fix(rosetta): Rosetta does not support await (#3915)

Now it does.

---

By submitting this pull request, I confirm that my contribution is made under the terms of the [Apache 2.0 license].

[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

packages/jsii-rosetta/lib/languages/default.ts

@@ -117,6 +117,10 @@ export abstract class DefaultVisitor<C> implements AstHandler<C> {
     return this.regularCallExpression(node, context);
   }
 
+  public awaitExpression(node: ts.AwaitExpression, context: AstRenderer<C>): OTree {
+    return context.convert(node.expression);
+  }
+
   public regularCallExpression(node: ts.CallExpression, context: AstRenderer<C>): OTree {
     return new OTree([context.convert(node.expression), '(', this.argumentList(node.arguments, context), ')']);
   }

packages/jsii-rosetta/lib/languages/visualize.ts

@@ -90,6 +90,10 @@ export class VisualizeAstVisitor implements AstHandler<void> {
     return this.defaultNode('newExpression', node, context);
   }
 
+  public awaitExpression(node: ts.AwaitExpression, context: AstRenderer<void>): OTree {
+    return this.defaultNode('await', node, context);
+  }
+
   public propertyAssignment(node: ts.PropertyAssignment, context: AstRenderer<void>): OTree {
     return this.defaultNode('propertyAssignment', node, context);
   }

packages/jsii-rosetta/lib/renderer.ts

@@ -284,6 +284,9 @@ export class AstRenderer<C> {
     if (ts.isPropertyAccessExpression(tree)) {
       return visitor.propertyAccessExpression(tree, this);
     }
+    if (ts.isAwaitExpression(tree)) {
+      return visitor.awaitExpression(tree, this);
+    }
     if (ts.isCallExpression(tree)) {
       return visitor.callExpression(tree, this);
     }
@@ -471,6 +474,7 @@ export interface AstHandler<C> {
   binaryExpression(node: ts.BinaryExpression, context: AstRenderer<C>): OTree;
   ifStatement(node: ts.IfStatement, context: AstRenderer<C>): OTree;
   propertyAccessExpression(node: ts.PropertyAccessExpression, context: AstRenderer<C>): OTree;
+  awaitExpression(node: ts.AwaitExpression, context: AstRenderer<C>): OTree;
   callExpression(node: ts.CallExpression, context: AstRenderer<C>): OTree;
   expressionStatement(node: ts.ExpressionStatement, context: AstRenderer<C>): OTree;
   token<A extends ts.SyntaxKind>(node: ts.Token<A>, context: AstRenderer<C>): OTree;

packages/jsii-rosetta/test/translations/expressions/await.cs

@@ -0,0 +1 @@
+int x = Future();

packages/jsii-rosetta/test/translations/expressions/await.go

@@ -0,0 +1 @@
+x := future()

packages/jsii-rosetta/test/translations/expressions/await.java

@@ -0,0 +1 @@
+Number x = future();

packages/jsii-rosetta/test/translations/expressions/await.py

@@ -0,0 +1 @@
+x = future()

packages/jsii-rosetta/test/translations/expressions/await.ts

@@ -0,0 +1,7 @@
+/// !hide
+function future(): Promise<number> {
+  return Promise.resolve(5);
+}
+/// !show
+
+const x = await future();