Fix crash in name resolution with custom transforms and emitDecoratorMetadata

src/compiler/checker.ts

@@ -23454,6 +23454,15 @@ namespace ts {
         }
 
         function getTypeReferenceSerializationKind(typeName: EntityName, location?: Node): TypeReferenceSerializationKind {
+            // ensure both `typeName` and `location` are parse tree nodes.
+            typeName = getParseTreeNode(typeName, isEntityName);
+            if (!typeName) return TypeReferenceSerializationKind.Unknown;
+
+            if (location) {
+                location = getParseTreeNode(location);
+                if (!location) return TypeReferenceSerializationKind.Unknown;
+            }
+
             // Resolve the symbol as a value to ensure the type can be reached at runtime during emit.
             const valueSymbol = resolveEntityName(typeName, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ false, location);
 

src/compiler/transformers/ts.ts

@@ -1947,7 +1947,7 @@ namespace ts {
                     const name = getMutableClone(<Identifier>node);
                     name.flags &= ~NodeFlags.Synthesized;
                     name.original = undefined;
-                    name.parent = currentScope;
+                    name.parent = getParseTreeNode(currentScope); // ensure the parent is set to a parse tree node.
                     if (useFallback) {
                         return createLogicalAnd(
                             createStrictInequality(

src/harness/unittests/customTransforms.ts

@@ -3,12 +3,11 @@
 
 namespace ts {
     describe("customTransforms", () => {
-        function emitsCorrectly(name: string, sources: { file: string, text: string }[], customTransformers: CustomTransformers) {
+        function emitsCorrectly(name: string, sources: { file: string, text: string }[], customTransformers: CustomTransformers, options: CompilerOptions = {}) {
             it(name, () => {
                 const roots = sources.map(source => createSourceFile(source.file, source.text, ScriptTarget.ES2015));
                 const fileMap = arrayToMap(roots, file => file.fileName);
                 const outputs = createMap<string>();
-                const options: CompilerOptions = {};
                 const host: CompilerHost = {
                     getSourceFile: (fileName) => fileMap.get(fileName),
                     getDefaultLibFileName: () => "lib.d.ts",
@@ -82,5 +81,25 @@ namespace ts {
         emitsCorrectly("before", sources, { before: [before] });
         emitsCorrectly("after", sources, { after: [after] });
         emitsCorrectly("both", sources, { before: [before], after: [after] });
+
+        emitsCorrectly("before+decorators", [{
+            file: "source.ts",
+            text: `
+                declare const dec: any;
+                class B {}
+                @dec export class C { constructor(b: B) { } }
+                'change'
+            `
+        }], {before: [
+            context => node => visitNode(node, function visitor(node: Node): Node {
+                if (isStringLiteral(node) && node.text === "change") return createLiteral("changed");
+                return visitEachChild(node, visitor, context);
+            })
+        ]}, {
+            target: ScriptTarget.ES5,
+            module: ModuleKind.ES2015,
+            emitDecoratorMetadata: true,
+            experimentalDecorators: true
+         });
     });
 }