feat: Support async functions

Author: devongovett

__tests__/__snapshots__/test.js.snap

@@ -9823,6 +9823,7 @@ It takes a ",
     "todos": Array [],
   },
   Object {
+    "async": true,
     "augments": Array [],
     "context": Object {
       "loc": Object {

__tests__/lib/infer/kind.js

@@ -82,13 +82,12 @@ test('inferKind', function() {
     ).kind
   ).toBe('function');
 
-  expect(
-    inferKind(
-      toComment(
-        '/** Export default function */' + 'export default function foo() {}'
-      )
-    ).kind
-  ).toBe('function');
+  const asyncFunction = inferKind(
+    toComment('/** Async function */' + 'async function foo() {}')
+  );
+
+  expect(asyncFunction.kind).toBe('function');
+  expect(asyncFunction.async).toBe(true);
 
   expect(
     inferKind(toComment('class Foo { /** set b */ set b(v) { } }')).kind
@@ -106,6 +105,12 @@ test('inferKind', function() {
     'function'
   );
 
+  const asyncMethod = inferKind(
+    toComment('class Foo { /** b */ async b(v) { } }')
+  );
+  expect(asyncMethod.kind).toBe('function');
+  expect(asyncMethod.async).toBe(true);
+
   expect(
     inferKind(
       toComment(function() {

__tests__/lib/parse.js

@@ -72,6 +72,14 @@ test('parse - @arg', function() {});
 
 test('parse - @argument', function() {});
 
+test('parse - @async', function() {
+  expect(
+    evaluate(function() {
+      /** @async */
+    })[0].async
+  ).toBe(true);
+});
+
 test('parse - @augments', function() {
   expect(
     evaluate(function() {

src/infer/kind.js

@@ -25,6 +25,9 @@ function inferKind(comment) {
         comment.kind = 'class';
       } else {
         comment.kind = 'function';
+        if (node.async) {
+          comment.async = true;
+        }
       }
     } else if (t.isTypeAlias(node)) {
       comment.kind = 'typedef';

src/parse.js

@@ -23,6 +23,7 @@ const flatteners = {
   alias: flattenName,
   arg: synonym('param'),
   argument: synonym('param'),
+  async: flattenBoolean,
   /**
    * Parse tag
    * @private