Properly preserve import ordering with AMD format. (#5474)

Previously, all "bare imports" (e.g. `import './foo';`) were moved to the
end of the array of sources. I presume this was done to remove needless
variables in the callback signature.

Unfortunately, doing this actually changes the intent of the program.
Modules should be evaluated in the order that they were in the source.

In the case of a bare import, it is quite possible that the bare import
has side effects that a later required module should see. With the current
implementation the later imported modules are evaluated before that "side
effecty" module has been evaluated.

Obviously, it is better to avoid these sorts of side effect ridden modules
but even still you could imagine a similar issue with cycles.

This change ensures that module source order is preserved in the AMD
dependencies list, and avoids making needless variables as much as possible.

packages/babel-plugin-transform-es2015-modules-amd/src/index.js

@@ -1,3 +1,4 @@
+import { basename, extname } from "path";
 import template from "babel-template";
 import transformCommonjs from "babel-plugin-transform-es2015-modules-commonjs";
 
@@ -26,6 +27,28 @@ export default function ({ types: t }) {
     return true;
   }
 
+  function buildParamsAndSource(sourcesFound) {
+    const params = [];
+    const sources = [];
+
+    let hasSeenNonBareRequire = false;
+    for (let i = sourcesFound.length - 1; i > -1; i--) {
+      const source = sourcesFound[i];
+
+      sources.unshift(source[1]);
+
+      // bare import at end, no need for param
+      if (!hasSeenNonBareRequire && source[2] === true) {
+        continue;
+      }
+
+      hasSeenNonBareRequire = true;
+      params.unshift(source[0]);
+    }
+
+    return [ params, sources];
+  }
+
   const amdVisitor = {
     ReferencedIdentifier({ node, scope }) {
       if (node.name === "exports" && !scope.getBinding("exports")) {
@@ -39,7 +62,9 @@ export default function ({ types: t }) {
 
     CallExpression(path) {
       if (!isValidRequireCall(path)) return;
-      this.bareSources.push(path.node.arguments[0]);
+      const source = path.node.arguments[0];
+      const ref = path.scope.generateUidIdentifier(basename(source.value, extname(source.value)));
+      this.sources.push([ref, source, true]);
       path.remove();
     },
 
@@ -66,9 +91,6 @@ export default function ({ types: t }) {
       this.sources = [];
       this.sourceNames = Object.create(null);
 
-      // bare sources
-      this.bareSources = [];
-
       this.hasExports = false;
       this.hasModule = false;
     },
@@ -81,12 +103,7 @@ export default function ({ types: t }) {
 
           path.traverse(amdVisitor, this);
 
-          const params = this.sources.map((source) => source[0]);
-          let sources = this.sources.map((source) => source[1]);
-
-          sources = sources.concat(this.bareSources.filter((str) => {
-            return !this.sourceNames[str.value];
-          }));
+          const [params, sources ] = buildParamsAndSource(this.sources);
 
           let moduleName = this.getModuleName();
           if (moduleName) moduleName = t.stringLiteral(moduleName);

packages/babel-plugin-transform-es2015-modules-amd/test/fixtures/amd/import-order/actual.js

@@ -0,0 +1,4 @@
+import './foo';
+import bar from './bar';
+import './derp';
+import { qux } from './qux';

packages/babel-plugin-transform-es2015-modules-amd/test/fixtures/amd/import-order/expected.js

@@ -0,0 +1,5 @@
+define(['./foo', './bar', './derp', './qux'], function (_foo, _bar, _derp, _qux) {
+  'use strict';
+
+  var _bar2 = babelHelpers.interopRequireDefault(_bar);
+});

packages/babel-plugin-transform-es2015-modules-commonjs/test/fixtures/interop/imports-ordering/actual.js

@@ -0,0 +1,4 @@
+import './foo';
+import bar from './bar';
+import './derp';
+import { qux } from './qux';

packages/babel-plugin-transform-es2015-modules-commonjs/test/fixtures/interop/imports-ordering/expected.js

@@ -0,0 +1,11 @@
+'use strict';
+
+require('./foo');
+
+var _bar = require('./bar');
+
+var _bar2 = babelHelpers.interopRequireDefault(_bar);
+
+require('./derp');
+
+var _qux = require('./qux');