Add code fix to remove unused label (#24037)

* Add code fix to remove unused label

* Test with trivia and fix indentation with dedented label

src/services/codefixes/fixUnusedLabel.ts

@@ -0,0 +1,25 @@
+/* @internal */
+namespace ts.codefix {
+    const fixId = "fixUnusedLabel";
+    const errorCodes = [Diagnostics.Unused_label.code];
+    registerCodeFix({
+        errorCodes,
+        getCodeActions(context) {
+            const changes = textChanges.ChangeTracker.with(context, t => doChange(t, context.sourceFile, context.span.start));
+            return [createCodeFixAction(fixId, changes, Diagnostics.Remove_unused_label, fixId, Diagnostics.Remove_all_unused_labels)];
+        },
+        fixIds: [fixId],
+        getAllCodeActions: context => codeFixAll(context, errorCodes, (changes, diag) => doChange(changes, diag.file, diag.start)),
+    });
+
+    function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, start: number): void {
+        const token = getTokenAtPosition(sourceFile, start, /*includeJsDocComment*/ false);
+        const labeledStatement = cast(token.parent, isLabeledStatement);
+        const pos = token.getStart(sourceFile);
+        const statementPos = labeledStatement.statement.getStart(sourceFile);
+        // If label is on a separate line, just delete the rest of that line, but not the indentation of the labeled statement.
+        const end = positionsAreOnSameLine(pos, statementPos, sourceFile) ? statementPos
+            : skipTrivia(sourceFile.text, findChildOfKind(labeledStatement, SyntaxKind.ColonToken, sourceFile)!.end, /*stopAfterLineBreak*/ true);
+        changes.deleteRange(sourceFile, { pos, end });
+    }
+}

src/services/tsconfig.json

@@ -99,6 +99,7 @@
         "codefixes/fixForgottenThisPropertyAccess.ts",
         "codefixes/fixUnusedIdentifier.ts",
         "codefixes/fixUnreachableCode.ts",
+        "codefixes/fixUnusedLabel.ts",
         "codefixes/fixJSDocTypes.ts",
         "codefixes/fixAwaitInSyncFunction.ts",
         "codefixes/disableJsDiagnostics.ts",