From 4b70a4e905b7a38b64f235412150cafd30d9559e Mon Sep 17 00:00:00 2001
From: Pete Bacon Darwin <pete@bacondarwin.com>
Date: Tue, 11 Dec 2018 12:14:21 +0000
Subject: [PATCH] feat(ivy): support NgModule metadata from calls that do not
 return ModuleWithProviders types (#27326)

Normally functions that return `ModuleWithProvider` objects should parameterize
the return type to include the type of `NgModule` that is being returned. For
example `forRoot(): ModuleWithProviders<RouterModule>`.

But in some cases, especially those generated by nccc, these functions to not
explicitly declare `ModuleWithProviders` as their return type. Instead they
return a "intersection" type, one of whose members is a type literal that
declares the `NgModule` type returned. For example:
`forRoot(): CustomType&{ngModule:RouterModule}`.

This commit changes the `NgModuleDecoratorHandler` so that it can extract
the `NgModule` type from either kind of declaration.

PR Close #27326
---
 .../src/ngtsc/annotations/src/ng_module.ts    | 41 ++++++++++++++++++-
 .../compiler-cli/test/ngtsc/ngtsc_spec.ts     | 33 +++++++++++++++
 2 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/packages/compiler-cli/src/ngtsc/annotations/src/ng_module.ts b/packages/compiler-cli/src/ngtsc/annotations/src/ng_module.ts
index a19261665d..54cb3a65cb 100644
--- a/packages/compiler-cli/src/ngtsc/annotations/src/ng_module.ts
+++ b/packages/compiler-cli/src/ngtsc/annotations/src/ng_module.ts
@@ -197,9 +197,20 @@ export class NgModuleDecoratorHandler implements DecoratorHandler<NgModuleAnalys
    */
   private _extractModuleFromModuleWithProvidersFn(node: ts.FunctionDeclaration|
                                                   ts.MethodDeclaration): ts.Expression|null {
-    const type = node.type;
+    const type = node.type || null;
+    return type &&
+        (this._reflectModuleFromTypeParam(type) || this._reflectModuleFromLiteralType(type));
+  }
+
+  /**
+   * Retrieve an `NgModule` identifier (T) from the specified `type`, if it is of the form:
+   * `ModuleWithProviders<T>`
+   * @param type The type to reflect on.
+   * @returns the identifier of the NgModule type if found, or null otherwise.
+   */
+  private _reflectModuleFromTypeParam(type: ts.TypeNode): ts.Expression|null {
     // Examine the type of the function to see if it's a ModuleWithProviders reference.
-    if (type === undefined || !ts.isTypeReferenceNode(type) || !ts.isIdentifier(type.typeName)) {
+    if (!ts.isTypeReferenceNode(type) || !ts.isIdentifier(type.typeName)) {
       return null;
     }
 
@@ -226,6 +237,32 @@ export class NgModuleDecoratorHandler implements DecoratorHandler<NgModuleAnalys
     return typeNodeToValueExpr(arg);
   }
 
+  /**
+   * Retrieve an `NgModule` identifier (T) from the specified `type`, if it is of the form:
+   * `A|B|{ngModule: T}|C`.
+   * @param type The type to reflect on.
+   * @returns the identifier of the NgModule type if found, or null otherwise.
+   */
+  private _reflectModuleFromLiteralType(type: ts.TypeNode): ts.Expression|null {
+    if (!ts.isIntersectionTypeNode(type)) {
+      return null;
+    }
+    for (const t of type.types) {
+      if (ts.isTypeLiteralNode(t)) {
+        for (const m of t.members) {
+          const ngModuleType = ts.isPropertySignature(m) && ts.isIdentifier(m.name) &&
+                  m.name.text === 'ngModule' && m.type ||
+              null;
+          const ngModuleExpression = ngModuleType && typeNodeToValueExpr(ngModuleType);
+          if (ngModuleExpression) {
+            return ngModuleExpression;
+          }
+        }
+      }
+    }
+    return null;
+  }
+
   /**
    * Compute a list of `Reference`s from a resolved metadata value.
    */
diff --git a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
index 22313073dd..93677ad278 100644
--- a/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
+++ b/packages/compiler-cli/test/ngtsc/ngtsc_spec.ts
@@ -441,6 +441,39 @@ describe('ngtsc behavioral tests', () => {
     });
   });
 
+  it('should unwrap a ModuleWithProviders-like function if a matching literal type is provided for it',
+     () => {
+       env.tsconfig();
+       env.write(`test.ts`, `
+        import {NgModule} from '@angular/core';
+        import {RouterModule} from 'router';
+
+        @NgModule({imports: [RouterModule.forRoot()]})
+        export class TestModule {}
+    `);
+
+       env.write('node_modules/router/index.d.ts', `
+        import {ModuleWithProviders} from '@angular/core';
+
+        export interface MyType extends ModuleWithProviders {}
+
+        declare class RouterModule {
+          static forRoot(): (MyType)&{ngModule:RouterModule};
+        }
+    `);
+
+       env.driveMain();
+
+       const jsContents = env.getContents('test.js');
+       expect(jsContents).toContain('imports: [[RouterModule.forRoot()]]');
+
+       const dtsContents = env.getContents('test.d.ts');
+       expect(dtsContents).toContain(`import * as i1 from 'router';`);
+       expect(dtsContents)
+           .toContain(
+               'i0.ɵNgModuleDefWithMeta<TestModule, never, [typeof i1.RouterModule], never>');
+     });
+
   it('should inject special types according to the metadata', () => {
     env.tsconfig();
     env.write(`test.ts`, `