title: Angular 8 to 9 upgrade warnings when building
body: <p>I have an angular project that has multiple applications (app, dev, etc.) and I have recently upgraded it from Angular v8.2.3 to 9, and have now started to get many of the follwing warnings (about different components, this is just one example)</p>
  
  <pre><code>WARNING in {PATH_TO_PROJECT}\src\modules\dev\create-member\create-member.component.ts is part of the TypeScript compilation but it's unused.
  Add only entry points to the 'files' or 'include' properties in your tsconfig.
  </code></pre>
  
  <p>root ts config:</p>
  
  <pre><code>{
      "compileOnSave": false,
      "compilerOptions": {
          "allowJs": true,
          "outDir": "./dist/out-tsc",
          "sourceMap": true,
          "declaration": false,
          "moduleResolution": "node",
          "emitDecoratorMetadata": true,
          "experimentalDecorators": true,
          // tslint bug isn't checking for no unused imports, their solution is to add this
          // https://github.com/Microsoft/vscode-tslint/issues/70#issuecomment-241041929
          "noUnusedLocals": true,
          "noUnusedParameters": true,
          "target": "es2015",
          "typeRoots": [
              "node_modules/@types"
          ],
          "lib": [
              "es2018",
              "dom"
          ],
          "plugins": [
              {"name": "@angular/language-service"}
          ]
      }
  }
  </code></pre>
  
  <p>/src tsconfig:</p>
  
  <pre><code>{
      "extends": "../tsconfig.json",
      "compilerOptions": {
        "outDir": "../out-tsc/app",
        "baseUrl": "./",
        "module": "es2015",
        "types": []
      }
  }
  </code></pre>
  
  <p>I did manage to get everything to work without these warnings by adding a separate tsconfig under each application with the following contents:</p>
  
  <pre><code>{
      "extends": "../../tsconfig.json",
      "files": [
          "./{APP_NAME}.main.ts",
          "../../polyfills.ts"
      ]
  }
  </code></pre>
  
  <p>Everything seemed to be building just fine with ng build --project app but when I add the --prod flag, I get a bunch of template errors about components not being recognized
  E.g.</p>
  
  <pre><code>ERROR in src/modules/app/organizations/organization-data-budget-change/organization-data-budget-change.component.html:4:7 - error NG8002: Can't bind to 'formGroup' since it isn't a known property of 'form'.
  [1]
  [1] 4 &lt;form [formGroup]="DataBudgetChangeForm" class="card-body" novalidate&gt;
  [1]         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  [1]
  [1]   src/modules/app/organizations/organization-data-budget-change/organization-data-budget-change.component.ts:11:15
  [1]     11  templateUrl: 'organization-data-budget-change.component.html'
  [1]                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  [1]     Error occurs in the template of component OrganizationDataBudgetChangeComponent.
  </code></pre>
  
  <p>Essentially i'm just trying to get rid of the warnings mentioned above, and i'm not sure if this is an angular issue or if my config is incorrect</p>
  
  <p>UPDATE:
  It seems that with the tsconfig additions mentioned above, setting aot to false in my angular.json file causes everything to work normally (Not really a fix as I do still want to use aot going forward). Same thing for disabling ivy</p>