bmc-tpl-code-all-around/src/providers/actions/TabFix.ts

import * as vscode from 'vscode';

export class TabFix {
    public diagnosticCode = 'invalid_tab';

    public provideFix(document: vscode.TextDocument, diagnostic: vscode.Diagnostic): vscode.CodeAction[] {
        const action = new vscode.CodeAction("Convert tabs to 4 spaces", vscode.CodeActionKind.QuickFix);
        action.edit = new vscode.WorkspaceEdit();
        
        const line = document.lineAt(diagnostic.range.start.line);
        const newText = line.text.replace(/\t/g, '    ');
        
        action.edit.replace(document.uri, line.range, newText);
        action.diagnostics = [diagnostic];
        action.isPreferred = true;
        
        return [action];
    }
}