Angular Error: 'Component 'X' is not included in a module...' when declared in a sub module

Question

I'm trying to consolidate my dialogs into an Angular module, but I'm getting a linting error in the IDE:

Component 'X' is not included in a module and will not be available inside a template. Consider adding it to an NgModule declaration.

Despite this error the application still loads and runs successfully.

Example Component Definition

import { Component, Inject, OnInit, ViewEncapsulation } from '@angular/core';
import { MAT_DIALOG_DATA, MatDialogRef } from '@angular/material';

export interface AlertDialogData {
  titleText: string;
  dismissalText: string;
  contentComponent: string;
}

@Component({
  selector: 'app-alert-dialog',
  templateUrl: './alert-dialog.component.html',
  styleUrls: ['./alert-dialog.component.scss'],
  encapsulation: ViewEncapsulation.None
})
export class AlertDialogComponent implements OnInit {

  constructor(private dialogRef: MatDialogRef<AlertDialogComponent>, @Inject(MAT_DIALOG_DATA) public data: any) { }

  ngOnInit() {
  }

  handleCloseClick(): void {
    this.dialogRef.close();
  }

}

Sub module making Declaration/Export

import { CUSTOM_ELEMENTS_SCHEMA, NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { ZipLocatorDialogComponent } from './zip-locator-dialog/zip-locator-dialog.component';
import { AlertDialogComponent } from './alert-dialog/alert-dialog.component';
import { HelperDialogComponent } from './helper-dialog/helper-dialog.component';
import {
  MatAutocompleteModule, MatButtonModule, MatDialogModule, MatFormFieldModule, MatInputModule,
  MatSelectModule
} from '@angular/material';
import { FlexLayoutModule } from '@angular/flex-layout';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';

@NgModule({
  imports: [
    CommonModule,
    FlexLayoutModule,
    FormsModule,
    ReactiveFormsModule,
    MatDialogModule,
    MatInputModule,
    MatFormFieldModule,
    MatSelectModule,
    MatAutocompleteModule,
    MatButtonModule
  ],
  exports: [
    ZipLocatorDialogComponent,
    HelperDialogComponent,
    AlertDialogComponent
  ],
  declarations: [
    ZipLocatorDialogComponent,
    HelperDialogComponent,
    AlertDialogComponent
  ],
  entryComponents: [
    ZipLocatorDialogComponent,
    HelperDialogComponent,
    AlertDialogComponent
  ],
  schemas: [
    CUSTOM_ELEMENTS_SCHEMA
  ]
})
export class AppDialogsModule { }

App Module

// <editor-fold desc="Global Application Imports">
import { BrowserModule } from '@angular/platform-browser';
import { NgModule, CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HTTP_INTERCEPTORS, HttpClientModule } from '@angular/common/http';
import { RouterModule } from '@angular/router';
import { RouteDefinitions } from './app.routes';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { FlexLayoutModule } from '@angular/flex-layout';
import { WebWrapperModule } from 'web-wrapper';
import { UiComponentsModule } from './ui-components.module';
import { AppComponent } from './app.component';


// OPERATORS
import './rxjs-operators';

// SERVICES
import { LoginManagerService } from './services/login-manager.service';
import { UtilsService } from './services/utils.service';
import { DataManagerService } from './services/data-manager.service';
import { ReferenceDataManagerService } from './services/reference-data-manager.service';
import { InfrastructureApiService } from './services/infrastructure-api.service';
// </editor-fold>

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    FormsModule,
    FlexLayoutModule,
    HttpClientModule,
    WebWrapperModule,
    UiComponentsModule,
    AppDialogsModule,
    RouterModule.forRoot(RouteDefinitions)
  ],
  providers: [
    UtilsService,
    LoginManagerService,
    DataManagerService,
    InfrastructureApiService,
    ReferenceDataManagerService
  ],
  schemas: [
    CUSTOM_ELEMENTS_SCHEMA
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

Versions

Angular CLI: 1.5.0
Node: 7.2.1
OS: win32 x64
Angular: 4.4.6
... animations, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, router, tsc-wrapped

@angular/cdk: 2.0.0-beta.12
@angular/cli: 1.5.0
@angular/flex-layout: 2.0.0-beta.11-b01c2d7
@angular/material: 2.0.0-beta.12
@angular-devkit/build-optimizer: 0.0.32
@angular-devkit/core: 0.0.20
@angular-devkit/schematics: 0.0.35
@ngtools/json-schema: 1.1.0
@ngtools/webpack: 1.8.0
@schematics/angular: 0.1.2
typescript: 2.4.2
webpack: 3.8.1

Answer 1

I had this same issue and this is how it got resolved :

1) Goto Intellij / IDE settings and tick(set) the Recompile on changes to :

2) Goto tsconfig.json and set the compileOnSave to true :

Now go and remove the @Component that's causing the issue, and retype @Component.

This worked for me :) Good Luck.