Parse async do expressions (#13043)

* parse async do expressions

* add test cases

* update test fixtures

* chore: add syntax-async-do-expressions

* generater support

* fix: do not transform async do expressions

* chore: add asyncDoExpressions to missing plugin helpers

* update ast types

* add more test cases

* throw when asyncDoExpressions is enabled but not doExpressions

* avoid add parentheses for async do expressions

* address review comments

* chore: update parser typings

packages/babel-parser/src/parser/expression.js

@@ -1033,6 +1033,8 @@ export default class ExpressionParser extends LValParser {
             );
           } else if (this.match(tt.name)) {
             return this.parseAsyncArrowUnaryFunction(id);
+          } else if (this.match(tt._do)) {
+            return this.parseDo(true);
           }
         }
 
@@ -1049,7 +1051,7 @@ export default class ExpressionParser extends LValParser {
       }
 
       case tt._do: {
-        return this.parseDo();
+        return this.parseDo(false);
       }
 
       case tt.regexp: {
@@ -1231,13 +1233,27 @@ export default class ExpressionParser extends LValParser {
   }
 
   // https://github.com/tc39/proposal-do-expressions
-  parseDo(): N.DoExpression {
+  // https://github.com/tc39/proposal-async-do-expressions
+  parseDo(isAsync: boolean): N.DoExpression {
     this.expectPlugin("doExpressions");
+    if (isAsync) {
+      this.expectPlugin("asyncDoExpressions");
+    }
     const node = this.startNode();
+    node.async = isAsync;
     this.next(); // eat `do`
     const oldLabels = this.state.labels;
     this.state.labels = [];
-    node.body = this.parseBlock();
+    if (isAsync) {
+      // AsyncDoExpression :
+      // async [no LineTerminator here] do Block[~Yield, +Await, ~Return]
+      this.prodParam.enter(PARAM_AWAIT);
+      node.body = this.parseBlock();
+      this.prodParam.exit();
+    } else {
+      node.body = this.parseBlock();
+    }
+
     this.state.labels = oldLabels;
     return this.finishNode(node, "DoExpression");
   }

packages/babel-parser/src/plugin-utils.js

@@ -117,6 +117,18 @@ export function validatePlugins(plugins: PluginList) {
         RECORD_AND_TUPLE_SYNTAX_TYPES.map(p => `'${p}'`).join(", "),
     );
   }
+
+  if (
+    hasPlugin(plugins, "asyncDoExpressions") &&
+    !hasPlugin(plugins, "doExpressions")
+  ) {
+    const error = new Error(
+      "'asyncDoExpressions' requires 'doExpressions', please add 'doExpressions' to parser plugins.",
+    );
+    // $FlowIgnore
+    error.missingPlugins = "doExpressions"; // so @babel/core can provide better error message
+    throw error;
+  }
 }
 
 // These plugins are defined using a mixin which extends the parser class.

packages/babel-parser/src/types.js

@@ -402,6 +402,7 @@ export type ArrayExpression = NodeBase & {
 export type DoExpression = NodeBase & {
   type: "DoExpression",
   body: ?BlockStatement,
+  async: boolean,
 };
 
 export type TupleExpression = NodeBase & {