Pass modified exports instead of variables

Author: zodern

lib/assignment-visitor.js

@@ -89,24 +89,33 @@ function assignmentHelper(visitor, path, childName) {
     return !scope || scope.find_owner(name).parent === null;
   }
 
-  // Wrap assignments to exported identifiers with `module.runSetters`.
+  let modifiedExports = [];
+  
+  // Identify which exports if any are modified by the assignment.
   for (let i = 0; i < nameCount; ++i) {
     let name = assignedNames[i];
     if (
-      visitor.exportedLocalNames[name] === true &&
+      visitor.exportedLocalNames[name] &&
       inModuleScope(name)
     ) {
-      wrap(visitor, path, name);
-      break;
+      modifiedExports.push(...visitor.exportedLocalNames[name]);
     }
   }
+  
+  // Wrap assignments to exported identifiers with `module.runSetters`.
+  if (modifiedExports.length > 0) {
+    wrap(visitor, path, modifiedExports);
+  }
 }
 
-function wrap(visitor, path, name) {
+function wrap(visitor, path, names) {
   const value = path.getValue();
 
   if (visitor.magicString !== null) {
-    let end = name ? `,"${name}")` : ')';
+    let end = ')';
+    if (names) {
+      end = `,[${names.map(n => `"${n}"`).join(',')}])`;
+    }
 
     visitor.magicString.prependRight(
       value.start,
@@ -115,10 +124,14 @@ function wrap(visitor, path, name) {
   }
 
   if (visitor.modifyAST) {
-    let args = name ? [value, {
-      type: "StringLiteral",
-      value: name
-    }] : [value];
+    let args = [value];
+    if (names) {
+      let array = {
+        type: "ArrayExpression",
+        elements: names.map(n => ({ type: "StringLiteral", value: n }))
+      };
+      args.push(array);
+    }
 
     path.replace({
       type: "CallExpression",

lib/import-export-visitor.js

@@ -457,12 +457,10 @@ function addExportedLocalNames(visitor, specifierMap) {
     const localCount = locals.length;
 
     for (let j = 0; j < localCount; ++j) {
-      // It's tempting to record the exported name as the value here,
-      // instead of true, but there can be more than one exported name
-      // per local variable, and we don't actually use the exported
-      // name(s) in the assignmentVisitor, so it's not worth the added
-      // complexity of tracking unused information.
-      exportedLocalNames[locals[j]] = true;
+      if (exportedLocalNames[locals[j]] === undefined) {
+        exportedLocalNames[locals[j]] = [];
+      }
+      exportedLocalNames[locals[j]].push(exported);
     }
   }
 }

lib/runtime/index.js

@@ -118,10 +118,6 @@ function moduleExportAs(name) {
 // might happen more than once per module, in case of dependency cycles,
 // so we want Module.prototype.runSetters to run each time.
 function runSetters(valueToPassThrough, names) {
-  if (typeof names === 'string') {
-    names = [names];
-  }
-
   Entry.getOrCreate(this.id, this).runSetters(names, true);
 
   // Assignments to exported local variables get wrapped with calls to

test/output/declarations-basic/expected.js

@@ -7,4 +7,4 @@ function d() {
   return b;
 };
 
-module.runSetters(c = "c","c");
+module.runSetters(c = "c",["c"]);

test/output/live/expected.js

@@ -1,9 +1,9 @@
 "use strict";module.export({value:()=>value,reset:()=>reset,add:()=>add});var value = reset();
 
 function reset() {
-  return module.runSetters(value = 0,"value");
+  return module.runSetters(value = 0,["value"]);
 }
 
 function add(x) {
-  module.runSetters(value += x,"value");
+  module.runSetters(value += x,["value"]);
 };

test/output/reassign-multiple/actual.js

@@ -0,0 +1,7 @@
+export let a = 5;
+export let b = 6;
+export { a as x };
+
+export function switchValues() {
+  [a, b] = [b, a];
+}

test/output/reassign-multiple/expected.js

@@ -0,0 +1,7 @@
+"use strict";module.export({a:()=>a,b:()=>b,x:()=>a,switchValues:()=>switchValues});let a = 5;
+let b = 6;
+
+
+function switchValues() {
+  module.runSetters([a, b] = [b, a],["a","x","b"]);
+}