fix(input): floating label not reacting when patching the value witho…

…ut emitting an event

Fixes the input's floating label state not being updated when the consumer patches the form control's value without emitting an event.

Fixes #8982.

src/lib/input/input.spec.ts

@@ -1130,6 +1130,21 @@ describe('MatInput with forms', () => {
     expect(el).not.toBeNull();
     expect(el.classList.contains('mat-form-field-empty')).toBe(false);
   }));
+
+  it('should update when the form field value is patched without emitting', fakeAsync(() => {
+    const fixture = TestBed.createComponent(MatInputWithFormControl);
+    fixture.detectChanges();
+
+    const el = fixture.debugElement.query(By.css('label')).nativeElement;
+
+    expect(el.classList).toContain('mat-form-field-empty');
+
+    fixture.componentInstance.formControl.patchValue('value', {emitEvent: false});
+    fixture.detectChanges();
+
+    expect(el.classList).not.toContain('mat-form-field-empty');
+  }));
+
 });
 
 @Component({
@@ -1183,7 +1198,10 @@ class MatInputPlaceholderElementTestComponent {
 }
 
 @Component({
-  template: `<mat-form-field><input matInput [formControl]="formControl"></mat-form-field>`
+  template: `
+    <mat-form-field>
+      <input matInput placeholder="Hello" [formControl]="formControl">
+    </mat-form-field>`
 })
 class MatInputWithFormControl {
   formControl = new FormControl();

src/lib/input/input.ts

@@ -224,11 +224,12 @@ export class MatInput extends _MatInputMixinBase implements MatFormFieldControl<
       // error triggers that we can't subscribe to (e.g. parent form submissions). This means
       // that whatever logic is in here has to be super lean or we risk destroying the performance.
       this.updateErrorState();
-    } else {
-      // When the input isn't used together with `@angular/forms`, we need to check manually for
-      // changes to the native `value` property in order to update the floating label.
-      this._dirtyCheckNativeValue();
     }
+
+    // We need to dirty-check the native element's value, because there are some cases where
+    // we won't be notified when it changes (e.g. the consumer isn't using forms or they're
+    // updating the value using `emitEvent: false`).
+    this._dirtyCheckNativeValue();
   }
 
   focus() { this._elementRef.nativeElement.focus(); }