Cherry-pick PR #38500 into release-3.9

Component commits:
ee3f2ce362 regression(38485): allow using rawText property in processing a tagged template

src/compiler/transformers/taggedTemplate.ts

@@ -71,18 +71,21 @@ namespace ts {
      *
      * @param node The ES6 template literal.
      */
-    function getRawLiteral(node: LiteralLikeNode, currentSourceFile: SourceFile) {
+    function getRawLiteral(node: TemplateLiteralLikeNode, currentSourceFile: SourceFile) {
         // Find original source text, since we need to emit the raw strings of the tagged template.
         // The raw strings contain the (escaped) strings of what the user wrote.
         // Examples: `\n` is converted to "\\n", a template string with a newline to "\n".
-        let text = getSourceTextOfNodeFromSourceFile(currentSourceFile, node);
+        let text = node.rawText;
+        if (text === undefined) {
+            text = getSourceTextOfNodeFromSourceFile(currentSourceFile, node);
 
-        // text contains the original source, it will also contain quotes ("`"), dolar signs and braces ("${" and "}"),
-        // thus we need to remove those characters.
-        // First template piece starts with "`", others with "}"
-        // Last template piece ends with "`", others with "${"
-        const isLast = node.kind === SyntaxKind.NoSubstitutionTemplateLiteral || node.kind === SyntaxKind.TemplateTail;
-        text = text.substring(1, text.length - (isLast ? 1 : 2));
+            // text contains the original source, it will also contain quotes ("`"), dolar signs and braces ("${" and "}"),
+            // thus we need to remove those characters.
+            // First template piece starts with "`", others with "}"
+            // Last template piece ends with "`", others with "${"
+            const isLast = node.kind === SyntaxKind.NoSubstitutionTemplateLiteral || node.kind === SyntaxKind.TemplateTail;
+            text = text.substring(1, text.length - (isLast ? 1 : 2));
+        }
 
         // Newline normalization:
         // ES6 Spec 11.8.6.1 - Static Semantics of TV's and TRV's

src/testRunner/unittests/transform.ts

@@ -50,6 +50,15 @@ namespace ts {
             return (node: SourceFile) => visitNode(node, visitor);
         }
 
+        function createTaggedTemplateLiteral(): Transformer<SourceFile> {
+            return sourceFile => updateSourceFileNode(sourceFile, [
+                createStatement(
+                    createTaggedTemplate(
+                        createIdentifier("$tpl"),
+                        createNoSubstitutionTemplateLiteral("foo", "foo")))
+            ]);
+        }
+
         function transformSourceFile(sourceText: string, transformers: TransformerFactory<SourceFile>[]) {
             const transformed = transform(createSourceFile("source.ts", sourceText, ScriptTarget.ES2015), transformers);
             const printer = createPrinter({ newLine: NewLineKind.CarriageReturnLineFeed }, {
@@ -120,6 +129,17 @@ namespace ts {
             }).outputText;
         });
 
+        testBaseline("transformTaggedTemplateLiteral", () => {
+            return transpileModule("", {
+                transformers: {
+                    before: [createTaggedTemplateLiteral],
+                },
+                compilerOptions: {
+                    target: ScriptTarget.ES5
+                }
+            }).outputText;
+        });
+
         testBaseline("issue27854", () => {
             return transpileModule(`oldName<{ a: string; }>\` ... \`;`, {
                 transformers: {

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

@@ -0,0 +1,5 @@
+var __makeTemplateObject = (this && this.__makeTemplateObject) || function (cooked, raw) {
+    if (Object.defineProperty) { Object.defineProperty(cooked, "raw", { value: raw }); } else { cooked.raw = raw; }
+    return cooked;
+};
+$tpl(__makeTemplateObject(["foo"], ["foo"]));