fix(@ngtools/webpack): find aliased lazy route factories

Fix angular#14707

Author: filipesilva

src/transformers/import_factory.ts

@@ -10,6 +10,9 @@ import * as ts from 'typescript';
 import { forwardSlashPath } from '../utils';
 
 
+// Check if a ts.Symbol is an alias.
+const isAlias = (symbol: ts.Symbol) => symbol.flags & ts.SymbolFlags.Alias;
+
 /**
  * Given this original source code:
  *
@@ -193,15 +196,26 @@ function replaceImport(
 
   // Try to resolve the import. It might be a reexport from somewhere and the ngfactory will only
   // be present next to the original module.
-  const exportedSymbol = typeChecker.getSymbolAtLocation(exportNameId);
+  let exportedSymbol = typeChecker.getSymbolAtLocation(exportNameId);
   if (!exportedSymbol) {
     return warnAndBail();
   }
+  // Named exports are also a declaration in the re-exporting module so we have to follow the
+  // re-exports to find the original symbol.
+  if (isAlias(exportedSymbol)) {
+    exportedSymbol = typeChecker.getAliasedSymbol(exportedSymbol);
+    if (!exportedSymbol) {
+      return warnAndBail();
+    }
+  }
+
+  // Find declarations of the original symbol so we can get their source file name.
   const exportedSymbolDecl = exportedSymbol.getDeclarations();
   if (!exportedSymbolDecl || exportedSymbolDecl.length === 0) {
     return warnAndBail();
   }
 
+  // Let's guess the first declaration is the one we want, because we don't have a better criteria.
   // Get the relative path from the containing module to the imported module.
   const relativePath = relative(dirname(fileName), exportedSymbolDecl[0].getSourceFile().fileName);
 

src/transformers/import_factory_spec.ts

@@ -64,7 +64,7 @@ describe('@ngtools/webpack transformers', () => {
       expect(warningCalled).toBeTruthy();
     });
 
-    it('should support resolving reexports', () => {
+    it('should support resolving * re-exports', () => {
       const additionalFiles: Record<string, string> = {
         'shared/index.ts': `
           export * from './path/to/lazy/lazy.module';
@@ -95,5 +95,79 @@ describe('@ngtools/webpack transformers', () => {
 
       expect(tags.oneLine`${result}`).toEqual(tags.oneLine`${output}`);
     });
+
+    it('should support resolving named re-exports', () => {
+      const additionalFiles: Record<string, string> = {
+        'shared/index.ts': `
+          export { LazyModule } from './path/to/lazy/lazy.module';
+        `,
+        'shared/path/to/lazy/lazy.module.ts': `
+          export const LazyModule = {};
+        `,
+      };
+      const input = tags.stripIndent`
+        const ɵ0 = () => import('./shared').then(m => m.LazyModule);
+        const routes = [{
+          path: 'lazy',
+          loadChildren: ɵ0
+        }];
+      `;
+
+      const output = tags.stripIndent`
+        const ɵ0 = () => import("./shared/path/to/lazy/lazy.module.ngfactory").then(m => m.LazyModuleNgFactory);
+        const routes = [{
+          path: 'lazy',
+          loadChildren: ɵ0
+        }];
+      `;
+
+      const { program, compilerHost } = createTypescriptContext(input, additionalFiles, true);
+      const transformer = importFactory(() => { }, () => program.getTypeChecker());
+      const result = transformTypescript(undefined, [transformer], program, compilerHost);
+
+      expect(tags.oneLine`${result}`).toEqual(tags.oneLine`${output}`);
+    });
+
+
+    it('should support resolving re-export chains', () => {
+      const additionalFiles: Record<string, string> = {
+        'shared/index.ts': `
+          export { LazyModule } from './index2';
+        `,
+        'shared/index2.ts': `
+          export * from './index3';
+        `,
+        'shared/index3.ts': `
+          export { LazyModule } from './index4';
+        `,
+        'shared/index4.ts': `
+          export * from './path/to/lazy/lazy.module';
+        `,
+        'shared/path/to/lazy/lazy.module.ts': `
+          export const LazyModule = {};
+        `,
+      };
+      const input = tags.stripIndent`
+        const ɵ0 = () => import('./shared').then(m => m.LazyModule);
+        const routes = [{
+          path: 'lazy',
+          loadChildren: ɵ0
+        }];
+      `;
+
+      const output = tags.stripIndent`
+        const ɵ0 = () => import("./shared/path/to/lazy/lazy.module.ngfactory").then(m => m.LazyModuleNgFactory);
+        const routes = [{
+          path: 'lazy',
+          loadChildren: ɵ0
+        }];
+      `;
+
+      const { program, compilerHost } = createTypescriptContext(input, additionalFiles, true);
+      const transformer = importFactory(() => { }, () => program.getTypeChecker());
+      const result = transformTypescript(undefined, [transformer], program, compilerHost);
+
+      expect(tags.oneLine`${result}`).toEqual(tags.oneLine`${output}`);
+    });
   });
 });