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