From ac7c2ba9e2f71edc03fdf3fd2f753d145584cc83 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Tue, 21 Aug 2018 16:18:51 -0700
Subject: [PATCH 1/2] Remove unused overloads of 'deduplicate' and
 'deduplicateSorted'

---
 src/compiler/core.ts | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 1eaab5b1b5..3cd8e1fd11 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -775,7 +775,7 @@ namespace ts {
         return deduplicated.map(i => array[i]);
     }
 
-    function deduplicateEquality<T>(array: ReadonlyArray<T>, equalityComparer: EqualityComparer<T>) {
+    function deduplicateEquality<T>(array: ReadonlyArray<T>, equalityComparer?: EqualityComparer<T>) {
         const result: T[] = [];
         for (const item of array) {
             pushIfUnique(result, item, equalityComparer);
@@ -789,23 +789,17 @@ namespace ts {
      * @param comparer An optional `Comparer` used to sort entries before comparison, though the
      * result will remain in the original order in `array`.
      */
-    export function deduplicate<T>(array: ReadonlyArray<T>, equalityComparer?: EqualityComparer<T>, comparer?: Comparer<T>): T[];
-    export function deduplicate<T>(array: ReadonlyArray<T> | undefined, equalityComparer?: EqualityComparer<T>, comparer?: Comparer<T>): T[] | undefined;
-    export function deduplicate<T>(array: ReadonlyArray<T> | undefined, equalityComparer: EqualityComparer<T>, comparer?: Comparer<T>): T[] | undefined {
-        return !array ? undefined :
-            array.length === 0 ? [] :
+    export function deduplicate<T>(array: ReadonlyArray<T>, equalityComparer?: EqualityComparer<T>, comparer?: Comparer<T>): T[] {
+        return array.length === 0 ? [] :
             array.length === 1 ? array.slice() :
-            comparer ? deduplicateRelational(array, equalityComparer, comparer) :
+            comparer ? deduplicateRelational(array, equalityComparer!, comparer) :
             deduplicateEquality(array, equalityComparer);
     }
 
     /**
      * Deduplicates an array that has already been sorted.
      */
-    function deduplicateSorted<T>(array: ReadonlyArray<T>, comparer: EqualityComparer<T> | Comparer<T>): T[];
-    function deduplicateSorted<T>(array: ReadonlyArray<T> | undefined, comparer: EqualityComparer<T> | Comparer<T>): T[] | undefined;
-    function deduplicateSorted<T>(array: ReadonlyArray<T> | undefined, comparer: EqualityComparer<T> | Comparer<T>): T[] | undefined {
-        if (!array) return undefined;
+    function deduplicateSorted<T>(array: ReadonlyArray<T>, comparer: EqualityComparer<T> | Comparer<T>): T[] {
         if (array.length === 0) return [];
 
         let last = array[0];

From 213d374e13b1b6916598d28c1373e050547def20 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Wed, 22 Aug 2018 15:27:03 -0700
Subject: [PATCH 2/2] Make equalityComparer non-optional

---
 src/compiler/core.ts  | 6 +++---
 src/server/session.ts | 7 +------
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 3cd8e1fd11..722b42975e 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -775,7 +775,7 @@ namespace ts {
         return deduplicated.map(i => array[i]);
     }
 
-    function deduplicateEquality<T>(array: ReadonlyArray<T>, equalityComparer?: EqualityComparer<T>) {
+    function deduplicateEquality<T>(array: ReadonlyArray<T>, equalityComparer: EqualityComparer<T>) {
         const result: T[] = [];
         for (const item of array) {
             pushIfUnique(result, item, equalityComparer);
@@ -789,10 +789,10 @@ namespace ts {
      * @param comparer An optional `Comparer` used to sort entries before comparison, though the
      * result will remain in the original order in `array`.
      */
-    export function deduplicate<T>(array: ReadonlyArray<T>, equalityComparer?: EqualityComparer<T>, comparer?: Comparer<T>): T[] {
+    export function deduplicate<T>(array: ReadonlyArray<T>, equalityComparer: EqualityComparer<T>, comparer?: Comparer<T>): T[] {
         return array.length === 0 ? [] :
             array.length === 1 ? array.slice() :
-            comparer ? deduplicateRelational(array, equalityComparer!, comparer) :
+            comparer ? deduplicateRelational(array, equalityComparer, comparer) :
             deduplicateEquality(array, equalityComparer);
     }
 
diff --git a/src/server/session.ts b/src/server/session.ts
index 8d2fbe9e19..43f2e4f76b 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -266,8 +266,6 @@ namespace ts.server {
         getValue: (path: Path) => T,
         projects: Projects,
         action: (project: Project, value: T) => ReadonlyArray<U> | U | undefined,
-        comparer?: (a: U, b: U) => number,
-        areEqual?: (a: U, b: U) => boolean,
     ): U[] {
         const outputs = flatMap(isArray(projects) ? projects : projects.projects, project => action(project, defaultValue));
         if (!isArray(projects) && projects.symLinkedProjects) {
@@ -276,10 +274,7 @@ namespace ts.server {
                 outputs.push(...flatMap(projects, project => action(project, value)));
             });
         }
-
-        return comparer
-            ? sortAndDeduplicate(outputs, comparer, areEqual)
-            : deduplicate(outputs, areEqual);
+        return deduplicate(outputs, equateValues);
     }
 
     function combineProjectOutputFromEveryProject<T>(projectService: ProjectService, action: (project: Project) => ReadonlyArray<T>, areEqual: (a: T, b: T) => boolean) {