Merge pull request #27964 from Igorbek/issue27854

Fix bug in reduceEachChild for tagged template expressions

src/compiler/visitor.ts

@@ -1111,6 +1111,7 @@ namespace ts {
 
             case SyntaxKind.TaggedTemplateExpression:
                 result = reduceNode((<TaggedTemplateExpression>node).tag, cbNode, result);
+                result = reduceNodes((<TaggedTemplateExpression>node).typeArguments, cbNodes, result);
                 result = reduceNode((<TaggedTemplateExpression>node).template, cbNode, result);
                 break;
 

src/testRunner/unittests/transform.ts

@@ -40,6 +40,16 @@ namespace ts {
             return (file: SourceFile) => file;
         }
 
+        function replaceIdentifiersNamedOldNameWithNewName2(context: TransformationContext) {
+            const visitor: Visitor = (node) => {
+                if (isIdentifier(node) && node.text === "oldName") {
+                    return createIdentifier("newName");
+                }
+                return visitEachChild(node, visitor, context);
+            };
+            return (node: SourceFile) => visitNode(node, visitor);
+        }
+
         function transformSourceFile(sourceText: string, transformers: TransformerFactory<SourceFile>[]) {
             const transformed = transform(createSourceFile("source.ts", sourceText, ScriptTarget.ES2015), transformers);
             const printer = createPrinter({ newLine: NewLineKind.CarriageReturnLineFeed }, {
@@ -81,6 +91,18 @@ namespace ts {
             }).outputText;
         });
 
+        testBaseline("issue27854", () => {
+            return transpileModule(`oldName<{ a: string; }>\` ... \`;`, {
+                transformers: {
+                    before: [replaceIdentifiersNamedOldNameWithNewName2]
+                },
+                compilerOptions: {
+                    newLine: NewLineKind.CarriageReturnLineFeed,
+                    target: ScriptTarget.Latest
+                }
+            }).outputText;
+        });
+
         testBaseline("rewrittenNamespace", () => {
             return transpileModule(`namespace Reflect { const x = 1; }`, {
                 transformers: {

tests/baselines/reference/transformApi/transformsCorrectly.issue27854.js

@@ -0,0 +1 @@
+newName ` ... `;