callee: iterator
+                .clone()
+                .make_member(quote_ident!("return"))
+                .as_callee(),
+            args: vec![],
+            type_args: Default::default(),
+        }));
+
         // yield _iterator.return();
+        // or
+        // yield _awaitAsyncGenerator(_iterator.return());
         let yield_stmt = Stmt::Expr(ExprStmt {
             span: DUMMY_SP,
             expr: Box::new(Expr::Yield(YieldExpr {
                 span: DUMMY_SP,
                 delegate: false,
-                arg: Some(Box::new(Expr::Call(CallExpr {
-                    span: DUMMY_SP,
-                    callee: iterator
-                        .clone()
-                        .make_member(quote_ident!("return"))
-                        .as_callee(),
-                    args: Default::default(),
-                    type_args: Default::default(),
-                }))),
+                arg: Some(if is_async_generator {
+                    Box::new(Expr::Call(CallExpr {
+                        span: DUMMY_SP,
+                        callee: helper!(await_async_generator),
+                        args: vec![iterator_return.as_arg()],
+                        type_args: Default::default(),
+                    }))
+                } else {
+                    iterator_return
+                }),
             })),
         });
 

diff --git a/crates/swc_ecma_transforms_compat/tests/async-to-generator/issue-8805/1/exec.js b/crates/swc_ecma_transforms_compat/tests/async-to-generator/issue-8805/1/exec.js
@@ -0,0 +1,20 @@
+async function* foo() {
+    yield 1
+}
+
+async function* bar(inputs, returnValues) {
+    for await (const input of inputs) {
+        if (!returnValues) {
+            return
+        }
+        yield input
+    }
+}
+
+async function run() {
+    for await (const number of bar(foo(), true)) {
+        console.log(number)
+    }
+}
+
+run()
diff --git a/crates/swc_ecma_transforms_compat/tests/async-to-generator/issue-8805/2/exec.js b/crates/swc_ecma_transforms_compat/tests/async-to-generator/issue-8805/2/exec.js
@@ -0,0 +1,20 @@
+async function* foo() {
+    yield 1
+}
+
+async function* bar(inputs, returnValues) {
+    for await (const input of inputs) {
+        if (!returnValues) {
+            return
+        }
+        yield input
+    }
+}
+
+async function run() {
+    for await (const value of bar(foo(), false)) {
+        console.log(value)
+    }
+}
+
+run()