Unwrap promise wrapping in IIFEs

async-to-promises.ts

@@ -3340,6 +3340,31 @@ export default function({ types, template, traverse, transformFromAst, version }
 		}
 	}
 
+	const unwrapReturnPromiseVisitor: Visitor = {
+		ReturnStatement(path) {
+			const argument = path.get("argument");
+			if (argument.isCallExpression()) {
+				switch (promiseCallExpressionType(argument.node)) {
+					case "all":
+					case "race":
+					case "resolve":
+						switch (argument.node.arguments.length) {
+							case 0:
+								path.replaceWith(types.returnStatement());
+								break;
+							case 1:
+								const arg0 = argument.node.arguments[0];
+								if (types.isExpression(arg0)) {
+									path.replaceWith(types.returnStatement(arg0));
+								}
+								break;
+						}
+						break;
+				}
+			}
+		}
+	};
+
 	// Main babel plugin implementation and top level visitor
 	return {
 		manipulateOptions(options: any, parserOptions: { plugins: string[] }) {
@@ -3422,6 +3447,9 @@ export default function({ types, template, traverse, transformFromAst, version }
 						if (inlineHelpers && !pathsReturnOrThrowCurrentNodes(bodyPath).all && !skipReturn) {
 							path.node.body.body.push(types.returnStatement(types.callExpression(promiseResolve(), [])));
 						}
+						if (skipReturn) {
+							path.traverse(unwrapReturnPromiseVisitor);
+						}
 						if (canThrow) {
 							if (inlineHelpers) {
 								if (skipReturn && parentPath.isCallExpression() && parentPath.node.arguments.length === 0 && !pathsReturn(bodyPath).any) {

tests/iife simplification with returns/hoisted.js

@@ -0,0 +1 @@
+_async(function(){console.log('foo');if(foo){return console.log(foo);}})();

tests/iife simplification with returns/inlined.js

@@ -0,0 +1 @@
+(function(){try{console.log('foo');if(foo){return console.log(foo);}}catch(e){Promise.reject(e);}})();

tests/iife simplification with returns/input.js

@@ -0,0 +1,6 @@
+(async function() {
+	console.log('foo');
+	if (foo) {
+		return console.log(foo);
+	}
+})();

tests/iife simplification with returns/options.json

@@ -0,0 +1,3 @@
+{
+	"module": true
+}

tests/iife simplification with returns/output.js

@@ -0,0 +1 @@
+_async(()=>{console.log('foo');if(foo){return console.log(foo);}})();