lldb/source/Commands/CommandObjectExpression.cpp

   1 //===-- CommandObjectExpression.cpp ---------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "CommandObjectExpression.h"
  10 #include "lldb/Core/Debugger.h"
  11 #include "lldb/Expression/ExpressionVariable.h"
  12 #include "lldb/Expression/REPL.h"
  13 #include "lldb/Expression/UserExpression.h"
  14 #include "lldb/Host/OptionParser.h"
  15 #include "lldb/Interpreter/CommandInterpreter.h"
  16 #include "lldb/Interpreter/CommandOptionArgumentTable.h"
  17 #include "lldb/Interpreter/CommandReturnObject.h"
  18 #include "lldb/Interpreter/OptionArgParser.h"
  19 #include "lldb/Target/Language.h"
  20 #include "lldb/Target/Process.h"
  21 #include "lldb/Target/StackFrame.h"
  22 #include "lldb/Target/Target.h"
  23 #include "lldb/Utility/DiagnosticsRendering.h"
  24 #include "lldb/lldb-enumerations.h"
  25 #include "lldb/lldb-private-enumerations.h"
  26
  27 using namespace lldb;
  28 using namespace lldb_private;
  29
  30 CommandObjectExpression::CommandOptions::CommandOptions() = default;
  31
  32 CommandObjectExpression::CommandOptions::~CommandOptions() = default;
  33
  34 #define LLDB_OPTIONS_expression
  35 #include "CommandOptions.inc"
  36
  37 Status CommandObjectExpression::CommandOptions::SetOptionValue(
  38     uint32_t option_idx, llvm::StringRef option_arg,
  39     ExecutionContext *execution_context) {
  40   Status error;
  41
  42   const int short_option = GetDefinitions()[option_idx].short_option;
  43
  44   switch (short_option) {
  45   case 'l':
  46     language = Language::GetLanguageTypeFromString(option_arg);
  47     if (language == eLanguageTypeUnknown) {
  48       StreamString sstr;
  49       sstr.Printf("unknown language type: '%s' for expression. "
  50                   "List of supported languages:\n",
  51                   option_arg.str().c_str());
  52
  53       Language::PrintSupportedLanguagesForExpressions(sstr, "  ", "\n");
  54       error = Status(sstr.GetString().str());
  55     }
  56     break;
  57
  58   case 'a': {
  59     bool success;
  60     bool result;
  61     result = OptionArgParser::ToBoolean(option_arg, true, &success);
  62     if (!success)
  63       error = Status::FromErrorStringWithFormat(
  64           "invalid all-threads value setting: \"%s\"",
  65           option_arg.str().c_str());
  66     else
  67       try_all_threads = result;
  68   } break;
  69
  70   case 'i': {
  71     bool success;
  72     bool tmp_value = OptionArgParser::ToBoolean(option_arg, true, &success);
  73     if (success)
  74       ignore_breakpoints = tmp_value;
  75     else
  76       error = Status::FromErrorStringWithFormat(
  77           "could not convert \"%s\" to a boolean value.",
  78           option_arg.str().c_str());
  79     break;
  80   }
  81
  82   case 'j': {
  83     bool success;
  84     bool tmp_value = OptionArgParser::ToBoolean(option_arg, true, &success);
  85     if (success)
  86       allow_jit = tmp_value;
  87     else
  88       error = Status::FromErrorStringWithFormat(
  89           "could not convert \"%s\" to a boolean value.",
  90           option_arg.str().c_str());
  91     break;
  92   }
  93
  94   case 't':
  95     if (option_arg.getAsInteger(0, timeout)) {
  96       timeout = 0;
  97       error = Status::FromErrorStringWithFormat(
  98           "invalid timeout setting \"%s\"", option_arg.str().c_str());
  99     }
 100     break;
 101
 102   case 'u': {
 103     bool success;
 104     bool tmp_value = OptionArgParser::ToBoolean(option_arg, true, &success);
 105     if (success)
 106       unwind_on_error = tmp_value;
 107     else
 108       error = Status::FromErrorStringWithFormat(
 109           "could not convert \"%s\" to a boolean value.",
 110           option_arg.str().c_str());
 111     break;
 112   }
 113
 114   case 'v':
 115     if (option_arg.empty()) {
 116       m_verbosity = eLanguageRuntimeDescriptionDisplayVerbosityFull;
 117       break;
 118     }
 119     m_verbosity = (LanguageRuntimeDescriptionDisplayVerbosity)
 120         OptionArgParser::ToOptionEnum(
 121             option_arg, GetDefinitions()[option_idx].enum_values, 0, error);
 122     if (!error.Success())
 123       error = Status::FromErrorStringWithFormat(
 124           "unrecognized value for description-verbosity '%s'",
 125           option_arg.str().c_str());
 126     break;
 127
 128   case 'g':
 129     debug = true;
 130     unwind_on_error = false;
 131     ignore_breakpoints = false;
 132     break;
 133
 134   case 'p':
 135     top_level = true;
 136     break;
 137
 138   case 'X': {
 139     bool success;
 140     bool tmp_value = OptionArgParser::ToBoolean(option_arg, true, &success);
 141     if (success)
 142       auto_apply_fixits = tmp_value ? eLazyBoolYes : eLazyBoolNo;
 143     else
 144       error = Status::FromErrorStringWithFormat(
 145           "could not convert \"%s\" to a boolean value.",
 146           option_arg.str().c_str());
 147     break;
 148   }
 149
 150   case '\x01': {
 151     bool success;
 152     bool persist_result =
 153         OptionArgParser::ToBoolean(option_arg, true, &success);
 154     if (success)
 155       suppress_persistent_result = !persist_result ? eLazyBoolYes : eLazyBoolNo;
 156     else
 157       error = Status::FromErrorStringWithFormat(
 158           "could not convert \"%s\" to a boolean value.",
 159           option_arg.str().c_str());
 160     break;
 161   }
 162
 163   default:
 164     llvm_unreachable("Unimplemented option");
 165   }
 166
 167   return error;
 168 }
 169
 170 void CommandObjectExpression::CommandOptions::OptionParsingStarting(
 171     ExecutionContext *execution_context) {
 172   auto process_sp =
 173       execution_context ? execution_context->GetProcessSP() : ProcessSP();
 174   if (process_sp) {
 175     ignore_breakpoints = process_sp->GetIgnoreBreakpointsInExpressions();
 176     unwind_on_error = process_sp->GetUnwindOnErrorInExpressions();
 177   } else {
 178     ignore_breakpoints = true;
 179     unwind_on_error = true;
 180   }
 181
 182   show_summary = true;
 183   try_all_threads = true;
 184   timeout = 0;
 185   debug = false;
 186   language = eLanguageTypeUnknown;
 187   m_verbosity = eLanguageRuntimeDescriptionDisplayVerbosityCompact;
 188   auto_apply_fixits = eLazyBoolCalculate;
 189   top_level = false;
 190   allow_jit = true;
 191   suppress_persistent_result = eLazyBoolCalculate;
 192 }
 193
 194 llvm::ArrayRef<OptionDefinition>
 195 CommandObjectExpression::CommandOptions::GetDefinitions() {
 196   return llvm::ArrayRef(g_expression_options);
 197 }
 198
 199 EvaluateExpressionOptions
 200 CommandObjectExpression::CommandOptions::GetEvaluateExpressionOptions(
 201     const Target &target, const OptionGroupValueObjectDisplay &display_opts) {
 202   EvaluateExpressionOptions options;
 203   options.SetCoerceToId(display_opts.use_objc);
 204   options.SetUnwindOnError(unwind_on_error);
 205   options.SetIgnoreBreakpoints(ignore_breakpoints);
 206   options.SetKeepInMemory(true);
 207   options.SetUseDynamic(display_opts.use_dynamic);
 208   options.SetTryAllThreads(try_all_threads);
 209   options.SetDebug(debug);
 210   options.SetLanguage(language);
 211   options.SetExecutionPolicy(
 212       allow_jit ? EvaluateExpressionOptions::default_execution_policy
 213                 : lldb_private::eExecutionPolicyNever);
 214
 215   bool auto_apply_fixits;
 216   if (this->auto_apply_fixits == eLazyBoolCalculate)
 217     auto_apply_fixits = target.GetEnableAutoApplyFixIts();
 218   else
 219     auto_apply_fixits = this->auto_apply_fixits == eLazyBoolYes;
 220
 221   options.SetAutoApplyFixIts(auto_apply_fixits);
 222   options.SetRetriesWithFixIts(target.GetNumberOfRetriesWithFixits());
 223
 224   if (top_level)
 225     options.SetExecutionPolicy(eExecutionPolicyTopLevel);
 226
 227   // If there is any chance we are going to stop and want to see what went
 228   // wrong with our expression, we should generate debug info
 229   if (!ignore_breakpoints || !unwind_on_error)
 230     options.SetGenerateDebugInfo(true);
 231
 232   if (timeout > 0)
 233     options.SetTimeout(std::chrono::microseconds(timeout));
 234   else
 235     options.SetTimeout(std::nullopt);
 236   return options;
 237 }
 238
 239 bool CommandObjectExpression::CommandOptions::ShouldSuppressResult(
 240     const OptionGroupValueObjectDisplay &display_opts) const {
 241   // Explicitly disabling persistent results takes precedence over the
 242   // m_verbosity/use_objc logic.
 243   if (suppress_persistent_result != eLazyBoolCalculate)
 244     return suppress_persistent_result == eLazyBoolYes;
 245
 246   return display_opts.use_objc &&
 247          m_verbosity == eLanguageRuntimeDescriptionDisplayVerbosityCompact;
 248 }
 249
 250 CommandObjectExpression::CommandObjectExpression(
 251     CommandInterpreter &interpreter)
 252     : CommandObjectRaw(interpreter, "expression",
 253                        "Evaluate an expression on the current "
 254                        "thread.  Displays any returned value "
 255                        "with LLDB's default formatting.",
 256                        "",
 257                        eCommandProcessMustBePaused | eCommandTryTargetAPILock),
 258       IOHandlerDelegate(IOHandlerDelegate::Completion::Expression),
 259       m_format_options(eFormatDefault),
 260       m_repl_option(LLDB_OPT_SET_1, false, "repl", 'r', "Drop into REPL", false,
 261                     true),
 262       m_expr_line_count(0) {
 263   SetHelpLong(
 264       R"(
 265 Single and multi-line expressions:
 266
 267 )"
 268       "    The expression provided on the command line must be a complete expression \
 269 with no newlines.  To evaluate a multi-line expression, \
 270 hit a return after an empty expression, and lldb will enter the multi-line expression editor. \
 271 Hit return on an empty line to end the multi-line expression."
 272
 273       R"(
 274
 275 Timeouts:
 276
 277 )"
 278       "    If the expression can be evaluated statically (without running code) then it will be.  \
 279 Otherwise, by default the expression will run on the current thread with a short timeout: \
 280 currently .25 seconds.  If it doesn't return in that time, the evaluation will be interrupted \
 281 and resumed with all threads running.  You can use the -a option to disable retrying on all \
 282 threads.  You can use the -t option to set a shorter timeout."
 283       R"(
 284
 285 User defined variables:
 286
 287 )"
 288       "    You can define your own variables for convenience or to be used in subsequent expressions.  \
 289 You define them the same way you would define variables in C.  If the first character of \
 290 your user defined variable is a $, then the variable's value will be available in future \
 291 expressions, otherwise it will just be available in the current expression."
 292       R"(
 293
 294 Continuing evaluation after a breakpoint:
 295
 296 )"
 297       "    If the \"-i false\" option is used, and execution is interrupted by a breakpoint hit, once \
 298 you are done with your investigation, you can either remove the expression execution frames \
 299 from the stack with \"thread return -x\" or if you are still interested in the expression result \
 300 you can issue the \"continue\" command and the expression evaluation will complete and the \
 301 expression result will be available using the \"thread.completed-expression\" key in the thread \
 302 format."
 303
 304       R"(
 305
 306 Examples:
 307
 308     expr my_struct->a = my_array[3]
 309     expr -f bin -- (index * 8) + 5
 310     expr unsigned int $foo = 5
 311     expr char c[] = \"foo\"; c[0])");
 312
 313   AddSimpleArgumentList(eArgTypeExpression);
 314
 315   // Add the "--format" and "--gdb-format"
 316   m_option_group.Append(&m_format_options,
 317                         OptionGroupFormat::OPTION_GROUP_FORMAT |
 318                             OptionGroupFormat::OPTION_GROUP_GDB_FMT,
 319                         LLDB_OPT_SET_1);
 320   m_option_group.Append(&m_command_options);
 321   m_option_group.Append(&m_varobj_options, LLDB_OPT_SET_ALL,
 322                         LLDB_OPT_SET_1 | LLDB_OPT_SET_2);
 323   m_option_group.Append(&m_repl_option, LLDB_OPT_SET_ALL, LLDB_OPT_SET_3);
 324   m_option_group.Finalize();
 325 }
 326
 327 CommandObjectExpression::~CommandObjectExpression() = default;
 328
 329 Options *CommandObjectExpression::GetOptions() { return &m_option_group; }
 330
 331 void CommandObjectExpression::HandleCompletion(CompletionRequest &request) {
 332   EvaluateExpressionOptions options;
 333   options.SetCoerceToId(m_varobj_options.use_objc);
 334   options.SetLanguage(m_command_options.language);
 335   options.SetExecutionPolicy(lldb_private::eExecutionPolicyNever);
 336   options.SetAutoApplyFixIts(false);
 337   options.SetGenerateDebugInfo(false);
 338
 339   ExecutionContext exe_ctx(m_interpreter.GetExecutionContext());
 340
 341   // Get out before we start doing things that expect a valid frame pointer.
 342   if (exe_ctx.GetFramePtr() == nullptr)
 343     return;
 344
 345   Target *exe_target = exe_ctx.GetTargetPtr();
 346   Target &target = exe_target ? *exe_target : GetDummyTarget();
 347
 348   unsigned cursor_pos = request.GetRawCursorPos();
 349   // Get the full user input including the suffix. The suffix is necessary
 350   // as OptionsWithRaw will use it to detect if the cursor is cursor is in the
 351   // argument part of in the raw input part of the arguments. If we cut of
 352   // of the suffix then "expr -arg[cursor] --" would interpret the "-arg" as
 353   // the raw input (as the "--" is hidden in the suffix).
 354   llvm::StringRef code = request.GetRawLineWithUnusedSuffix();
 355
 356   const std::size_t original_code_size = code.size();
 357
 358   // Remove the first token which is 'expr' or some alias/abbreviation of that.
 359   code = llvm::getToken(code).second.ltrim();
 360   OptionsWithRaw args(code);
 361   code = args.GetRawPart();
 362
 363   // The position where the expression starts in the command line.
 364   assert(original_code_size >= code.size());
 365   std::size_t raw_start = original_code_size - code.size();
 366
 367   // Check if the cursor is actually in the expression string, and if not, we
 368   // exit.
 369   // FIXME: We should complete the options here.
 370   if (cursor_pos < raw_start)
 371     return;
 372
 373   // Make the cursor_pos again relative to the start of the code string.
 374   assert(cursor_pos >= raw_start);
 375   cursor_pos -= raw_start;
 376
 377   auto language = exe_ctx.GetFrameRef().GetLanguage();
 378
 379   Status error;
 380   lldb::UserExpressionSP expr(target.GetUserExpressionForLanguage(
 381       code, llvm::StringRef(), language, UserExpression::eResultTypeAny,
 382       options, nullptr, error));
 383   if (error.Fail())
 384     return;
 385
 386   expr->Complete(exe_ctx, request, cursor_pos);
 387 }
 388
 389 static lldb_private::Status
 390 CanBeUsedForElementCountPrinting(ValueObject &valobj) {
 391   CompilerType type(valobj.GetCompilerType());
 392   CompilerType pointee;
 393   if (!type.IsPointerType(&pointee))
 394     return Status::FromErrorString("as it does not refer to a pointer");
 395   if (pointee.IsVoidType())
 396     return Status::FromErrorString("as it refers to a pointer to void");
 397   return Status();
 398 }
 399
 400 bool CommandObjectExpression::EvaluateExpression(llvm::StringRef expr,
 401                                                  Stream &output_stream,
 402                                                  Stream &error_stream,
 403                                                  CommandReturnObject &result) {
 404   // Don't use m_exe_ctx as this might be called asynchronously after the
 405   // command object DoExecute has finished when doing multi-line expression
 406   // that use an input reader...
 407   ExecutionContext exe_ctx(m_interpreter.GetExecutionContext());
 408   Target *exe_target = exe_ctx.GetTargetPtr();
 409   Target &target = exe_target ? *exe_target : GetDummyTarget();
 410
 411   lldb::ValueObjectSP result_valobj_sp;
 412   StackFrame *frame = exe_ctx.GetFramePtr();
 413
 414   if (m_command_options.top_level && !m_command_options.allow_jit) {
 415     result.AppendErrorWithFormat(
 416         "Can't disable JIT compilation for top-level expressions.\n");
 417     return false;
 418   }
 419
 420   EvaluateExpressionOptions eval_options =
 421       m_command_options.GetEvaluateExpressionOptions(target, m_varobj_options);
 422   // This command manually removes the result variable, make sure expression
 423   // evaluation doesn't do it first.
 424   eval_options.SetSuppressPersistentResult(false);
 425
 426   ExpressionResults success = target.EvaluateExpression(
 427       expr, frame, result_valobj_sp, eval_options, &m_fixed_expression);
 428
 429   // Only mention Fix-Its if the expression evaluator applied them.
 430   // Compiler errors refer to the final expression after applying Fix-It(s).
 431   if (!m_fixed_expression.empty() && target.GetEnableNotifyAboutFixIts()) {
 432     error_stream << "  Evaluated this expression after applying Fix-It(s):\n";
 433     error_stream << "    " << m_fixed_expression << "\n";
 434   }
 435
 436   if (result_valobj_sp) {
 437     Format format = m_format_options.GetFormat();
 438
 439     if (result_valobj_sp->GetError().Success()) {
 440       if (format != eFormatVoid) {
 441         if (format != eFormatDefault)
 442           result_valobj_sp->SetFormat(format);
 443
 444         if (m_varobj_options.elem_count > 0) {
 445           Status error(CanBeUsedForElementCountPrinting(*result_valobj_sp));
 446           if (error.Fail()) {
 447             result.AppendErrorWithFormat(
 448                 "expression cannot be used with --element-count %s\n",
 449                 error.AsCString(""));
 450             return false;
 451           }
 452         }
 453
 454         bool suppress_result =
 455             m_command_options.ShouldSuppressResult(m_varobj_options);
 456
 457         DumpValueObjectOptions options(m_varobj_options.GetAsDumpOptions(
 458             m_command_options.m_verbosity, format));
 459         options.SetHideRootName(suppress_result);
 460         options.SetVariableFormatDisplayLanguage(
 461             result_valobj_sp->GetPreferredDisplayLanguage());
 462
 463         if (llvm::Error error =
 464                 result_valobj_sp->Dump(output_stream, options)) {
 465           result.AppendError(toString(std::move(error)));
 466           return false;
 467         }
 468
 469         if (suppress_result)
 470           if (auto result_var_sp =
 471                   target.GetPersistentVariable(result_valobj_sp->GetName())) {
 472             auto language = result_valobj_sp->GetPreferredDisplayLanguage();
 473             if (auto *persistent_state =
 474                     target.GetPersistentExpressionStateForLanguage(language))
 475               persistent_state->RemovePersistentVariable(result_var_sp);
 476           }
 477         result.SetStatus(eReturnStatusSuccessFinishResult);
 478       }
 479     } else {
 480       if (result_valobj_sp->GetError().GetError() ==
 481           UserExpression::kNoResult) {
 482         if (format != eFormatVoid && GetDebugger().GetNotifyVoid()) {
 483           error_stream.PutCString("(void)\n");
 484         }
 485
 486         result.SetStatus(eReturnStatusSuccessFinishResult);
 487       } else {
 488         result.SetStatus(eReturnStatusFailed);
 489         result.SetError(result_valobj_sp->GetError().ToError());
 490       }
 491     }
 492   } else {
 493     error_stream.Printf("error: unknown error\n");
 494   }
 495
 496   return (success != eExpressionSetupError &&
 497           success != eExpressionParseError);
 498 }
 499
 500 void CommandObjectExpression::IOHandlerInputComplete(IOHandler &io_handler,
 501                                                      std::string &line) {
 502   io_handler.SetIsDone(true);
 503   StreamFileSP output_sp = io_handler.GetOutputStreamFileSP();
 504   StreamFileSP error_sp = io_handler.GetErrorStreamFileSP();
 505
 506   CommandReturnObject return_obj(
 507       GetCommandInterpreter().GetDebugger().GetUseColor());
 508   EvaluateExpression(line.c_str(), *output_sp, *error_sp, return_obj);
 509
 510   if (output_sp)
 511     output_sp->Flush();
 512   if (error_sp) {
 513     *error_sp << return_obj.GetErrorString();
 514     error_sp->Flush();
 515   }
 516 }
 517
 518 bool CommandObjectExpression::IOHandlerIsInputComplete(IOHandler &io_handler,
 519                                                        StringList &lines) {
 520   // An empty lines is used to indicate the end of input
 521   const size_t num_lines = lines.GetSize();
 522   if (num_lines > 0 && lines[num_lines - 1].empty()) {
 523     // Remove the last empty line from "lines" so it doesn't appear in our
 524     // resulting input and return true to indicate we are done getting lines
 525     lines.PopBack();
 526     return true;
 527   }
 528   return false;
 529 }
 530
 531 void CommandObjectExpression::GetMultilineExpression() {
 532   m_expr_lines.clear();
 533   m_expr_line_count = 0;
 534
 535   Debugger &debugger = GetCommandInterpreter().GetDebugger();
 536   bool color_prompt = debugger.GetUseColor();
 537   const bool multiple_lines = true; // Get multiple lines
 538   IOHandlerSP io_handler_sp(
 539       new IOHandlerEditline(debugger, IOHandler::Type::Expression,
 540                             "lldb-expr", // Name of input reader for history
 541                             llvm::StringRef(), // No prompt
 542                             llvm::StringRef(), // Continuation prompt
 543                             multiple_lines, color_prompt,
 544                             1, // Show line numbers starting at 1
 545                             *this));
 546
 547   StreamFileSP output_sp = io_handler_sp->GetOutputStreamFileSP();
 548   if (output_sp) {
 549     output_sp->PutCString(
 550         "Enter expressions, then terminate with an empty line to evaluate:\n");
 551     output_sp->Flush();
 552   }
 553   debugger.RunIOHandlerAsync(io_handler_sp);
 554 }
 555
 556 static EvaluateExpressionOptions
 557 GetExprOptions(ExecutionContext &ctx,
 558                CommandObjectExpression::CommandOptions command_options) {
 559   command_options.OptionParsingStarting(&ctx);
 560
 561   // Default certain settings for REPL regardless of the global settings.
 562   command_options.unwind_on_error = false;
 563   command_options.ignore_breakpoints = false;
 564   command_options.debug = false;
 565
 566   EvaluateExpressionOptions expr_options;
 567   expr_options.SetUnwindOnError(command_options.unwind_on_error);
 568   expr_options.SetIgnoreBreakpoints(command_options.ignore_breakpoints);
 569   expr_options.SetTryAllThreads(command_options.try_all_threads);
 570
 571   if (command_options.timeout > 0)
 572     expr_options.SetTimeout(std::chrono::microseconds(command_options.timeout));
 573   else
 574     expr_options.SetTimeout(std::nullopt);
 575
 576   return expr_options;
 577 }
 578
 579 void CommandObjectExpression::DoExecute(llvm::StringRef command,
 580                                         CommandReturnObject &result) {
 581   m_fixed_expression.clear();
 582   auto exe_ctx = GetCommandInterpreter().GetExecutionContext();
 583   m_option_group.NotifyOptionParsingStarting(&exe_ctx);
 584
 585   if (command.empty()) {
 586     GetMultilineExpression();
 587     return;
 588   }
 589
 590   OptionsWithRaw args(command);
 591   llvm::StringRef expr = args.GetRawPart();
 592
 593   if (args.HasArgs()) {
 594     if (!ParseOptionsAndNotify(args.GetArgs(), result, m_option_group, exe_ctx))
 595       return;
 596
 597     if (m_repl_option.GetOptionValue().GetCurrentValue()) {
 598       Target &target = GetTarget();
 599       // Drop into REPL
 600       m_expr_lines.clear();
 601       m_expr_line_count = 0;
 602
 603       Debugger &debugger = target.GetDebugger();
 604
 605       // Check if the LLDB command interpreter is sitting on top of a REPL
 606       // that launched it...
 607       if (debugger.CheckTopIOHandlerTypes(IOHandler::Type::CommandInterpreter,
 608                                           IOHandler::Type::REPL)) {
 609         // the LLDB command interpreter is sitting on top of a REPL that
 610         // launched it, so just say the command interpreter is done and
 611         // fall back to the existing REPL
 612         m_interpreter.GetIOHandler(false)->SetIsDone(true);
 613       } else {
 614         // We are launching the REPL on top of the current LLDB command
 615         // interpreter, so just push one
 616         bool initialize = false;
 617         Status repl_error;
 618         REPLSP repl_sp(target.GetREPL(repl_error, m_command_options.language,
 619                                        nullptr, false));
 620
 621         if (!repl_sp) {
 622           initialize = true;
 623           repl_sp = target.GetREPL(repl_error, m_command_options.language,
 624                                     nullptr, true);
 625           if (repl_error.Fail()) {
 626             result.SetError(std::move(repl_error));
 627             return;
 628           }
 629         }
 630
 631         if (repl_sp) {
 632           if (initialize) {
 633             repl_sp->SetEvaluateOptions(
 634                 GetExprOptions(exe_ctx, m_command_options));
 635             repl_sp->SetFormatOptions(m_format_options);
 636             repl_sp->SetValueObjectDisplayOptions(m_varobj_options);
 637           }
 638
 639           IOHandlerSP io_handler_sp(repl_sp->GetIOHandler());
 640           io_handler_sp->SetIsDone(false);
 641           debugger.RunIOHandlerAsync(io_handler_sp);
 642         } else {
 643           repl_error = Status::FromErrorStringWithFormat(
 644               "Couldn't create a REPL for %s",
 645               Language::GetNameForLanguageType(m_command_options.language));
 646           result.SetError(std::move(repl_error));
 647           return;
 648         }
 649       }
 650     }
 651     // No expression following options
 652     else if (expr.empty()) {
 653       GetMultilineExpression();
 654       return;
 655     }
 656   }
 657
 658   // Previously the indent was set up for diagnosing command line
 659   // parsing errors. Now point it to the expression.
 660   std::optional<uint16_t> indent;
 661   size_t pos = m_original_command.rfind(expr);
 662   if (pos != llvm::StringRef::npos)
 663     indent = pos;
 664   result.SetDiagnosticIndent(indent);
 665
 666   Target &target = GetTarget();
 667   if (EvaluateExpression(expr, result.GetOutputStream(),
 668                          result.GetErrorStream(), result)) {
 669
 670     if (!m_fixed_expression.empty() && target.GetEnableNotifyAboutFixIts()) {
 671       CommandHistory &history = m_interpreter.GetCommandHistory();
 672       // FIXME: Can we figure out what the user actually typed (e.g. some alias
 673       // for expr???)
 674       // If we can it would be nice to show that.
 675       std::string fixed_command("expression ");
 676       if (args.HasArgs()) {
 677         // Add in any options that might have been in the original command:
 678         fixed_command.append(std::string(args.GetArgStringWithDelimiter()));
 679         fixed_command.append(m_fixed_expression);
 680       } else
 681         fixed_command.append(m_fixed_expression);
 682       history.AppendString(fixed_command);
 683     }
 684     return;
 685   }
 686   result.SetStatus(eReturnStatusFailed);
 687 }