Back off from inlining type aliases when the aliased name is shadowed…

… by a local var. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=258461498
google · Jul 17, 2019 · 3cc33fe · 3cc33fe
1 parent a96aaaf
commit 3cc33fe
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Showing 2 changed files with 49 additions and 5 deletions.
diff --git a/src/com/google/javascript/jscomp/InlineAliases.java b/src/com/google/javascript/jscomp/InlineAliases.java
@@ -16,6 +16,7 @@
 
 package com.google.javascript.jscomp;
 
+import com.google.common.base.Preconditions;
 import com.google.javascript.jscomp.NodeTraversal.ExternsSkippingCallback;
 import com.google.javascript.rhino.JSDocInfo;
 import com.google.javascript.rhino.JSDocInfo.Visibility;
@@ -132,19 +133,21 @@ public void visit(NodeTraversal t, Node n, Node parent) {
         case NAME:
         case GETPROP:
           if (n.isQualifiedName() && aliases.containsKey(n.getQualifiedName())) {
-            String leftmostName = NodeUtil.getRootOfQualifiedName(n).getString();
-            Var v = t.getScope().getVar(leftmostName);
-            if (v != null && v.isLocal()) {
-              // Shadow of alias. Don't rewrite
+            if (isLeftmostNameLocal(t, n)) {
+              // The alias is shadowed by a local variable. Don't rewrite.
               return;
             }
             if (NodeUtil.isNameDeclOrSimpleAssignLhs(n, parent)) {
-              // Alias definition. Don't rewrite
+              // The node defines an alias. Don't rewrite.
               return;
             }
 
             Node newNode =
                 astFactory.createQName(t.getScope(), resolveAlias(n.getQualifiedName(), n));
+            if (isLeftmostNameLocal(t, newNode)) {
+              // The aliased name is shadowed by a local variable. Don't rewrite.
+              return;
+            }
 
             // If n is get_prop like "obj.foo" then newNode should use only location of foo, not
             // obj.foo.
@@ -163,6 +166,13 @@ public void visit(NodeTraversal t, Node n, Node parent) {
       }
     }
 
+    private boolean isLeftmostNameLocal(NodeTraversal t, Node n) {
+      Preconditions.checkState(n.isQualifiedName());
+      String leftmostName = NodeUtil.getRootOfQualifiedName(n).getString();
+      Var v = t.getScope().getVar(leftmostName);
+      return v != null && v.isLocal();
+    }
+
     /**
      * Use the alias table to look up the resolved name of the given alias. If the result is also an
      * alias repeat until the real name is resolved.

diff --git a/test/com/google/javascript/jscomp/InlineAliasesTest.java b/test/com/google/javascript/jscomp/InlineAliasesTest.java
@@ -618,4 +618,38 @@ public void testDoInlineEscapedConstructorProperty() {
                 "use(Foobar);",
                 "alert(Foobar.foo);")));
   }
+
+  @Test
+  public void testForwardedExport() {
+    testSame(
+        lines(
+            "const proto = {};",
+            "/** @const */",
+            "proto.google = {};",
+            "/** @const */",
+            "proto.google.type = {};",
+            "proto.google.type.Date = class {};",
+            "const alias = proto;",
+            "function f() {",
+            "  const d = new alias.google.type.Date();",
+            "  const proto = 0;",
+            "}"));
+  }
+
+  @Test
+  public void testForwardedExportNested() {
+    testSame(
+        lines(
+            "const proto = {};",
+            "/** @const */",
+            "proto.google = {};",
+            "/** @const */",
+            "proto.google.type = {};",
+            "proto.google.type.Date = class {};",
+            "const alias = proto.google;",
+            "function f() {",
+            "  const d = new alias.type.Date();",
+            "  const proto = 0;",
+            "}"));
+  }
 }