fix: type inference on forwardRef components (#392)

src/__tests__/__snapshots__/main-test.js.snap

@@ -982,7 +982,11 @@ Object {
   "props": Object {
     "color": Object {
       "description": "",
-      "required": true,
+      "flowType": Object {
+        "name": "string",
+        "nullable": true,
+      },
+      "required": false,
       "type": Object {
         "name": "string",
       },
@@ -1421,3 +1425,24 @@ Object {
   },
 }
 `;
+
+exports[`main fixtures processes component "component_28.tsx" without errors 1`] = `
+Object {
+  "description": "Example component description",
+  "displayName": "ABC",
+  "methods": Array [],
+  "props": Object {
+    "foo": Object {
+      "defaultValue": Object {
+        "computed": false,
+        "value": "true",
+      },
+      "description": "Example prop description",
+      "required": false,
+      "tsType": Object {
+        "name": "boolean",
+      },
+    },
+  },
+}
+`;

src/__tests__/fixtures/component_28.tsx

@@ -0,0 +1,27 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+
+import React from 'react';
+
+interface Props {
+  /**
+   * Example prop description
+   */
+  foo: boolean;
+}
+
+/**
+ * Example component description
+ */
+const Component = React.forwardRef(({ foo = true }: Props, ref: any) => {
+  return <div />;
+})
+
+Component.displayName = 'ABC';
+
+export default Component;

src/__tests__/main-test.js

@@ -8,7 +8,7 @@
 
 import fs from 'fs';
 import path from 'path';
-import { parse, handlers } from '../main';
+import { handlers, parse } from '../main';
 import { ERROR_MISSING_DEFINITION } from '../parse';
 
 describe('main', () => {
@@ -45,7 +45,7 @@ describe('main', () => {
 
   describe('React.createClass', () => {
     test(`
-      var React = require("React");
+      var React = require("react");
       var PropTypes = React.PropTypes;
 
       var defaultProps = {
@@ -74,7 +74,7 @@ describe('main', () => {
 
   describe('Class definition', () => {
     test(`
-      const React = require("React");
+      const React = require("react");
       const PropTypes = React.PropTypes;
 
       const defaultProps = {
@@ -101,7 +101,7 @@ describe('main', () => {
 
   describe('Stateless Component definition: ArrowFunctionExpression', () => {
     test(`
-      import React, {PropTypes} from "React";
+      import React, {PropTypes} from "react";
 
       const defaultProps = {
         foo: true,
@@ -127,7 +127,7 @@ describe('main', () => {
 
   describe('Stateless Component definition: FunctionDeclaration', () => {
     test(`
-      import React, {PropTypes} from "React";
+      import React, {PropTypes} from "react";
 
       const defaultProps = {
         foo: true,
@@ -156,7 +156,7 @@ describe('main', () => {
 
   describe('Stateless Component definition: FunctionExpression', () => {
     test(`
-      import React, {PropTypes} from "React";
+      import React, {PropTypes} from "react";
 
       const defaultProps = {
         foo: true,
@@ -186,7 +186,7 @@ describe('main', () => {
   describe('Stateless Component definition', () => {
     it('is not so greedy', () => {
       const source = `
-        import React, {PropTypes} from "React";
+        import React, {PropTypes} from "react";
 
         /**
         * Example component description

src/handlers/flowTypeHandler.js

@@ -8,17 +8,17 @@
  */
 
 import types from 'ast-types';
+import type Documentation from '../Documentation';
+import { unwrapUtilityType } from '../utils/flowUtilityTypes';
 import getFlowType from '../utils/getFlowType';
-import getTSType from '../utils/getTSType';
-import getPropertyName from '../utils/getPropertyName';
 import getFlowTypeFromReactComponent, {
   applyToFlowTypeProperties,
 } from '../utils/getFlowTypeFromReactComponent';
+import getPropertyName from '../utils/getPropertyName';
+import getTSType from '../utils/getTSType';
+import { type TypeParameters } from '../utils/getTypeParameters';
 import resolveToValue from '../utils/resolveToValue';
 import setPropDescription from '../utils/setPropDescription';
-import { unwrapUtilityType } from '../utils/flowUtilityTypes';
-import { type TypeParameters } from '../utils/getTypeParameters';
-import type Documentation from '../Documentation';
 
 const { namedTypes: t } = types;
 

src/utils/getFlowTypeFromReactComponent.js

@@ -8,22 +8,30 @@
  */
 
 import type Documentation from '../Documentation';
-import getTypeAnnotation from '../utils/getTypeAnnotation';
-import getMemberValuePath from '../utils/getMemberValuePath';
-import isReactComponentClass from '../utils/isReactComponentClass';
-import isStatelessComponent from '../utils/isStatelessComponent';
-import resolveGenericTypeAnnotation from '../utils/resolveGenericTypeAnnotation';
-import getTypeParameters, {
-  type TypeParameters,
-} from '../utils/getTypeParameters';
+import getMemberValuePath from './getMemberValuePath';
+import getTypeAnnotation from './getTypeAnnotation';
+import getTypeParameters, { type TypeParameters } from './getTypeParameters';
+import isReactComponentClass from './isReactComponentClass';
+import isReactForwardRefCall from './isReactForwardRefCall';
+import resolveGenericTypeAnnotation from './resolveGenericTypeAnnotation';
+import resolveToValue from './resolveToValue';
+
+function getStatelessPropsPath(componentDefinition): NodePath {
+  const value = resolveToValue(componentDefinition);
+  if (isReactForwardRefCall(value)) {
+    const inner = value.get('arguments', 0);
+    return inner.get('params', 0);
+  }
+  return value.get('params', 0);
+}
 
 /**
  * Given an React component (stateless or class) tries to find the
  * flow type for the props. If not found or not one of the supported
  * component types returns null.
  */
 export default (path: NodePath): ?NodePath => {
-  let typePath: ?NodePath;
+  let typePath: ?NodePath = null;
 
   if (isReactComponentClass(path)) {
     const superTypes = path.get('superTypeParameters');
@@ -43,10 +51,14 @@ export default (path: NodePath): ?NodePath => {
 
       typePath = getTypeAnnotation(propsMemberPath.parentPath);
     }
-  } else if (isStatelessComponent(path)) {
-    const param = path.get('params').get(0);
 
-    typePath = getTypeAnnotation(param);
+    return typePath;
+  }
+
+  const propsParam = getStatelessPropsPath(path);
+
+  if (propsParam) {
+    typePath = getTypeAnnotation(propsParam);
   }
 
   return typePath;