From 550433a128cfca4e7d3d0c786a293e8799e521c7 Mon Sep 17 00:00:00 2001
From: Alex Rickabaugh <alx+alxhub@alxandria.net>
Date: Fri, 30 Mar 2018 08:02:30 -0700
Subject: [PATCH] feat(compiler-cli): lower loadChildren fields to allow
 dynamic module paths (#23088)

Computing the value of loadChildren does not work externally, as the CLI
needs to be able to detect the paths referenced to properly set up
codesplitting. However, internally, different approaches to codesplitting
require hashed module IDs, and the computation of those hashes involves
something like:

{path: '...', loadChildren: hashFn('module')}

ngc should lower loadChildren into an exported constant in that case.

This will never break externally, because loadChildren is always a
string externally, and a string won't get lowered.

PR Close #23088
---
 .../compiler-cli/src/transformers/program.ts  |  2 +-
 packages/compiler-cli/test/BUILD.bazel        |  1 +
 packages/compiler-cli/test/ngc_spec.ts        | 34 +++++++++++++++++++
 packages/compiler/src/aot/static_reflector.ts |  2 +-
 4 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/packages/compiler-cli/src/transformers/program.ts b/packages/compiler-cli/src/transformers/program.ts
index b10c8b8027..b6f07b4a91 100644
--- a/packages/compiler-cli/src/transformers/program.ts
+++ b/packages/compiler-cli/src/transformers/program.ts
@@ -69,7 +69,7 @@ const MAX_FILE_COUNT_FOR_SINGLE_FILE_EMIT = 20;
 /**
  * Fields to lower within metadata in render2 mode.
  */
-const LOWER_FIELDS = ['useValue', 'useFactory', 'data', 'id'];
+const LOWER_FIELDS = ['useValue', 'useFactory', 'data', 'id', 'loadChildren'];
 
 /**
  * Fields to lower within metadata in render3 mode.
diff --git a/packages/compiler-cli/test/BUILD.bazel b/packages/compiler-cli/test/BUILD.bazel
index a6c0b2d355..e6cb2ebf07 100644
--- a/packages/compiler-cli/test/BUILD.bazel
+++ b/packages/compiler-cli/test/BUILD.bazel
@@ -69,6 +69,7 @@ jasmine_node_test(
         "//packages/common:npm_package",
         "//packages/core:npm_package",
         "//packages/platform-browser:npm_package",
+        "//packages/router:npm_package",
     ],
     deps = [
         ":ngc_lib",
diff --git a/packages/compiler-cli/test/ngc_spec.ts b/packages/compiler-cli/test/ngc_spec.ts
index 779ca766c7..259ea65783 100644
--- a/packages/compiler-cli/test/ngc_spec.ts
+++ b/packages/compiler-cli/test/ngc_spec.ts
@@ -869,6 +869,40 @@ describe('ngc transformer command-line', () => {
         expect(mymoduleSource).toMatch(/ɵ0 = .*'test'/);
       });
 
+      it('should lower loadChildren', () => {
+        write('mymodule.ts', `
+          import {Component, NgModule} from '@angular/core';
+          import {RouterModule} from '@angular/router';
+          
+          export function foo(): string {
+            console.log('side-effect');
+            return 'test';
+          }
+
+          @Component({
+            selector: 'route',
+            template: 'route',
+          })
+          export class Route {}
+
+          @NgModule({
+            declarations: [Route],
+            imports: [
+              RouterModule.forRoot([
+                {path: '', pathMatch: 'full', component: Route, loadChildren: foo()}
+              ]),
+            ]
+          })
+          export class MyModule {}
+        `);
+        expect(compile()).toEqual(0);
+
+        const mymodulejs = path.resolve(outDir, 'mymodule.js');
+        const mymoduleSource = fs.readFileSync(mymodulejs, 'utf8');
+        expect(mymoduleSource).toContain('loadChildren: ɵ0');
+        expect(mymoduleSource).toMatch(/ɵ0 = .*foo\(\)/);
+      });
+
       it('should be able to lower supported expressions', () => {
         writeConfig(`{
           "extends": "./tsconfig-base.json",
diff --git a/packages/compiler/src/aot/static_reflector.ts b/packages/compiler/src/aot/static_reflector.ts
index 812e54ac83..d8dd289192 100644
--- a/packages/compiler/src/aot/static_reflector.ts
+++ b/packages/compiler/src/aot/static_reflector.ts
@@ -28,7 +28,7 @@ const IGNORE = {
 
 const USE_VALUE = 'useValue';
 const PROVIDE = 'provide';
-const REFERENCE_SET = new Set([USE_VALUE, 'useFactory', 'data', 'id']);
+const REFERENCE_SET = new Set([USE_VALUE, 'useFactory', 'data', 'id', 'loadChildren']);
 const TYPEGUARD_POSTFIX = 'TypeGuard';
 const USE_IF = 'UseIf';