fix(ngcc): do not emit ES2015 code in ES5 files (#33514)

Previously, ngcc's `Renderer` would add some constants in the processed
files which were emitted as ES2015 code (e.g. `const` declarations).
This would result in invalid ES5 generated code that would break when
run on browsers that do not support the emitted format.

This commit fixes it by adding a `printStatement()` method to
`RenderingFormatter`, which can convert statements to JavaScript code in
a suitable format for the corresponding `RenderingFormatter`.
Additionally, the `translateExpression()` and `translateStatement()`
ngtsc helper methods are augmented to accept an extra hint to know
whether the code needs to be translated to ES5 format or not.

Fixes #32665

PR Close #33514

integration/ngcc/test.sh

@@ -95,7 +95,7 @@ assertSucceeded "Expected 'ngcc' to log 'Compiling'."
   grep "const ɵMatTable_BaseFactory = ɵngcc0.ɵɵgetInheritedFactory(MatTable);" node_modules/@angular/material/esm2015/table.js
   assertSucceeded "Expected 'ngcc' to generate a base factory for 'MatTable' in '@angular/material' (esm2015)."
 
-  grep "const ɵMatTable_BaseFactory = ɵngcc0.ɵɵgetInheritedFactory(MatTable);" node_modules/@angular/material/esm5/table.es5.js
+  grep "var ɵMatTable_BaseFactory = ɵngcc0.ɵɵgetInheritedFactory(MatTable);" node_modules/@angular/material/esm5/table.es5.js
   assertSucceeded "Expected 'ngcc' to generate a base factory for 'MatTable' in '@angular/material' (esm5)."
 
 

packages/compiler-cli/ngcc/src/rendering/esm5_rendering_formatter.ts

@@ -5,8 +5,11 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {Statement} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
+import {NOOP_DEFAULT_IMPORT_RECORDER} from '../../../src/ngtsc/imports';
+import {ImportManager, translateStatement} from '../../../src/ngtsc/translator';
 import {CompiledClass} from '../analysis/types';
 import {getIifeBody} from '../host/esm5_host';
 import {EsmRenderingFormatter} from './esm_rendering_formatter';
@@ -35,4 +38,22 @@ export class Esm5RenderingFormatter extends EsmRenderingFormatter {
     const insertionPoint = returnStatement.getFullStart();
     output.appendLeft(insertionPoint, '\n' + definitions);
   }
+
+  /**
+   * Convert a `Statement` to JavaScript code in a format suitable for rendering by this formatter.
+   *
+   * @param stmt The `Statement` to print.
+   * @param sourceFile A `ts.SourceFile` that provides context for the statement. See
+   *     `ts.Printer#printNode()` for more info.
+   * @param importManager The `ImportManager` to use for managing imports.
+   *
+   * @return The JavaScript code corresponding to `stmt` (in the appropriate format).
+   */
+  printStatement(stmt: Statement, sourceFile: ts.SourceFile, importManager: ImportManager): string {
+    const node =
+        translateStatement(stmt, importManager, NOOP_DEFAULT_IMPORT_RECORDER, ts.ScriptTarget.ES5);
+    const code = this.printer.printNode(ts.EmitHint.Unspecified, node, sourceFile);
+
+    return code;
+  }
 }

packages/compiler-cli/ngcc/src/rendering/esm_rendering_formatter.ts

@@ -5,10 +5,12 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {Statement} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
 import {relative, dirname, AbsoluteFsPath, absoluteFromSourceFile} from '../../../src/ngtsc/file_system';
-import {Import, ImportManager} from '../../../src/ngtsc/translator';
+import {NOOP_DEFAULT_IMPORT_RECORDER, Reexport} from '../../../src/ngtsc/imports';
+import {Import, ImportManager, translateStatement} from '../../../src/ngtsc/translator';
 import {isDtsPath} from '../../../src/ngtsc/util/src/typescript';
 import {CompiledClass} from '../analysis/types';
 import {NgccReflectionHost, POST_R3_MARKER, PRE_R3_MARKER, SwitchableVariableDeclaration} from '../host/ngcc_host';
@@ -16,13 +18,14 @@ import {ModuleWithProvidersInfo} from '../analysis/module_with_providers_analyze
 import {ExportInfo} from '../analysis/private_declarations_analyzer';
 import {RenderingFormatter, RedundantDecoratorMap} from './rendering_formatter';
 import {stripExtension} from './utils';
-import {Reexport} from '../../../src/ngtsc/imports';
 import {isAssignment} from '../host/esm2015_host';
 
 /**
  * A RenderingFormatter that works with ECMAScript Module import and export statements.
  */
 export class EsmRenderingFormatter implements RenderingFormatter {
+  protected printer = ts.createPrinter({newLine: ts.NewLineKind.LineFeed});
+
   constructor(protected host: NgccReflectionHost, protected isCore: boolean) {}
 
   /**
@@ -225,6 +228,24 @@ export class EsmRenderingFormatter implements RenderingFormatter {
     });
   }
 
+  /**
+   * Convert a `Statement` to JavaScript code in a format suitable for rendering by this formatter.
+   *
+   * @param stmt The `Statement` to print.
+   * @param sourceFile A `ts.SourceFile` that provides context for the statement. See
+   *     `ts.Printer#printNode()` for more info.
+   * @param importManager The `ImportManager` to use for managing imports.
+   *
+   * @return The JavaScript code corresponding to `stmt` (in the appropriate format).
+   */
+  printStatement(stmt: Statement, sourceFile: ts.SourceFile, importManager: ImportManager): string {
+    const node = translateStatement(
+        stmt, importManager, NOOP_DEFAULT_IMPORT_RECORDER, ts.ScriptTarget.ES2015);
+    const code = this.printer.printNode(ts.EmitHint.Unspecified, node, sourceFile);
+
+    return code;
+  }
+
   protected findEndOfImports(sf: ts.SourceFile): number {
     for (const stmt of sf.statements) {
       if (!ts.isImportDeclaration(stmt) && !ts.isImportEqualsDeclaration(stmt) &&

packages/compiler-cli/ngcc/src/rendering/renderer.ts

@@ -8,19 +8,18 @@
 import {ConstantPool, Expression, Statement, WrappedNodeExpr, WritePropExpr} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
-import {NOOP_DEFAULT_IMPORT_RECORDER} from '../../../src/ngtsc/imports';
-import {translateStatement, ImportManager} from '../../../src/ngtsc/translator';
+import {ImportManager} from '../../../src/ngtsc/translator';
 import {CompiledClass, CompiledFile, DecorationAnalyses} from '../analysis/types';
 import {PrivateDeclarationsAnalyses} from '../analysis/private_declarations_analyzer';
 import {SwitchMarkerAnalyses, SwitchMarkerAnalysis} from '../analysis/switch_marker_analyzer';
 import {IMPORT_PREFIX} from '../constants';
 import {FileSystem} from '../../../src/ngtsc/file_system';
-import {EntryPointBundle} from '../packages/entry_point_bundle';
+import {NgccReflectionHost} from '../host/ngcc_host';
 import {Logger} from '../logging/logger';
-import {FileToWrite, getImportRewriter, stripExtension} from './utils';
+import {EntryPointBundle} from '../packages/entry_point_bundle';
 import {RenderingFormatter, RedundantDecoratorMap} from './rendering_formatter';
 import {extractSourceMap, renderSourceAndMap} from './source_maps';
-import {NgccReflectionHost} from '../host/ngcc_host';
+import {FileToWrite, getImportRewriter, stripExtension} from './utils';
 
 /**
  * A base-class for rendering an `AnalyzedFile`.
@@ -98,7 +97,8 @@ export class Renderer {
 
       this.srcFormatter.addConstants(
           outputText,
-          renderConstantPool(compiledFile.sourceFile, compiledFile.constantPool, importManager),
+          renderConstantPool(
+              this.srcFormatter, compiledFile.sourceFile, compiledFile.constantPool, importManager),
           compiledFile.sourceFile);
     }
 
@@ -185,12 +185,9 @@ export class Renderer {
 
   private renderStatements(
       sourceFile: ts.SourceFile, statements: Statement[], imports: ImportManager): string {
-    const printer = createPrinter();
-    const translate = (stmt: Statement) =>
-        translateStatement(stmt, imports, NOOP_DEFAULT_IMPORT_RECORDER);
-    const print = (stmt: Statement) =>
-        printer.printNode(ts.EmitHint.Unspecified, translate(stmt), sourceFile);
-    return statements.map(print).join('\n');
+    const printStatement = (stmt: Statement) =>
+        this.srcFormatter.printStatement(stmt, sourceFile, imports);
+    return statements.map(printStatement).join('\n');
   }
 }
 
@@ -198,12 +195,10 @@ export class Renderer {
  * Render the constant pool as source code for the given class.
  */
 export function renderConstantPool(
-    sourceFile: ts.SourceFile, constantPool: ConstantPool, imports: ImportManager): string {
-  const printer = createPrinter();
-  return constantPool.statements
-      .map(stmt => translateStatement(stmt, imports, NOOP_DEFAULT_IMPORT_RECORDER))
-      .map(stmt => printer.printNode(ts.EmitHint.Unspecified, stmt, sourceFile))
-      .join('\n');
+    formatter: RenderingFormatter, sourceFile: ts.SourceFile, constantPool: ConstantPool,
+    imports: ImportManager): string {
+  const printStatement = (stmt: Statement) => formatter.printStatement(stmt, sourceFile, imports);
+  return constantPool.statements.map(printStatement).join('\n');
 }
 
 /**
@@ -216,7 +211,3 @@ function createAssignmentStatement(
   const receiver = new WrappedNodeExpr(receiverName);
   return new WritePropExpr(receiver, propName, initializer).toStmt();
 }
-
-function createPrinter(): ts.Printer {
-  return ts.createPrinter({newLine: ts.NewLineKind.LineFeed});
-}

packages/compiler-cli/ngcc/src/rendering/rendering_formatter.ts

@@ -5,6 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {Statement} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
 import {Reexport} from '../../../src/ngtsc/imports';
@@ -45,4 +46,5 @@ export interface RenderingFormatter {
   addModuleWithProvidersParams(
       outputText: MagicString, moduleWithProviders: ModuleWithProvidersInfo[],
       importManager: ImportManager): void;
+  printStatement(stmt: Statement, sourceFile: ts.SourceFile, importManager: ImportManager): string;
 }

packages/compiler-cli/ngcc/test/BUILD.bazel

@@ -10,6 +10,7 @@ ts_library(
         exclude = ["integration/**/*.ts"],
     ),
     deps = [
+        "//packages/compiler",
         "//packages/compiler-cli/ngcc",
         "//packages/compiler-cli/ngcc/test/helpers",
         "//packages/compiler-cli/src/ngtsc/diagnostics",

packages/compiler-cli/ngcc/test/integration/ngcc_spec.ts

@@ -147,6 +147,38 @@ runInEachFileSystem(() => {
               '{ bar: [{ type: Input }] });');
     });
 
+    it('should not add `const` in ES5 generated code', () => {
+      genNodeModules({
+        'test-package': {
+          '/index.ts': `
+            import {Directive, Input, NgModule} from '@angular/core';
+
+            @Directive({
+              selector: '[foo]',
+              host: {bar: ''},
+            })
+            export class FooDirective {
+            }
+
+            @NgModule({
+              declarations: [FooDirective],
+            })
+            export class FooModule {}
+          `,
+        },
+      });
+
+      mainNgcc({
+        basePath: '/node_modules',
+        targetEntryPointPath: 'test-package',
+        propertiesToConsider: ['main'],
+      });
+
+      const jsContents = fs.readFile(_(`/node_modules/test-package/index.js`));
+      expect(jsContents).not.toMatch(/\bconst \w+\s*=/);
+      expect(jsContents).toMatch(/\bvar _c0 =/);
+    });
+
     describe('in async mode', () => {
       it('should run ngcc without errors for fesm2015', async() => {
         const promise = mainNgcc({

packages/compiler-cli/ngcc/test/rendering/commonjs_rendering_formatter_spec.ts

@@ -5,6 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {DeclareVarStmt, LiteralExpr, StmtModifier} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
 import {NoopImportRewriter} from '../../../src/ngtsc/imports';
@@ -518,5 +519,19 @@ SOME DEFINITION TEXT
            expect(output.toString()).toContain(`function C() {\n    }\n    return C;`);
          });
     });
+
+    describe('printStatement', () => {
+      it('should transpile code to ES5', () => {
+        const {renderer, sourceFile, importManager} = setup(PROGRAM);
+
+        const stmt1 = new DeclareVarStmt('foo', new LiteralExpr(42), null, [StmtModifier.Static]);
+        const stmt2 = new DeclareVarStmt('bar', new LiteralExpr(true));
+        const stmt3 = new DeclareVarStmt('baz', new LiteralExpr('qux'), undefined, []);
+
+        expect(renderer.printStatement(stmt1, sourceFile, importManager)).toBe('var foo = 42;');
+        expect(renderer.printStatement(stmt2, sourceFile, importManager)).toBe('var bar = true;');
+        expect(renderer.printStatement(stmt3, sourceFile, importManager)).toBe('var baz = "qux";');
+      });
+    });
   });
 });

packages/compiler-cli/ngcc/test/rendering/dts_renderer_spec.ts

@@ -53,6 +53,7 @@ class TestRenderingFormatter implements RenderingFormatter {
       importManager: ImportManager): void {
     output.prepend('\n// ADD MODUlE WITH PROVIDERS PARAMS\n');
   }
+  printStatement(): string { return 'IGNORED'; }
 }
 
 function createTestRenderer(
@@ -87,6 +88,7 @@ function createTestRenderer(
   spyOn(testFormatter, 'removeDecorators').and.callThrough();
   spyOn(testFormatter, 'rewriteSwitchableDeclarations').and.callThrough();
   spyOn(testFormatter, 'addModuleWithProvidersParams').and.callThrough();
+  spyOn(testFormatter, 'printStatement').and.callThrough();
 
   const renderer = new DtsRenderer(testFormatter, fs, logger, host, bundle);
 

packages/compiler-cli/ngcc/test/rendering/esm5_rendering_formatter_spec.ts

@@ -5,6 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {DeclareVarStmt, LiteralExpr, StmtModifier} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
 import {NoopImportRewriter} from '../../../src/ngtsc/imports';
@@ -545,5 +546,19 @@ SOME DEFINITION TEXT
            });
       });
     });
+
+    describe('printStatement', () => {
+      it('should transpile code to ES5', () => {
+        const {renderer, sourceFile, importManager} = setup(PROGRAM);
+
+        const stmt1 = new DeclareVarStmt('foo', new LiteralExpr(42), null, [StmtModifier.Static]);
+        const stmt2 = new DeclareVarStmt('bar', new LiteralExpr(true));
+        const stmt3 = new DeclareVarStmt('baz', new LiteralExpr('qux'), undefined, []);
+
+        expect(renderer.printStatement(stmt1, sourceFile, importManager)).toBe('var foo = 42;');
+        expect(renderer.printStatement(stmt2, sourceFile, importManager)).toBe('var bar = true;');
+        expect(renderer.printStatement(stmt3, sourceFile, importManager)).toBe('var baz = "qux";');
+      });
+    });
   });
 });

packages/compiler-cli/ngcc/test/rendering/esm_rendering_formatter_spec.ts

@@ -5,6 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {DeclareVarStmt, LiteralExpr, StmtModifier} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
 import {NoopImportRewriter} from '../../../src/ngtsc/imports';
@@ -623,5 +624,19 @@ export { D };
           static withProviders2(): (ModuleWithProviders)&{ngModule:ExternalModule};`);
          });
     });
+
+    describe('printStatement', () => {
+      it('should transpile code to ES2015', () => {
+        const {renderer, sourceFile, importManager} = setup([PROGRAM]);
+
+        const stmt1 = new DeclareVarStmt('foo', new LiteralExpr(42), null, [StmtModifier.Final]);
+        const stmt2 = new DeclareVarStmt('bar', new LiteralExpr(true));
+        const stmt3 = new DeclareVarStmt('baz', new LiteralExpr('qux'), undefined, []);
+
+        expect(renderer.printStatement(stmt1, sourceFile, importManager)).toBe('const foo = 42;');
+        expect(renderer.printStatement(stmt2, sourceFile, importManager)).toBe('var bar = true;');
+        expect(renderer.printStatement(stmt3, sourceFile, importManager)).toBe('var baz = "qux";');
+      });
+    });
   });
 });

packages/compiler-cli/ngcc/test/rendering/renderer_spec.ts

@@ -5,14 +5,15 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {Statement} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
 import {fromObject, generateMapFileComment, SourceMapConverter} from 'convert-source-map';
 import {absoluteFrom, getFileSystem} from '../../../src/ngtsc/file_system';
 import {TestFile, runInEachFileSystem} from '../../../src/ngtsc/file_system/testing';
-import {Reexport} from '../../../src/ngtsc/imports';
+import {NOOP_DEFAULT_IMPORT_RECORDER, Reexport} from '../../../src/ngtsc/imports';
 import {loadTestFiles} from '../../../test/helpers';
-import {Import, ImportManager} from '../../../src/ngtsc/translator';
+import {Import, ImportManager, translateStatement} from '../../../src/ngtsc/translator';
 import {DecorationAnalyzer} from '../../src/analysis/decoration_analyzer';
 import {CompiledClass} from '../../src/analysis/types';
 import {NgccReferencesRegistry} from '../../src/analysis/ngcc_references_registry';
@@ -27,6 +28,8 @@ import {RenderingFormatter, RedundantDecoratorMap} from '../../src/rendering/ren
 import {makeTestEntryPointBundle, getRootFiles} from '../helpers/utils';
 
 class TestRenderingFormatter implements RenderingFormatter {
+  private printer = ts.createPrinter({newLine: ts.NewLineKind.LineFeed});
+
   addImports(output: MagicString, imports: Import[], sf: ts.SourceFile) {
     output.prepend('\n// ADD IMPORTS\n');
   }
@@ -56,6 +59,13 @@ class TestRenderingFormatter implements RenderingFormatter {
       importManager: ImportManager): void {
     output.prepend('\n// ADD MODUlE WITH PROVIDERS PARAMS\n');
   }
+  printStatement(stmt: Statement, sourceFile: ts.SourceFile, importManager: ImportManager): string {
+    const node = translateStatement(
+        stmt, importManager, NOOP_DEFAULT_IMPORT_RECORDER, ts.ScriptTarget.ES2015);
+    const code = this.printer.printNode(ts.EmitHint.Unspecified, node, sourceFile);
+
+    return `// TRANSPILED\n${code}`;
+  }
 }
 
 function createTestRenderer(
@@ -92,6 +102,7 @@ function createTestRenderer(
   spyOn(testFormatter, 'removeDecorators').and.callThrough();
   spyOn(testFormatter, 'rewriteSwitchableDeclarations').and.callThrough();
   spyOn(testFormatter, 'addModuleWithProvidersParams').and.callThrough();
+  spyOn(testFormatter, 'printStatement').and.callThrough();
 
   const renderer = new Renderer(host, testFormatter, fs, logger, bundle);
 
@@ -200,8 +211,9 @@ runInEachFileSystem(() => {
         renderer.renderProgram(
             decorationAnalyses, switchMarkerAnalyses, privateDeclarationsAnalyses);
         const addDefinitionsSpy = testFormatter.addDefinitions as jasmine.Spy;
-        expect(addDefinitionsSpy.calls.first().args[2])
-            .toEqual(`A.ɵfac = function A_Factory(t) { return new (t || A)(); };
+        expect(addDefinitionsSpy.calls.first().args[2]).toEqual(`// TRANSPILED
+A.ɵfac = function A_Factory(t) { return new (t || A)(); };
+// TRANSPILED
 A.ɵcmp = ɵngcc0.ɵɵdefineComponent({ type: A, selectors: [["a"]], decls: 1, vars: 1, template: function A_Template(rf, ctx) { if (rf & 1) {
         ɵngcc0.ɵɵtext(0);
     } if (rf & 2) {
@@ -209,8 +221,8 @@ A.ɵcmp = ɵngcc0.ɵɵdefineComponent({ type: A, selectors: [["a"]], decls: 1, v
     } }, encapsulation: 2 });`);
 
         const addAdjacentStatementsSpy = testFormatter.addAdjacentStatements as jasmine.Spy;
-        expect(addAdjacentStatementsSpy.calls.first().args[2])
-            .toEqual(`/*@__PURE__*/ ɵngcc0.ɵsetClassMetadata(A, [{
+        expect(addAdjacentStatementsSpy.calls.first().args[2]).toEqual(`// TRANSPILED
+/*@__PURE__*/ ɵngcc0.ɵsetClassMetadata(A, [{
         type: Component,
         args: [{ selector: 'a', template: '{{ person!.name }}' }]
     }], null, null);`);
@@ -243,8 +255,9 @@ A.ɵcmp = ɵngcc0.ɵɵdefineComponent({ type: A, selectors: [["a"]], decls: 1, v
                name: 'A',
                decorators: [jasmine.objectContaining({name: 'Directive'})]
              }));
-             expect(addDefinitionsSpy.calls.first().args[2])
-                 .toEqual(`A.ɵfac = function A_Factory(t) { return new (t || A)(); };
+             expect(addDefinitionsSpy.calls.first().args[2]).toEqual(`// TRANSPILED
+A.ɵfac = function A_Factory(t) { return new (t || A)(); };
+// TRANSPILED
 A.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: A, selectors: [["", "a", ""]] });`);
            });
 
@@ -260,8 +273,8 @@ A.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: A, selectors: [["", "a", ""]] });`
              expect(addAdjacentStatementsSpy.calls.first().args[1])
                  .toEqual(jasmine.objectContaining(
                      {name: 'A', decorators: [jasmine.objectContaining({name: 'Directive'})]}));
-             expect(addAdjacentStatementsSpy.calls.first().args[2])
-                 .toEqual(`/*@__PURE__*/ ɵngcc0.ɵsetClassMetadata(A, [{
+             expect(addAdjacentStatementsSpy.calls.first().args[2]).toEqual(`// TRANSPILED
+/*@__PURE__*/ ɵngcc0.ɵsetClassMetadata(A, [{
         type: Directive,
         args: [{ selector: '[a]' }]
     }], null, null);`);
@@ -271,7 +284,7 @@ A.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: A, selectors: [["", "a", ""]] });`
            () => {
              const {renderer, decorationAnalyses, switchMarkerAnalyses, privateDeclarationsAnalyses,
                     testFormatter} = createTestRenderer('test-package', [INPUT_PROGRAM]);
-             const result = renderer.renderProgram(
+             renderer.renderProgram(
                  decorationAnalyses, switchMarkerAnalyses, privateDeclarationsAnalyses);
              const removeDecoratorsSpy = testFormatter.removeDecorators as jasmine.Spy;
              expect(removeDecoratorsSpy.calls.first().args[0].toString())
@@ -467,9 +480,9 @@ A.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: A, selectors: [["", "a", ""]] });`
               decorationAnalyses, switchMarkerAnalyses, privateDeclarationsAnalyses);
 
           const addDefinitionsSpy = testFormatter.addDefinitions as jasmine.Spy;
-          expect(addDefinitionsSpy.calls.first().args[2])
-              .toEqual(
-                  `UndecoratedBase.ɵfac = function UndecoratedBase_Factory(t) { return new (t || UndecoratedBase)(); };
+          expect(addDefinitionsSpy.calls.first().args[2]).toEqual(`// TRANSPILED
+UndecoratedBase.ɵfac = function UndecoratedBase_Factory(t) { return new (t || UndecoratedBase)(); };
+// TRANSPILED
 UndecoratedBase.ɵdir = ɵngcc0.ɵɵdefineDirective({ type: UndecoratedBase, viewQuery: function UndecoratedBase_Query(rf, ctx) { if (rf & 1) {
         ɵngcc0.ɵɵstaticViewQuery(_c0, true);
     } if (rf & 2) {

packages/compiler-cli/ngcc/test/rendering/umd_rendering_formatter_spec.ts

@@ -5,6 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
+import {DeclareVarStmt, LiteralExpr, StmtModifier} from '@angular/compiler';
 import MagicString from 'magic-string';
 import * as ts from 'typescript';
 import {NoopImportRewriter} from '../../../src/ngtsc/imports';
@@ -592,5 +593,19 @@ SOME DEFINITION TEXT
            expect(output.toString()).toContain(`function C() {\n      }\n      return C;`);
          });
     });
+
+    describe('printStatement', () => {
+      it('should transpile code to ES5', () => {
+        const {renderer, sourceFile, importManager} = setup(PROGRAM);
+
+        const stmt1 = new DeclareVarStmt('foo', new LiteralExpr(42), null, [StmtModifier.Static]);
+        const stmt2 = new DeclareVarStmt('bar', new LiteralExpr(true));
+        const stmt3 = new DeclareVarStmt('baz', new LiteralExpr('qux'), undefined, []);
+
+        expect(renderer.printStatement(stmt1, sourceFile, importManager)).toBe('var foo = 42;');
+        expect(renderer.printStatement(stmt2, sourceFile, importManager)).toBe('var bar = true;');
+        expect(renderer.printStatement(stmt3, sourceFile, importManager)).toBe('var baz = "qux";');
+      });
+    });
   });
 });

packages/compiler-cli/src/ngtsc/annotations/test/metadata_spec.ts

@@ -119,7 +119,8 @@ runInEachFileSystem(() => {
     }
     const sf = getSourceFileOrError(program, _('/index.ts'));
     const im = new ImportManager(new NoopImportRewriter(), 'i');
-    const tsStatement = translateStatement(call, im, NOOP_DEFAULT_IMPORT_RECORDER);
+    const tsStatement =
+        translateStatement(call, im, NOOP_DEFAULT_IMPORT_RECORDER, ts.ScriptTarget.ES2015);
     const res = ts.createPrinter().printNode(ts.EmitHint.Unspecified, tsStatement, sf);
     return res.replace(/\s+/g, ' ');
   }

packages/compiler-cli/src/ngtsc/transform/src/transform.ts

@@ -64,8 +64,9 @@ class IvyVisitor extends Visitor {
 
       res.forEach(field => {
         // Translate the initializer for the field into TS nodes.
-        const exprNode =
-            translateExpression(field.initializer, this.importManager, this.defaultImportRecorder);
+        const exprNode = translateExpression(
+            field.initializer, this.importManager, this.defaultImportRecorder,
+            ts.ScriptTarget.ES2015);
 
         // Create a static property declaration for the new field.
         const property = ts.createProperty(
@@ -73,7 +74,9 @@ class IvyVisitor extends Visitor {
             undefined, exprNode);
 
         field.statements
-            .map(stmt => translateStatement(stmt, this.importManager, this.defaultImportRecorder))
+            .map(
+                stmt => translateStatement(
+                    stmt, this.importManager, this.defaultImportRecorder, ts.ScriptTarget.ES2015))
             .forEach(stmt => statements.push(stmt));
 
         members.push(property);
@@ -218,7 +221,8 @@ function transformIvySourceFile(
   // Generate the constant statements first, as they may involve adding additional imports
   // to the ImportManager.
   const constants = constantPool.statements.map(
-      stmt => translateStatement(stmt, importManager, defaultImportRecorder));
+      stmt =>
+          translateStatement(stmt, importManager, defaultImportRecorder, ts.ScriptTarget.ES2015));
 
   // Preserve @fileoverview comments required by Closure, since the location might change as a
   // result of adding extra imports and constant pool statements.

packages/compiler-cli/src/ngtsc/translator/src/translator.ts

@@ -100,17 +100,19 @@ export class ImportManager {
 }
 
 export function translateExpression(
-    expression: Expression, imports: ImportManager,
-    defaultImportRecorder: DefaultImportRecorder): ts.Expression {
+    expression: Expression, imports: ImportManager, defaultImportRecorder: DefaultImportRecorder,
+    scriptTarget: Exclude<ts.ScriptTarget, ts.ScriptTarget.JSON>): ts.Expression {
   return expression.visitExpression(
-      new ExpressionTranslatorVisitor(imports, defaultImportRecorder), new Context(false));
+      new ExpressionTranslatorVisitor(imports, defaultImportRecorder, scriptTarget),
+      new Context(false));
 }
 
 export function translateStatement(
-    statement: Statement, imports: ImportManager,
-    defaultImportRecorder: DefaultImportRecorder): ts.Statement {
+    statement: Statement, imports: ImportManager, defaultImportRecorder: DefaultImportRecorder,
+    scriptTarget: Exclude<ts.ScriptTarget, ts.ScriptTarget.JSON>): ts.Statement {
   return statement.visitStatement(
-      new ExpressionTranslatorVisitor(imports, defaultImportRecorder), new Context(true));
+      new ExpressionTranslatorVisitor(imports, defaultImportRecorder, scriptTarget),
+      new Context(true));
 }
 
 export function translateType(type: Type, imports: ImportManager): ts.TypeNode {
@@ -120,10 +122,14 @@ export function translateType(type: Type, imports: ImportManager): ts.TypeNode {
 class ExpressionTranslatorVisitor implements ExpressionVisitor, StatementVisitor {
   private externalSourceFiles = new Map<string, ts.SourceMapSource>();
   constructor(
-      private imports: ImportManager, private defaultImportRecorder: DefaultImportRecorder) {}
+      private imports: ImportManager, private defaultImportRecorder: DefaultImportRecorder,
+      private scriptTarget: Exclude<ts.ScriptTarget, ts.ScriptTarget.JSON>) {}
 
   visitDeclareVarStmt(stmt: DeclareVarStmt, context: Context): ts.VariableStatement {
-    const nodeFlags = stmt.hasModifier(StmtModifier.Final) ? ts.NodeFlags.Const : ts.NodeFlags.None;
+    const nodeFlags =
+        ((this.scriptTarget >= ts.ScriptTarget.ES2015) && stmt.hasModifier(StmtModifier.Final)) ?
+        ts.NodeFlags.Const :
+        ts.NodeFlags.None;
     return ts.createVariableStatement(
         undefined, ts.createVariableDeclarationList(
                        [ts.createVariableDeclaration(
@@ -149,6 +155,11 @@ class ExpressionTranslatorVisitor implements ExpressionVisitor, StatementVisitor
   }
 
   visitDeclareClassStmt(stmt: ClassStmt, context: Context) {
+    if (this.scriptTarget < ts.ScriptTarget.ES2015) {
+      throw new Error(
+          `Unsupported mode: Visiting a "declare class" statement (class ${stmt.name}) while ` +
+          `targeting ${ts.ScriptTarget[this.scriptTarget]}.`);
+    }
     throw new Error('Method not implemented.');
   }
 
@@ -200,7 +211,7 @@ class ExpressionTranslatorVisitor implements ExpressionVisitor, StatementVisitor
     const exprContext = context.withExpressionMode;
     const lhs = ts.createElementAccess(
         expr.receiver.visitExpression(this, exprContext),
-        expr.index.visitExpression(this, exprContext), );
+        expr.index.visitExpression(this, exprContext));
     const rhs = expr.value.visitExpression(this, exprContext);
     const result: ts.Expression = ts.createBinary(lhs, ts.SyntaxKind.EqualsToken, rhs);
     return context.isStatement ? result : ts.createParen(result);
@@ -252,6 +263,12 @@ class ExpressionTranslatorVisitor implements ExpressionVisitor, StatementVisitor
   }
 
   visitLocalizedString(ast: LocalizedString, context: Context): ts.Expression {
+    if (this.scriptTarget < ts.ScriptTarget.ES2015) {
+      // This should never happen.
+      throw new Error(
+          'Unsupported mode: Visiting a localized string (which produces a tagged template ' +
+          `literal) ' while targeting ${ts.ScriptTarget[this.scriptTarget]}.`);
+    }
     return visitLocalizedString(ast, context, this);
   }
 
@@ -518,7 +535,8 @@ export class TypeTranslatorVisitor implements ExpressionVisitor, TypeVisitor {
   }
 
   visitTypeofExpr(ast: TypeofExpr, context: Context): ts.TypeQueryNode {
-    let expr = translateExpression(ast.expr, this.imports, NOOP_DEFAULT_IMPORT_RECORDER);
+    let expr = translateExpression(
+        ast.expr, this.imports, NOOP_DEFAULT_IMPORT_RECORDER, ts.ScriptTarget.ES2015);
     return ts.createTypeQueryNode(expr as ts.Identifier);
   }
 }

packages/compiler-cli/src/ngtsc/typecheck/src/environment.ts

@@ -204,7 +204,8 @@ export class Environment {
     const ngExpr = this.refEmitter.emit(ref, this.contextFile);
 
     // Use `translateExpression` to convert the `Expression` into a `ts.Expression`.
-    return translateExpression(ngExpr, this.importManager, NOOP_DEFAULT_IMPORT_RECORDER);
+    return translateExpression(
+        ngExpr, this.importManager, NOOP_DEFAULT_IMPORT_RECORDER, ts.ScriptTarget.ES2015);
   }
 
   /**