Make equalityComparer non-optional

Author: Andy Hanson

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);
     }
 

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) {