Fix writing new nodes, update protocol

src/server/protocol.ts

@@ -2946,6 +2946,12 @@ namespace ts.server.protocol {
         Smart = "Smart",
     }
 
+    export enum SemicolonPreference {
+        Ignore = "ignore",
+        Insert = "insert",
+        Remove = "remove",
+    }
+
     export interface EditorSettings {
         baseIndentSize?: number;
         indentSize?: number;
@@ -2972,6 +2978,7 @@ namespace ts.server.protocol {
         placeOpenBraceOnNewLineForFunctions?: boolean;
         placeOpenBraceOnNewLineForControlBlocks?: boolean;
         insertSpaceBeforeTypeAnnotation?: boolean;
+        semicolonPreference?: SemicolonPreference
     }
 
     export interface UserPreferences {

src/services/formatting/formatting.ts

@@ -426,7 +426,7 @@ namespace ts.formatting {
             const leadingTrivia = formattingScanner.getCurrentLeadingTrivia();
             if (leadingTrivia) {
                 indentTriviaItems(leadingTrivia, initialIndentation, /*indentNextTokenOrTrivia*/ false,
-                                  item => processRange(item, sourceFile.getLineAndCharacterOfPosition(item.pos), enclosingNode, enclosingNode, /*dynamicIndentation*/ undefined!));
+                    item => processRange(item, sourceFile.getLineAndCharacterOfPosition(item.pos), enclosingNode, enclosingNode, /*dynamicIndentation*/ undefined!));
                 trimTrailingWhitespacesForRemainingRange();
             }
         }
@@ -477,7 +477,7 @@ namespace ts.formatting {
             parent: Node,
             parentDynamicIndentation: DynamicIndentation,
             effectiveParentStartLine: number
-        ): { indentation: number, delta: number } {
+        ): { indentation: number, delta: number; } {
             const delta = SmartIndenter.shouldIndentChildNode(options, node) ? options.indentSize! : 0;
 
             if (effectiveParentStartLine === startLine) {
@@ -867,7 +867,7 @@ namespace ts.formatting {
                     if (currentTokenInfo.leadingTrivia) {
                         const commentIndentation = dynamicIndentation.getIndentationForComment(currentTokenInfo.token.kind, tokenIndentation, container);
                         indentNextTokenOrTrivia = indentTriviaItems(currentTokenInfo.leadingTrivia, commentIndentation, indentNextTokenOrTrivia,
-                                                                    item => insertIndentation(item.pos, commentIndentation, /*lineAdded*/ false));
+                            item => insertIndentation(item.pos, commentIndentation, /*lineAdded*/ false));
                     }
 
                     // indent token only if is it is in target range and does not overlap with any error ranges
@@ -1317,7 +1317,7 @@ namespace ts.formatting {
         return SyntaxKind.Unknown;
     }
 
-    let internedSizes: { tabSize: number; indentSize: number };
+    let internedSizes: { tabSize: number; indentSize: number; };
     let internedTabsIndentation: string[] | undefined;
     let internedSpacesIndentation: string[] | undefined;
 

src/services/textChanges.ts

@@ -835,10 +835,12 @@ namespace ts.textChanges {
         function getFormatCodeSettingsForWriting(context: formatting.FormatContext, sourceFile: SourceFile): FormatCodeSettings {
             return {
                 ...context.options,
-                // If the user has no semicolon preference defined, try to match whatever’s in the source file
-                semicolonPreference: !context.options.semicolonPreference || context.options.semicolonPreference === SemicolonPreference.Ignore
-                    ? probablyUsesSemicolons(sourceFile) ? SemicolonPreference.Ignore : SemicolonPreference.Remove
-                    : context.options.semicolonPreference,
+                // If the user has no semicolon preference defined and the file doesn’t use semicolons,
+                // make the formatter remove them. Otherwise, ignore semicolons in the formatter because
+                // the writer will insert them by default.
+                semicolonPreference: context.options.semicolonPreference === SemicolonPreference.Remove || (!context.options.semicolonPreference || context.options.semicolonPreference === SemicolonPreference.Ignore) && !probablyUsesSemicolons(sourceFile)
+                    ? SemicolonPreference.Remove
+                    : SemicolonPreference.Ignore,
             };
         }