Allow flow-declared variables when inlining

Summary: The logic of the `inline` babel transform regarded identifiers as global if no binding exists for them. We extend that logic to also accept flow-declared variables.

Reviewed By: arcanis

Differential Revision: D4737620

fbshipit-source-id: e71cfdf77c7b7751265cfa4412430b4f29e9e853

packages/metro-bundler/package.json

@@ -1,5 +1,5 @@
 {
-  "version": "0.5.0",
+  "version": "0.5.1",
   "name": "react-native-packager",
   "description": "Build native apps with React!",
   "repository": {

packages/metro-bundler/src/JSTransformer/worker/__tests__/inline-test.js

@@ -306,4 +306,32 @@ describe('inline constants', () => {
     expect(toString(ast)).toEqual(
       normalize(code.replace(/require\([^)]+\)\.Platform\.OS/, '"android"')));
   });
+
+  it('works with flow-declared variables', () => {
+    const stripFlow = require('babel-plugin-transform-flow-strip-types');
+    const code = `declare var __DEV__;
+      const a: boolean = __DEV__;`;
+
+    const transformed = transform(
+      code,
+      {...babelOptions, plugins: [stripFlow, [inline.plugin, {dev: false}]]},
+    ).code;
+
+    expect(transformed).toEqual('const a=false;');
+  });
+
+  it('works with flow-declared variables in wrapped modules', () => {
+    const stripFlow = require('babel-plugin-transform-flow-strip-types');
+    const code = `__d(() => {
+      declare var __DEV__;
+      const a: boolean = __DEV__;
+    });`;
+
+    const transformed = transform(
+      code,
+      {...babelOptions, plugins: [stripFlow, [inline.plugin, {dev: true}]]},
+    ).code;
+
+    expect(transformed).toEqual('__d(()=>{const a=true;});');
+  });
 });

packages/metro-bundler/src/JSTransformer/worker/inline.js

@@ -34,6 +34,12 @@ const importMap = new Map([['ReactNative', 'react-native']]);
 
 const isGlobal = binding => !binding;
 
+const isFlowDeclared = binding =>
+  t.isDeclareVariable(binding.path);
+
+const isGlobalOrFlowDeclared = binding =>
+  isGlobal(binding) || isFlowDeclared(binding);
+
 const isToplevelBinding = (binding, isWrappedModule) =>
   isGlobal(binding) ||
   !binding.scope.parent ||
@@ -93,7 +99,7 @@ const isReactPlatformSelect = (node, scope, isWrappedModule) =>
 
 const isDev = (node, parent, scope) =>
   t.isIdentifier(node, dev) &&
-  isGlobal(scope.getBinding(dev.name)) &&
+  isGlobalOrFlowDeclared(scope.getBinding(dev.name)) &&
   !(t.isMemberExpression(parent));
 
 function findProperty(objectExpression, key, fallback) {