Allow concatenating compile-time constant strings via templates for Const.from

PiperOrigin-RevId: 326089965

Author: bangert

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

@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkState;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.Streams;
 import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
 import com.google.javascript.rhino.Node;
 
@@ -107,6 +108,7 @@ public void visit(NodeTraversal traversal, Node node, Node parent) {
    *
    * <ol>
    *   <li>The argument is a constant variable assigned from a string literal, or
+   *   <li>The argument is a template into which only string literals are inserted, or
    *   <li>The argument is an expression that is a string literal, or
    *   <li>The argument is a ternary expression choosing between string literals, or
    *   <li>The argument is a concatenation of the above.
@@ -118,6 +120,13 @@ public void visit(NodeTraversal traversal, Node node, Node parent) {
   private boolean isSafeValue(Scope scope, Node argument) {
     if (NodeUtil.isSomeCompileTimeConstStringValue(argument)) {
       return true;
+    } else if (argument.isTemplateLit()) {
+      // Each templateLit child is either a TemplateLitString, or has children which are substituted
+      return Streams.stream(argument.children())
+          .filter(node -> !node.isTemplateLitString())
+          .map(Node::children)
+          .flatMap(Streams::stream)
+          .allMatch(node -> isSafeValue(scope, node));
     } else if (argument.isAdd()) {
       Node left = argument.getFirstChild();
       Node right = argument.getLastChild();

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

@@ -81,6 +81,24 @@ public void testTemplateLiteralWithSubstitutionsArgument2() {
         ConstParamCheck.CONST_NOT_STRING_LITERAL_ERROR);
   }
 
+  @Test
+  public void testTemplateLiteralSubstitutesConstTemplate() {
+    testNoWarning(
+        CLOSURE_DEFS
+            + "var BAR = `bar`;" // An ESLint template
+            + "var FOO = `foo ${BAR}`;"
+            + "goog.string.Const.from(FOO);");
+  }
+
+  @Test
+  public void testTemplateLiteralSubstitutesConstString() {
+    testNoWarning(
+        CLOSURE_DEFS
+            + "var BAR = 'bar';" // A string literal
+            + "var FOO = `foo ${BAR}`;"
+            + "goog.string.Const.from(FOO);");
+  }
+
   @Test
   public void testConcatenatedStringLiteralArgument() {
     testSame(CLOSURE_DEFS