From 947d3e84d1c032a4f11a5c83a36e34b6bd5f45b1 Mon Sep 17 00:00:00 2001
From: Marcelo Luz <marcelopluz@gmail.com>
Date: Fri, 29 Sep 2017 16:15:02 -0400
Subject: [PATCH] fix(select) aria-labelledby (#7022)

aria-labelledby must not be in the DOM if it is empty
this causes accessability bugs.
---
 src/lib/select/select.spec.ts | 9 +++++++++
 src/lib/select/select.ts      | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/lib/select/select.spec.ts b/src/lib/select/select.spec.ts
index 8a8bb96260d..93fafbcc1d1 100644
--- a/src/lib/select/select.spec.ts
+++ b/src/lib/select/select.spec.ts
@@ -1802,6 +1802,15 @@ describe('MatSelect', () => {
         expect(select.getAttribute('aria-labelledby')).toBe('myLabelId');
       });
 
+      it('should not have aria-labelledby in the DOM if it`s not specified', async(() => {
+
+        fixture.detectChanges();
+
+        fixture.whenStable().then(() => {
+          expect(select.hasAttribute('aria-labelledby')).toBeFalsy();
+        });
+      }));
+
       it('should set the tabindex of the select to 0 by default', () => {
         expect(select.getAttribute('tabindex')).toEqual('0');
       });
diff --git a/src/lib/select/select.ts b/src/lib/select/select.ts
index 8a5f3d46259..1a5038a9b5f 100644
--- a/src/lib/select/select.ts
+++ b/src/lib/select/select.ts
@@ -371,7 +371,7 @@ export class MatSelect extends _MatSelectMixinBase implements AfterContentInit,
   @Input('aria-label') ariaLabel: string = '';
 
   /** Input that can be used to specify the `aria-labelledby` attribute. */
-  @Input('aria-labelledby') ariaLabelledby: string = '';
+  @Input('aria-labelledby') ariaLabelledby: string;
 
   /** Unique id of the element. */
   @Input()