From c4bf21b9cb26c8936bf51636ac14cabf2cc44fe6 Mon Sep 17 00:00:00 2001
From: Andy <anhans@microsoft.com>
Date: Mon, 6 Nov 2017 10:59:39 -0800
Subject: [PATCH] Improvements to checkUnusedIdentifiers (#19607)

---
 src/compiler/checker.ts | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 532eee363d7..eb5442a7996 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -20430,21 +20430,20 @@ namespace ts {
                         case SyntaxKind.MethodSignature:
                         case SyntaxKind.CallSignature:
                         case SyntaxKind.ConstructSignature:
-                        case SyntaxKind.IndexSignature:
                         case SyntaxKind.FunctionType:
                         case SyntaxKind.ConstructorType:
-                            checkUnusedTypeParameters(<FunctionLikeDeclaration>node);
-                            break;
                         case SyntaxKind.TypeAliasDeclaration:
-                            checkUnusedTypeParameters(<TypeAliasDeclaration>node);
+                            checkUnusedTypeParameters(<MethodSignature | CallSignatureDeclaration | ConstructSignatureDeclaration | FunctionTypeNode | ConstructorTypeNode | TypeAliasDeclaration>node);
                             break;
+                        default:
+                            Debug.fail("Node should not have been registered for unused identifiers check");
                     }
                 }
             }
         }
 
         function checkUnusedLocalsAndParameters(node: Node): void {
-            if (node.parent.kind !== SyntaxKind.InterfaceDeclaration && noUnusedIdentifiers && !(node.flags & NodeFlags.Ambient)) {
+            if (noUnusedIdentifiers && !(node.flags & NodeFlags.Ambient)) {
                 node.locals.forEach(local => {
                     if (!local.isReferenced) {
                         if (local.valueDeclaration && getRootDeclaration(local.valueDeclaration).kind === SyntaxKind.Parameter) {