Make FormatContext.host optional since it’s not necessary if format options are all applied

src/services/formatting/formatting.ts

@@ -3,7 +3,7 @@ namespace ts.formatting {
     export interface FormatContext {
         readonly options: FormatCodeSettings;
         readonly getRules: RulesMap;
-        readonly host: FormattingHost;
+        readonly host?: FormattingHost;
     }
 
     export interface TextRangeWithKind<T extends SyntaxKind = SyntaxKind> extends TextRange {

src/services/types.ts

@@ -203,6 +203,7 @@ namespace ts {
         has(dependencyName: string, inGroups?: PackageJsonDependencyGroup): boolean;
     }
 
+    /** @internal */
     export interface FormattingHost {
         getNewLine?(): string;
     }
@@ -210,8 +211,9 @@ namespace ts {
     //
     // Public interface of the host of a language service instance.
     //
-    export interface LanguageServiceHost extends GetEffectiveTypeRootsHost, FormattingHost {
+    export interface LanguageServiceHost extends GetEffectiveTypeRootsHost {
         getCompilationSettings(): CompilerOptions;
+        getNewLine?(): string;
         getProjectVersion?(): string;
         getScriptFileNames(): string[];
         getScriptKind?(fileName: string): ScriptKind;

src/services/utilities.ts

@@ -2085,9 +2085,9 @@ namespace ts {
     /**
      * The default is CRLF.
      */
-    export function getNewLineOrDefaultFromHost(host: FormattingHost, formatSettings?: FormatCodeSettings) {
-        return (formatSettings && formatSettings.newLineCharacter) ||
-            (host.getNewLine && host.getNewLine()) ||
+    export function getNewLineOrDefaultFromHost(host: FormattingHost | undefined, formatSettings?: FormatCodeSettings) {
+        return formatSettings?.newLineCharacter ||
+            host?.getNewLine?.() ||
             carriageReturnLineFeed;
     }