Allow multiple named exports of the same symbol.

Since it's impossible to avoid aliases in the rewriting of this case, just make the second export an alias of the first, as if the user had written: exports.firstName = localName; exports.secondName = exports.firstName; ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=146963601
google · Feb 9, 2017 · db7a7b4 · db7a7b4
1 parent c76aeab
commit db7a7b4
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Showing 2 changed files with 28 additions and 9 deletions.
diff --git a/src/com/google/javascript/jscomp/ClosureRewriteModule.java b/src/com/google/javascript/jscomp/ClosureRewriteModule.java
@@ -246,8 +246,9 @@ String getExportPostfix() {
       return "." + exportName;
     }
 
-    boolean hasInlinableName() {
+    boolean hasInlinableName(Set<Var> exportedNames) {
       if (nameDecl == null
+          || exportedNames.contains(nameDecl)
           || !INLINABLE_NAME_PARENTS.contains(nameDecl.getParentNode().getToken())) {
         return false;
       }
@@ -261,10 +262,7 @@ boolean hasInlinableName() {
     }
 
     String getLocalName() {
-      if (hasInlinableName()) {
-        return nameDecl.getName();
-      }
-      return null;
+      return nameDecl.getName();
     }
   }
 
@@ -868,7 +866,8 @@ private void maybeRecordExportDeclaration(NodeTraversal t, Node n) {
         Node rhs = key.hasChildren() ? key.getFirstChild() : key;
         ExportDefinition namedExport = ExportDefinition.newNamedExport(t, exportName, rhs);
         currentScript.namedExports.add(exportName);
-        if (currentScript.declareLegacyNamespace || !namedExport.hasInlinableName()) {
+        if (currentScript.declareLegacyNamespace
+            || !namedExport.hasInlinableName(currentScript.exportsToInline.keySet())) {
           areAllExportsInlinable = false;
         } else {
           inlinableExports.add(namedExport);
@@ -888,7 +887,8 @@ private void maybeRecordExportDeclaration(NodeTraversal t, Node n) {
     currentScript.defaultExportRhs = exportRhs;
     currentScript.willCreateExportsObject = true;
     ExportDefinition defaultExport = ExportDefinition.newDefaultExport(t, exportRhs);
-    if (!currentScript.declareLegacyNamespace && defaultExport.hasInlinableName()) {
+    if (!currentScript.declareLegacyNamespace
+        && defaultExport.hasInlinableName(currentScript.exportsToInline.keySet())) {
       String localName = defaultExport.getLocalName();
       currentScript.defaultExportLocalName = localName;
       recordExportToInline(defaultExport);
@@ -1127,7 +1127,7 @@ private void recordExportsPropertyAssignment(NodeTraversal t, Node getpropNode)
       ExportDefinition namedExport = ExportDefinition.newNamedExport(t, exportName, exportRhs);
       if (!currentScript.declareLegacyNamespace
           && currentScript.defaultExportRhs == null
-          && namedExport.hasInlinableName()) {
+          && namedExport.hasInlinableName(currentScript.exportsToInline.keySet())) {
         recordExportToInline(namedExport);
         parent.getParent().detach();
       }
@@ -1461,7 +1461,11 @@ private void markConstAndCopyJsDoc(Node from, Node target, Node value) {
   }
 
   private void recordExportToInline(ExportDefinition exportDefinition) {
-    currentScript.exportsToInline.put(exportDefinition.nameDecl, exportDefinition);
+    Preconditions.checkState(
+        exportDefinition.hasInlinableName(currentScript.exportsToInline.keySet()));
+    Preconditions.checkState(
+        null == currentScript.exportsToInline.put(exportDefinition.nameDecl, exportDefinition),
+        "Already found a mapping for inlining export: %s", exportDefinition.nameDecl);
     String localName = exportDefinition.getLocalName();
     String fullExportedName =
         currentScript.getBinaryNamespace() + exportDefinition.getExportPostfix();

diff --git a/test/com/google/javascript/jscomp/ClosureRewriteModuleTest.java b/test/com/google/javascript/jscomp/ClosureRewriteModuleTest.java
@@ -2085,6 +2085,21 @@ public void testRewriteGoogModuleAliasesWithPrototypeGets2() {
         });
   }
 
+  public void testMultiplyExportedSymbolDoesntCrash() {
+    testEs6(
+        LINE_JOINER.join(
+            "goog.module('mod');",
+            "",
+            "class Foo {}",
+            "",
+            "exports.name1 = Foo;",
+            "exports.name2 = Foo;"),
+        LINE_JOINER.join(
+            "/** @const */ var module$exports$mod = {};",
+            "module$exports$mod.name1 = class {};",
+            "/** @const */ module$exports$mod.name2 = module$exports$mod.name1;"));
+  }
+
   public void testIjsFileInExterns() {
     allowExternsChanges(true);
     test(