Inject call to createTemplateTagFirstArg() at the nearest SCRIPT scoped node

Currently we inject the calls to createTemplateTagFirstArg at beginning of the SCRIPT which contains a tagged template literal. This creates a runtime error for tagged template literals used in the first SCRIPT.

PiperOrigin-RevId: 309995860

Author: rishipal

src/com/google/javascript/jscomp/Es6TemplateLiterals.java

@@ -15,6 +15,7 @@
  */
 package com.google.javascript.jscomp;
 
+import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.javascript.jscomp.Es6ToEs3Util.createGenericType;
 import static com.google.javascript.jscomp.Es6ToEs3Util.createType;
@@ -158,8 +159,12 @@ void visitTaggedTemplateLiteral(NodeTraversal t, Node n, boolean addTypes) {
             .createSingleVarNameDeclaration(TEMPLATELIT_VAR + uniqueId, callTemplateTagArgCreator)
             .setJSDocInfo(info)
             .useSourceInfoIfMissingFromForTree(n);
-    Node script = NodeUtil.getEnclosingScript(n);
-    script.addChildToFront(tagFnFirstArgDeclaration);
+
+    // Get the nearest SCRIPT-scoped node as insertion point for this assignment as injecting to the
+    // top of the script causes runtime errors
+    // https://github.com/google/closure-compiler/issues/3589
+    Node insertionPoint = findInsertionPoint(n);
+    insertionPoint.getParent().addChildBefore(tagFnFirstArgDeclaration, insertionPoint);
     t.reportCodeChange(tagFnFirstArgDeclaration);
 
     // Generate the call expression.
@@ -186,6 +191,21 @@ private Node createRawStringArray(Node n, JSType arrayType) {
     return array;
   }
 
+  /**
+   * Finds the closest enclosing node whose parent is a SCRIPT. We'll want to insert the call to
+   * `var tagFnFirstArg = $jscomp.createTemplateTagFirstArg...` just before that one.
+   */
+  private static Node findInsertionPoint(Node n) {
+    Node insertionPoint = n;
+    Node insertionParent = checkNotNull(insertionPoint.getParent(), n);
+    while (!insertionParent.isScript()) {
+      insertionPoint = insertionParent;
+      insertionParent = checkNotNull(insertionPoint.getParent(), insertionPoint);
+    }
+    checkState(insertionParent.isScript(), insertionParent);
+    return insertionPoint;
+  }
+
   private Node createCookedStringArray(Node n, JSType templateArrayType) {
     Node array = withType(IR.arraylit(), templateArrayType);
     for (Node child = n.getFirstChild(); child != null; child = child.getNext()) {

test/com/google/javascript/jscomp/LateEs6ToEs3ConverterTest.java

@@ -357,6 +357,36 @@ public void testTaggedTemplateLiteral() {
             "tag(TAGGED_TEMPLATE_TMP_VAR$0);"));
   }
 
+  @Test
+  public void testTaggedTemplateLiteral_InsertPosition() {
+    // inserted at the directly enclosing script scope
+    taggedTemplateLiteral_TestRunner(
+        lines("var a = {};", "tag``;"),
+        lines(
+            "var a = {};",
+            "/** @noinline */ var TAGGED_TEMPLATE_TMP_VAR$0 =",
+            "    $jscomp.createTemplateTagFirstArg(['']);",
+            "tag(TAGGED_TEMPLATE_TMP_VAR$0);"));
+
+    // inserted at the script scope above the immediate enclosing function at the script scope
+    taggedTemplateLiteral_TestRunner(
+        lines("var a = {};", "function foo() {tag``;}"),
+        lines(
+            "var a = {};",
+            "/** @noinline */ var TAGGED_TEMPLATE_TMP_VAR$0 =",
+            "    $jscomp.createTemplateTagFirstArg(['']);",
+            "function foo() {tag(TAGGED_TEMPLATE_TMP_VAR$0);}"));
+
+    // inserted at the script scope above the outer enclosing function at the script scope
+    taggedTemplateLiteral_TestRunner(
+        lines("var a = {};", "function foo() {function bar() {tag``;}}"),
+        lines(
+            "var a = {};",
+            "/** @noinline */ var TAGGED_TEMPLATE_TMP_VAR$0 =",
+            "    $jscomp.createTemplateTagFirstArg(['']);",
+            "function foo() {function bar() {tag(TAGGED_TEMPLATE_TMP_VAR$0);}}"));
+  }
+
   @Test
   public void testUnicodeEscapes() {
     test("var \\u{73} = \'\\u{2603}\'", "var s = \'\u2603\'");  // ☃