rejigger strict directives transformer logic so they're included in the body before module formatters are ran - @jayphelps

lib/babel/transformation/helpers/use-strict.js

@@ -0,0 +1,21 @@
+"use strict";
+
+var t = require("../../types");
+
+exports.has = function (node) {
+  var first = node.body[0];
+  return t.isExpressionStatement(first) && t.isLiteral(first.expression, { value: "use strict" });
+};
+
+exports.wrap = function (node, callback) {
+  var useStrictNode;
+  if (exports.has(node)) {
+    useStrictNode = node.body.shift();
+  }
+
+  callback();
+
+  if (useStrictNode) {
+    node.body.unshift(useStrictNode);
+  }
+};

lib/babel/transformation/transformers/index.js

@@ -95,6 +95,7 @@ module.exports = {
   "spec.typeofSymbol":                     require("./spec/typeof-symbol"),
   "spec.undefinedToVoid":                  require("./spec/undefined-to-void"),
 
+  _useStrict:                              require("./internal/use-strict"),
   _moduleFormatter:                        require("./internal/module-formatter"),
 
   "es3.propertyLiterals":                  require("./es3/property-literals"),

lib/babel/transformation/transformers/internal/declarations.js

@@ -1,6 +1,7 @@
 "use strict";
 
-var t = require("../../../types");
+var useStrict = require("../../helpers/use-strict");
+var t         = require("../../../types");
 
 exports.secondPass = true;
 
@@ -8,26 +9,28 @@ exports.BlockStatement =
 exports.Program = function (node, parent, scope, file) {
   if (!node._declarations) return;
 
-  var kinds = {};
-  var kind;
+  useStrict.wrap(node, function () {
+    var kinds = {};
+    var kind;
 
-  for (var i in node._declarations) {
-    var declar = node._declarations[i];
+    for (var i in node._declarations) {
+      var declar = node._declarations[i];
 
-    kind = declar.kind || "var";
-    var declarNode = t.variableDeclarator(declar.id, declar.init);
+      kind = declar.kind || "var";
+      var declarNode = t.variableDeclarator(declar.id, declar.init);
 
-    if (declar.init) {
-      node.body.unshift(file.attachAuxiliaryComment(t.variableDeclaration(kind, [declarNode])));
-    } else {
-      kinds[kind] = kinds[kind] || [];
-      kinds[kind].push(declarNode);
+      if (declar.init) {
+        node.body.unshift(file.attachAuxiliaryComment(t.variableDeclaration(kind, [declarNode])));
+      } else {
+        kinds[kind] = kinds[kind] || [];
+        kinds[kind].push(declarNode);
+      }
     }
-  }
 
-  for (kind in kinds) {
-    node.body.unshift(file.attachAuxiliaryComment(t.variableDeclaration(kind, kinds[kind])));
-  }
+    for (kind in kinds) {
+      node.body.unshift(file.attachAuxiliaryComment(t.variableDeclaration(kind, kinds[kind])));
+    }
 
-  node._declarations = null;
+    node._declarations = null;
+  });
 };

lib/babel/transformation/transformers/internal/module-formatter.js

@@ -1,9 +1,13 @@
 "use strict";
 
+var useStrict = require("../../helpers/use-strict");
+
 exports.Program = function (program, parent, scope, file) {
   if (!file.transformers["es6.modules"].canRun()) return;
 
-  program.body = file.dynamicImports.concat(program.body);
+  useStrict.wrap(program, function () {
+    program.body = file.dynamicImports.concat(program.body);
+  });
 
   if (file.moduleFormatter.transform) {
     file.moduleFormatter.transform(program);

lib/babel/transformation/transformers/internal/use-strict.js

@@ -0,0 +1,9 @@
+"use strict";
+
+var t = require("../../../types");
+
+exports.Program = function (program, parent, scope, file) {
+  if (file.transformers.useStrict.canRun()) {
+    program.body.unshift(t.expressionStatement(t.literal("use strict")));
+  }
+};

lib/babel/transformation/transformers/other/use-strict.js

@@ -10,10 +10,6 @@ exports.Program = function (program) {
   }
 };
 
-exports.post = function (file) {
-  file.ast.program.body.unshift(t.expressionStatement(t.literal("use strict")));
-};
-
 exports.FunctionDeclaration =
 exports.FunctionExpression = function () {
   this.skip();