fix(compiler): reexport less symbols in .ngfactory.ts files (#19884)

* don't reexport symbols that the user already reexported
* never reexport symbols that are part of arguments of non simple function calls

Fixes #19883

PR Close #19884

packages/compiler/test/aot/compiler_spec.ts

@@ -491,10 +491,11 @@ describe('compiler (unbundled Angular)', () => {
       const libInput: MockDirectory = {
         'lib': {
           'base.ts': `
+            export class AValue {}
             export type AType = {};
 
             export class AClass {
-              constructor(a: AType) {}
+              constructor(a: AType, b: AValue) {}
             }
           `
         }
@@ -502,7 +503,7 @@ describe('compiler (unbundled Angular)', () => {
       const appInput: MockDirectory = {
         'app': {
           'main.ts': `
-            export * from '../lib/base';
+            export {AClass} from '../lib/base';
           `
         }
       };
@@ -511,7 +512,105 @@ describe('compiler (unbundled Angular)', () => {
       const {genFiles: appGenFiles} =
           compile([appInput, libOutDir, angularSummaryFiles], {useSummaries: true});
       const appNgFactory = appGenFiles.find((f) => f.genFileUrl === '/app/main.ngfactory.ts');
-      expect(toTypeScript(appNgFactory)).not.toContain('AType');
+      const appNgFactoryTs = toTypeScript(appNgFactory);
+      expect(appNgFactoryTs).not.toContain('AType');
+      expect(appNgFactoryTs).toContain('AValue');
+    });
+
+    it('should not reexport complex function calls', () => {
+      const libInput: MockDirectory = {
+        'lib': {
+          'base.ts': `
+            export class AClass {
+              constructor(arg: any) {}
+
+              static create(arg: any = null): AClass { return new AClass(arg); }
+
+              call(arg: any) {}
+            }
+
+            export function simple(arg: any) { return [arg]; }
+
+            export const ctor_arg = {};
+            export const ctor_call = new AClass(ctor_arg);
+
+            export const static_arg = {};
+            export const static_call = AClass.create(static_arg);
+
+            export const complex_arg = {};
+            export const complex_call = AClass.create().call(complex_arg);
+
+            export const simple_arg = {};
+            export const simple_call = simple(simple_arg);
+          `
+        }
+      };
+      const appInput: MockDirectory = {
+        'app': {
+          'main.ts': `
+            import {ctor_call, static_call, complex_call, simple_call} from '../lib/base';
+
+            export const calls = [ctor_call, static_call, complex_call, simple_call];
+          `,
+        }
+      };
+
+      const {outDir: libOutDir} = compile([libInput, angularSummaryFiles], {useSummaries: true});
+      const {genFiles: appGenFiles} =
+          compile([appInput, libOutDir, angularSummaryFiles], {useSummaries: true});
+      const appNgFactory = appGenFiles.find((f) => f.genFileUrl === '/app/main.ngfactory.ts');
+      const appNgFactoryTs = toTypeScript(appNgFactory);
+
+      // metadata of ctor calls is preserved, so we reexport the argument
+      expect(appNgFactoryTs).toContain('ctor_arg');
+      expect(appNgFactoryTs).toContain('ctor_call');
+
+      // metadata of static calls is preserved, so we reexport the argument
+      expect(appNgFactoryTs).toContain('static_arg');
+      expect(appNgFactoryTs).toContain('AClass');
+      expect(appNgFactoryTs).toContain('static_call');
+
+      // metadata of complex calls is elided, so we don't reexport the argument
+      expect(appNgFactoryTs).not.toContain('complex_arg');
+      expect(appNgFactoryTs).toContain('complex_call');
+
+      // metadata of simple calls is preserved, so we reexport the argument
+      expect(appNgFactoryTs).toContain('simple_arg');
+      expect(appNgFactoryTs).toContain('simple_call');
+    });
+
+    it('should not reexport already exported symbols except for lowered symbols', () => {
+      const libInput: MockDirectory = {
+        'lib': {
+          'base.ts': `
+            export const exportedVar = 1;
+
+            // A symbol introduced by lowering expressions
+            export const ɵ1 = 'lowered symbol';
+          `
+        }
+      };
+      const appInput: MockDirectory = {
+        'app': {
+          'main.ts': `export * from '../lib/base';`,
+        }
+      };
+
+      const {outDir: libOutDir} = compile([libInput, angularSummaryFiles], {useSummaries: true});
+      const {genFiles: appGenFiles} =
+          compile([appInput, libOutDir, angularSummaryFiles], {useSummaries: true});
+      const appNgFactory = appGenFiles.find((f) => f.genFileUrl === '/app/main.ngfactory.ts');
+      const appNgFactoryTs = toTypeScript(appNgFactory);
+
+      // we don't need to reexport exported symbols via the .ngfactory
+      // as we can refer to them via the reexport.
+      expect(appNgFactoryTs).not.toContain('exportedVar');
+
+      // although ɵ1 is reexported via `export *`, we still need to reexport it
+      // via the .ngfactory as tsickle expands `export *` into named exports,
+      // and doesn't know about our lowered symbols as we introduce them
+      // after the typecheck phase.
+      expect(appNgFactoryTs).toContain('ɵ1');
     });
   });