Don't convert goog.object.createSet calls with one argument to object…

… literals

The method spec says:
If only one argument is provided and it is an array then this is used as the arguments, otherwise the arguments are used as the property names.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=225461926

src/com/google/javascript/jscomp/ClosureOptimizePrimitives.java

@@ -190,6 +190,15 @@ private void processObjectCreateSetCall(Node callNode) {
    * Returns whether the given call to goog.object.createSet can be converted to an object literal.
    */
   private boolean canOptimizeObjectCreateSet(Node firstParam) {
+    if (firstParam != null
+        && firstParam.getNext() == null
+        && !(firstParam.isNumber() || firstParam.isString())) {
+      // if there is only one argument, and it's an array, then the method uses the array elements
+      // as keys. Don't optimize it to {[arr]: true}. We only special-case number and string
+      // arguments in order to not regress ES5-out behavior
+      return false;
+    }
+
     Node curParam = firstParam;
     Set<String> keys = new HashSet<>();
     while (curParam != null) {

test/com/google/javascript/jscomp/ClosureOptimizePrimitivesTest.java

@@ -115,23 +115,23 @@ public void testObjectCreateNonConstKeyNotEs6() {
   }
 
   @Test
-  public void testObjectCreateSet1() {
+  public void testObjectCreateSetZeroArg() {
     test("var a = goog.object.createSet()", "var a = {}");
   }
 
   @Test
-  public void testObjectCreateSet2() {
+  public void testObjectCreateSetTwoNumericalArgs() {
     test("var a = goog.object.createSet(1,2)", "var a = {1:true,2:true}");
   }
 
   @Test
-  public void testObjectCreateSet3() {
+  public void testObjectCreateSetOneNumericalArg() {
     test("alert(goog.object.createSet(1).toString())",
          "alert({1:true}.toString())");
   }
 
   @Test
-  public void testObjectCreateSet4() {
+  public void testObjectCreateSetOneStringArg() {
     test("goog.object.createSet('a').toString()", "({'a':true}).toString()");
   }
 
@@ -155,9 +155,9 @@ public void testObjectCreateSetNonConstKey2() {
   }
 
   @Test
-  public void testObjectCreateSetNonConstKey3() {
-    test("goog.object.createSet(() => {}).toString()",
-        "({[() => {}]: true}).toString()");
+  public void testObjectCreateSetNonConstSingleKey() {
+    // this triggers the 'first argument may be an array' case and we back off
+    testSame("goog.object.createSet(() => {}).toString()");
   }
 
   @Test
@@ -166,6 +166,19 @@ public void testObjectCreateSetNonConstKeyNotEs6() {
     testSame("var a = goog.object.createSet(foo, bar);");
   }
 
+  @Test
+  public void testObjectCreateSetSingleNonLiteralArg() {
+    testSame("const arr = [1, 2, 3]; const s = goog.object.createSet(arr);");
+    testSame("const num = 1; const s = goog.object.createSet(num);");
+    testSame("const s = goog.object.createSet(undefined || [1, 2, 3]);");
+  }
+
+  @Test
+  public void testObjectCreateSetSingleLiteralArg() {
+    test("const s = goog.object.createSet(3);", "const s = {3: true};");
+    test("const s = goog.object.createSet('a');", "const s = {'a': true};");
+  }
+
   @Test
   public void testDomTagName() {
     testSame("goog.dom.TagName.A = 'A';");
@@ -190,11 +203,13 @@ public void testPropertyReflectionAdvanced() {
   }
 
   @Test
-  public void testEs6Compatibility() {
+  public void testEs6ArrowCompatibility() {
     // Arrow
     test("var f = () => goog.object.create(1, 2);", "var f = () => ({1: 2});");
+  }
 
-    // Class
+  @Test
+  public void testEs6ClassCompatibility() {
     test(
         lines(
             "class C {",
@@ -208,8 +223,10 @@ public void testEs6Compatibility() {
             "    this.x = {1: 2};",
             "  }",
             "}"));
+  }
 
-    // Shorthand methods
+  @Test
+  public void testEs6MemberFunctionDefCompatibility() {
     test(
         lines(
             "var obj = {",
@@ -223,8 +240,10 @@ public void testEs6Compatibility() {
             "    return {'a': 2};",
             "  }",
             "}"));
+  }
 
-    // Computed Prop
+  @Test
+  public void testEs6ComputedPropCompatibility() {
     test(
         lines(
             "var obj = {",
@@ -234,8 +253,10 @@ public void testEs6Compatibility() {
             "var obj = {",
             "  [{1: 2}]: 42",
             "}"));
+  }
 
-    // Template Literals
+  @Test
+  public void testEs6TemplateLitCompatibility() {
     test(
         lines(
             "function tag(strings) {",
@@ -247,11 +268,15 @@ public void testEs6Compatibility() {
             "  return {'a': 2};",
             "}",
             "tag`template`"));
+  }
 
-    // Destructuring
+  @Test
+  public void testEs6DestructuringCompatibility() {
     test("var {a: x} = goog.object.create('a', 2);", "var {a: x} = {'a': 2};");
+  }
 
-    // Async
+  @Test
+  public void testEs6AsyncCompatibility() {
     test(
         lines(
             "async function foo() {",