xref: /llvm-project/lldb/source/Commands/CommandObjectExpression.cpp (revision ecbb0bb1690cd59da0224d7b906f968356b1265c)
1 //===-- CommandObjectExpression.cpp -----------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 // C Includes
11 // C++ Includes
12 // Other libraries and framework includes
13 #include "llvm/ADT/STLExtras.h"
14 #include "llvm/ADT/StringRef.h"
15 
16 // Project includes
17 #include "CommandObjectExpression.h"
18 #include "Plugins/ExpressionParser/Clang/ClangExpressionVariable.h"
19 #include "lldb/Core/Debugger.h"
20 #include "lldb/Core/Value.h"
21 #include "lldb/Core/ValueObjectVariable.h"
22 #include "lldb/DataFormatters/ValueObjectPrinter.h"
23 #include "lldb/Expression/DWARFExpression.h"
24 #include "lldb/Expression/REPL.h"
25 #include "lldb/Expression/UserExpression.h"
26 #include "lldb/Host/Host.h"
27 #include "lldb/Host/StringConvert.h"
28 #include "lldb/Interpreter/CommandInterpreter.h"
29 #include "lldb/Interpreter/CommandReturnObject.h"
30 #include "lldb/Symbol/ObjectFile.h"
31 #include "lldb/Symbol/Variable.h"
32 #include "lldb/Target/Language.h"
33 #include "lldb/Target/Process.h"
34 #include "lldb/Target/StackFrame.h"
35 #include "lldb/Target/Target.h"
36 #include "lldb/Target/Thread.h"
37 
38 using namespace lldb;
39 using namespace lldb_private;
40 
41 CommandObjectExpression::CommandOptions::CommandOptions() : OptionGroup() {}
42 
43 CommandObjectExpression::CommandOptions::~CommandOptions() = default;
44 
45 static OptionEnumValueElement g_description_verbosity_type[] = {
46     {eLanguageRuntimeDescriptionDisplayVerbosityCompact, "compact",
47      "Only show the description string"},
48     {eLanguageRuntimeDescriptionDisplayVerbosityFull, "full",
49      "Show the full output, including persistent variable's name and type"},
50     {0, nullptr, nullptr}};
51 
52 OptionDefinition CommandObjectExpression::CommandOptions::g_option_table[] = {
53     // clang-format off
54   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "all-threads",           'a', OptionParser::eRequiredArgument, nullptr, nullptr,                      0, eArgTypeBoolean,              "Should we run all threads if the execution doesn't complete on one thread."},
55   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "ignore-breakpoints",    'i', OptionParser::eRequiredArgument, nullptr, nullptr,                      0, eArgTypeBoolean,              "Ignore breakpoint hits while running expressions"},
56   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "timeout",               't', OptionParser::eRequiredArgument, nullptr, nullptr,                      0, eArgTypeUnsignedInteger,      "Timeout value (in microseconds) for running the expression."},
57   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "unwind-on-error",       'u', OptionParser::eRequiredArgument, nullptr, nullptr,                      0, eArgTypeBoolean,              "Clean up program state if the expression causes a crash, or raises a signal.  "
58                                                                                                                                                                                   "Note, unlike gdb hitting a breakpoint is controlled by another option (-i)."},
59   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "debug",                 'g', OptionParser::eNoArgument,       nullptr, nullptr,                      0, eArgTypeNone,                 "When specified, debug the JIT code by setting a breakpoint on the first instruction "
60                                                                                                                                                                                   "and forcing breakpoints to not be ignored (-i0) and no unwinding to happen on error (-u0)."},
61   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "language",              'l', OptionParser::eRequiredArgument, nullptr, nullptr,                      0, eArgTypeLanguage,             "Specifies the Language to use when parsing the expression.  If not set the target.language "
62                                                                                                                                                                                   "setting is used." },
63   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "apply-fixits",          'X', OptionParser::eRequiredArgument, nullptr, nullptr,                      0, eArgTypeLanguage,             "If true, simple fix-it hints will be automatically applied to the expression." },
64   {LLDB_OPT_SET_1,                  false, "description-verbosity", 'v', OptionParser::eOptionalArgument, nullptr, g_description_verbosity_type, 0, eArgTypeDescriptionVerbosity, "How verbose should the output of this expression be, if the object description is asked for."},
65   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "top-level",             'p', OptionParser::eNoArgument,       nullptr, nullptr,                      0, eArgTypeNone,                 "Interpret the expression as top-level definitions rather than code to be immediately "
66                                                                                                                                                                                   "executed."},
67   {LLDB_OPT_SET_1 | LLDB_OPT_SET_2, false, "allow-jit",             'j', OptionParser::eRequiredArgument, nullptr, nullptr,                      0, eArgTypeBoolean,              "Controls whether the expression can fall back to being JITted if it's not supported by "
68                                                                                                                                                                                   "the interpreter (defaults to true)."}
69     // clang-format on
70 };
71 
72 uint32_t CommandObjectExpression::CommandOptions::GetNumDefinitions() {
73   return llvm::array_lengthof(g_option_table);
74 }
75 
76 Error CommandObjectExpression::CommandOptions::SetOptionValue(
77     uint32_t option_idx, const char *option_arg,
78     ExecutionContext *execution_context) {
79   Error error;
80 
81   auto option_strref = llvm::StringRef::withNullAsEmpty(option_arg);
82   const int short_option = g_option_table[option_idx].short_option;
83 
84   switch (short_option) {
85   case 'l':
86     language = Language::GetLanguageTypeFromString(option_arg);
87     if (language == eLanguageTypeUnknown)
88       error.SetErrorStringWithFormat(
89           "unknown language type: '%s' for expression", option_arg);
90     break;
91 
92   case 'a': {
93     bool success;
94     bool result;
95     result = Args::StringToBoolean(option_strref, true, &success);
96     if (!success)
97       error.SetErrorStringWithFormat(
98           "invalid all-threads value setting: \"%s\"", option_arg);
99     else
100       try_all_threads = result;
101   } break;
102 
103   case 'i': {
104     bool success;
105     bool tmp_value = Args::StringToBoolean(option_strref, true, &success);
106     if (success)
107       ignore_breakpoints = tmp_value;
108     else
109       error.SetErrorStringWithFormat(
110           "could not convert \"%s\" to a boolean value.", option_arg);
111     break;
112   }
113 
114   case 'j': {
115     bool success;
116     bool tmp_value = Args::StringToBoolean(option_strref, true, &success);
117     if (success)
118       allow_jit = tmp_value;
119     else
120       error.SetErrorStringWithFormat(
121           "could not convert \"%s\" to a boolean value.", option_arg);
122     break;
123   }
124 
125   case 't': {
126     bool success;
127     uint32_t result;
128     result = StringConvert::ToUInt32(option_arg, 0, 0, &success);
129     if (success)
130       timeout = result;
131     else
132       error.SetErrorStringWithFormat("invalid timeout setting \"%s\"",
133                                      option_arg);
134   } break;
135 
136   case 'u': {
137     bool success;
138     bool tmp_value = Args::StringToBoolean(option_strref, true, &success);
139     if (success)
140       unwind_on_error = tmp_value;
141     else
142       error.SetErrorStringWithFormat(
143           "could not convert \"%s\" to a boolean value.", option_arg);
144     break;
145   }
146 
147   case 'v':
148     if (!option_arg) {
149       m_verbosity = eLanguageRuntimeDescriptionDisplayVerbosityFull;
150       break;
151     }
152     m_verbosity =
153         (LanguageRuntimeDescriptionDisplayVerbosity)Args::StringToOptionEnum(
154             option_arg, g_option_table[option_idx].enum_values, 0, error);
155     if (!error.Success())
156       error.SetErrorStringWithFormat(
157           "unrecognized value for description-verbosity '%s'", option_arg);
158     break;
159 
160   case 'g':
161     debug = true;
162     unwind_on_error = false;
163     ignore_breakpoints = false;
164     break;
165 
166   case 'p':
167     top_level = true;
168     break;
169 
170   case 'X': {
171     bool success;
172     bool tmp_value = Args::StringToBoolean(option_strref, true, &success);
173     if (success)
174       auto_apply_fixits = tmp_value ? eLazyBoolYes : eLazyBoolNo;
175     else
176       error.SetErrorStringWithFormat(
177           "could not convert \"%s\" to a boolean value.", option_arg);
178     break;
179   }
180 
181   default:
182     error.SetErrorStringWithFormat("invalid short option character '%c'",
183                                    short_option);
184     break;
185   }
186 
187   return error;
188 }
189 
190 void CommandObjectExpression::CommandOptions::OptionParsingStarting(
191     ExecutionContext *execution_context) {
192   auto process_sp =
193       execution_context ? execution_context->GetProcessSP() : ProcessSP();
194   if (process_sp) {
195     ignore_breakpoints = process_sp->GetIgnoreBreakpointsInExpressions();
196     unwind_on_error = process_sp->GetUnwindOnErrorInExpressions();
197   } else {
198     ignore_breakpoints = true;
199     unwind_on_error = true;
200   }
201 
202   show_summary = true;
203   try_all_threads = true;
204   timeout = 0;
205   debug = false;
206   language = eLanguageTypeUnknown;
207   m_verbosity = eLanguageRuntimeDescriptionDisplayVerbosityCompact;
208   auto_apply_fixits = eLazyBoolCalculate;
209   top_level = false;
210   allow_jit = true;
211 }
212 
213 const OptionDefinition *
214 CommandObjectExpression::CommandOptions::GetDefinitions() {
215   return g_option_table;
216 }
217 
218 CommandObjectExpression::CommandObjectExpression(
219     CommandInterpreter &interpreter)
220     : CommandObjectRaw(
221           interpreter, "expression", "Evaluate an expression on the current "
222                                      "thread.  Displays any returned value "
223                                      "with LLDB's default formatting.",
224           nullptr, eCommandProcessMustBePaused | eCommandTryTargetAPILock),
225       IOHandlerDelegate(IOHandlerDelegate::Completion::Expression),
226       m_option_group(), m_format_options(eFormatDefault),
227       m_repl_option(LLDB_OPT_SET_1, false, "repl", 'r', "Drop into REPL", false,
228                     true),
229       m_command_options(), m_expr_line_count(0), m_expr_lines() {
230   SetHelpLong(
231       R"(
232 Timeouts:
233 
234 )"
235       "    If the expression can be evaluated statically (without running code) then it will be.  \
236 Otherwise, by default the expression will run on the current thread with a short timeout: \
237 currently .25 seconds.  If it doesn't return in that time, the evaluation will be interrupted \
238 and resumed with all threads running.  You can use the -a option to disable retrying on all \
239 threads.  You can use the -t option to set a shorter timeout."
240       R"(
241 
242 User defined variables:
243 
244 )"
245       "    You can define your own variables for convenience or to be used in subsequent expressions.  \
246 You define them the same way you would define variables in C.  If the first character of \
247 your user defined variable is a $, then the variable's value will be available in future \
248 expressions, otherwise it will just be available in the current expression."
249       R"(
250 
251 Continuing evaluation after a breakpoint:
252 
253 )"
254       "    If the \"-i false\" option is used, and execution is interrupted by a breakpoint hit, once \
255 you are done with your investigation, you can either remove the expression execution frames \
256 from the stack with \"thread return -x\" or if you are still interested in the expression result \
257 you can issue the \"continue\" command and the expression evaluation will complete and the \
258 expression result will be available using the \"thread.completed-expression\" key in the thread \
259 format."
260       R"(
261 
262 Examples:
263 
264     expr my_struct->a = my_array[3]
265     expr -f bin -- (index * 8) + 5
266     expr unsigned int $foo = 5
267     expr char c[] = \"foo\"; c[0])");
268 
269   CommandArgumentEntry arg;
270   CommandArgumentData expression_arg;
271 
272   // Define the first (and only) variant of this arg.
273   expression_arg.arg_type = eArgTypeExpression;
274   expression_arg.arg_repetition = eArgRepeatPlain;
275 
276   // There is only one variant this argument could be; put it into the argument
277   // entry.
278   arg.push_back(expression_arg);
279 
280   // Push the data for the first argument into the m_arguments vector.
281   m_arguments.push_back(arg);
282 
283   // Add the "--format" and "--gdb-format"
284   m_option_group.Append(&m_format_options,
285                         OptionGroupFormat::OPTION_GROUP_FORMAT |
286                             OptionGroupFormat::OPTION_GROUP_GDB_FMT,
287                         LLDB_OPT_SET_1);
288   m_option_group.Append(&m_command_options);
289   m_option_group.Append(&m_varobj_options, LLDB_OPT_SET_ALL,
290                         LLDB_OPT_SET_1 | LLDB_OPT_SET_2);
291   m_option_group.Append(&m_repl_option, LLDB_OPT_SET_ALL, LLDB_OPT_SET_3);
292   m_option_group.Finalize();
293 }
294 
295 CommandObjectExpression::~CommandObjectExpression() = default;
296 
297 Options *CommandObjectExpression::GetOptions() { return &m_option_group; }
298 
299 static lldb_private::Error
300 CanBeUsedForElementCountPrinting(ValueObject &valobj) {
301   CompilerType type(valobj.GetCompilerType());
302   CompilerType pointee;
303   if (!type.IsPointerType(&pointee))
304     return Error("as it does not refer to a pointer");
305   if (pointee.IsVoidType())
306     return Error("as it refers to a pointer to void");
307   return Error();
308 }
309 
310 bool CommandObjectExpression::EvaluateExpression(const char *expr,
311                                                  Stream *output_stream,
312                                                  Stream *error_stream,
313                                                  CommandReturnObject *result) {
314   // Don't use m_exe_ctx as this might be called asynchronously
315   // after the command object DoExecute has finished when doing
316   // multi-line expression that use an input reader...
317   ExecutionContext exe_ctx(m_interpreter.GetExecutionContext());
318 
319   Target *target = exe_ctx.GetTargetPtr();
320 
321   if (!target)
322     target = GetDummyTarget();
323 
324   if (target) {
325     lldb::ValueObjectSP result_valobj_sp;
326     bool keep_in_memory = true;
327     StackFrame *frame = exe_ctx.GetFramePtr();
328 
329     EvaluateExpressionOptions options;
330     options.SetCoerceToId(m_varobj_options.use_objc);
331     options.SetUnwindOnError(m_command_options.unwind_on_error);
332     options.SetIgnoreBreakpoints(m_command_options.ignore_breakpoints);
333     options.SetKeepInMemory(keep_in_memory);
334     options.SetUseDynamic(m_varobj_options.use_dynamic);
335     options.SetTryAllThreads(m_command_options.try_all_threads);
336     options.SetDebug(m_command_options.debug);
337     options.SetLanguage(m_command_options.language);
338     options.SetExecutionPolicy(
339         m_command_options.allow_jit
340             ? EvaluateExpressionOptions::default_execution_policy
341             : lldb_private::eExecutionPolicyNever);
342 
343     bool auto_apply_fixits;
344     if (m_command_options.auto_apply_fixits == eLazyBoolCalculate)
345       auto_apply_fixits = target->GetEnableAutoApplyFixIts();
346     else
347       auto_apply_fixits =
348           m_command_options.auto_apply_fixits == eLazyBoolYes ? true : false;
349 
350     options.SetAutoApplyFixIts(auto_apply_fixits);
351 
352     if (m_command_options.top_level)
353       options.SetExecutionPolicy(eExecutionPolicyTopLevel);
354 
355     // If there is any chance we are going to stop and want to see
356     // what went wrong with our expression, we should generate debug info
357     if (!m_command_options.ignore_breakpoints ||
358         !m_command_options.unwind_on_error)
359       options.SetGenerateDebugInfo(true);
360 
361     if (m_command_options.timeout > 0)
362       options.SetTimeoutUsec(m_command_options.timeout);
363     else
364       options.SetTimeoutUsec(0);
365 
366     ExpressionResults success = target->EvaluateExpression(
367         expr, frame, result_valobj_sp, options, &m_fixed_expression);
368 
369     // We only tell you about the FixIt if we applied it.  The compiler errors
370     // will suggest the FixIt if it parsed.
371     if (error_stream && !m_fixed_expression.empty() &&
372         target->GetEnableNotifyAboutFixIts()) {
373       if (success == eExpressionCompleted)
374         error_stream->Printf(
375             "  Fix-it applied, fixed expression was: \n    %s\n",
376             m_fixed_expression.c_str());
377     }
378 
379     if (result_valobj_sp) {
380       Format format = m_format_options.GetFormat();
381 
382       if (result_valobj_sp->GetError().Success()) {
383         if (format != eFormatVoid) {
384           if (format != eFormatDefault)
385             result_valobj_sp->SetFormat(format);
386 
387           if (m_varobj_options.elem_count > 0) {
388             Error error(CanBeUsedForElementCountPrinting(*result_valobj_sp));
389             if (error.Fail()) {
390               result->AppendErrorWithFormat(
391                   "expression cannot be used with --element-count %s\n",
392                   error.AsCString(""));
393               result->SetStatus(eReturnStatusFailed);
394               return false;
395             }
396           }
397 
398           DumpValueObjectOptions options(m_varobj_options.GetAsDumpOptions(
399               m_command_options.m_verbosity, format));
400           options.SetVariableFormatDisplayLanguage(
401               result_valobj_sp->GetPreferredDisplayLanguage());
402 
403           result_valobj_sp->Dump(*output_stream, options);
404 
405           if (result)
406             result->SetStatus(eReturnStatusSuccessFinishResult);
407         }
408       } else {
409         if (result_valobj_sp->GetError().GetError() ==
410             UserExpression::kNoResult) {
411           if (format != eFormatVoid &&
412               m_interpreter.GetDebugger().GetNotifyVoid()) {
413             error_stream->PutCString("(void)\n");
414           }
415 
416           if (result)
417             result->SetStatus(eReturnStatusSuccessFinishResult);
418         } else {
419           const char *error_cstr = result_valobj_sp->GetError().AsCString();
420           if (error_cstr && error_cstr[0]) {
421             const size_t error_cstr_len = strlen(error_cstr);
422             const bool ends_with_newline =
423                 error_cstr[error_cstr_len - 1] == '\n';
424             if (strstr(error_cstr, "error:") != error_cstr)
425               error_stream->PutCString("error: ");
426             error_stream->Write(error_cstr, error_cstr_len);
427             if (!ends_with_newline)
428               error_stream->EOL();
429           } else {
430             error_stream->PutCString("error: unknown error\n");
431           }
432 
433           if (result)
434             result->SetStatus(eReturnStatusFailed);
435         }
436       }
437     }
438   } else {
439     error_stream->Printf("error: invalid execution context for expression\n");
440     return false;
441   }
442 
443   return true;
444 }
445 
446 void CommandObjectExpression::IOHandlerInputComplete(IOHandler &io_handler,
447                                                      std::string &line) {
448   io_handler.SetIsDone(true);
449   //    StreamSP output_stream =
450   //    io_handler.GetDebugger().GetAsyncOutputStream();
451   //    StreamSP error_stream = io_handler.GetDebugger().GetAsyncErrorStream();
452   StreamFileSP output_sp(io_handler.GetOutputStreamFile());
453   StreamFileSP error_sp(io_handler.GetErrorStreamFile());
454 
455   EvaluateExpression(line.c_str(), output_sp.get(), error_sp.get());
456   if (output_sp)
457     output_sp->Flush();
458   if (error_sp)
459     error_sp->Flush();
460 }
461 
462 bool CommandObjectExpression::IOHandlerIsInputComplete(IOHandler &io_handler,
463                                                        StringList &lines) {
464   // An empty lines is used to indicate the end of input
465   const size_t num_lines = lines.GetSize();
466   if (num_lines > 0 && lines[num_lines - 1].empty()) {
467     // Remove the last empty line from "lines" so it doesn't appear
468     // in our resulting input and return true to indicate we are done
469     // getting lines
470     lines.PopBack();
471     return true;
472   }
473   return false;
474 }
475 
476 void CommandObjectExpression::GetMultilineExpression() {
477   m_expr_lines.clear();
478   m_expr_line_count = 0;
479 
480   Debugger &debugger = GetCommandInterpreter().GetDebugger();
481   bool color_prompt = debugger.GetUseColor();
482   const bool multiple_lines = true; // Get multiple lines
483   IOHandlerSP io_handler_sp(
484       new IOHandlerEditline(debugger, IOHandler::Type::Expression,
485                             "lldb-expr", // Name of input reader for history
486                             nullptr,     // No prompt
487                             nullptr,     // Continuation prompt
488                             multiple_lines, color_prompt,
489                             1, // Show line numbers starting at 1
490                             *this));
491 
492   StreamFileSP output_sp(io_handler_sp->GetOutputStreamFile());
493   if (output_sp) {
494     output_sp->PutCString(
495         "Enter expressions, then terminate with an empty line to evaluate:\n");
496     output_sp->Flush();
497   }
498   debugger.PushIOHandler(io_handler_sp);
499 }
500 
501 bool CommandObjectExpression::DoExecute(const char *command,
502                                         CommandReturnObject &result) {
503   m_fixed_expression.clear();
504   auto exe_ctx = GetCommandInterpreter().GetExecutionContext();
505   m_option_group.NotifyOptionParsingStarting(&exe_ctx);
506 
507   const char *expr = nullptr;
508 
509   if (command[0] == '\0') {
510     GetMultilineExpression();
511     return result.Succeeded();
512   }
513 
514   if (command[0] == '-') {
515     // We have some options and these options MUST end with --.
516     const char *end_options = nullptr;
517     const char *s = command;
518     while (s && s[0]) {
519       end_options = ::strstr(s, "--");
520       if (end_options) {
521         end_options += 2; // Get past the "--"
522         if (::isspace(end_options[0])) {
523           expr = end_options;
524           while (::isspace(*expr))
525             ++expr;
526           break;
527         }
528       }
529       s = end_options;
530     }
531 
532     if (end_options) {
533       Args args(llvm::StringRef(command, end_options - command));
534       if (!ParseOptions(args, result))
535         return false;
536 
537       Error error(m_option_group.NotifyOptionParsingFinished(&exe_ctx));
538       if (error.Fail()) {
539         result.AppendError(error.AsCString());
540         result.SetStatus(eReturnStatusFailed);
541         return false;
542       }
543 
544       if (m_repl_option.GetOptionValue().GetCurrentValue()) {
545         Target *target = m_interpreter.GetExecutionContext().GetTargetPtr();
546         if (target) {
547           // Drop into REPL
548           m_expr_lines.clear();
549           m_expr_line_count = 0;
550 
551           Debugger &debugger = target->GetDebugger();
552 
553           // Check if the LLDB command interpreter is sitting on top of a REPL
554           // that
555           // launched it...
556           if (debugger.CheckTopIOHandlerTypes(
557                   IOHandler::Type::CommandInterpreter, IOHandler::Type::REPL)) {
558             // the LLDB command interpreter is sitting on top of a REPL that
559             // launched it,
560             // so just say the command interpreter is done and fall back to the
561             // existing REPL
562             m_interpreter.GetIOHandler(false)->SetIsDone(true);
563           } else {
564             // We are launching the REPL on top of the current LLDB command
565             // interpreter,
566             // so just push one
567             bool initialize = false;
568             Error repl_error;
569             REPLSP repl_sp(target->GetREPL(
570                 repl_error, m_command_options.language, nullptr, false));
571 
572             if (!repl_sp) {
573               initialize = true;
574               repl_sp = target->GetREPL(repl_error, m_command_options.language,
575                                         nullptr, true);
576               if (!repl_error.Success()) {
577                 result.SetError(repl_error);
578                 return result.Succeeded();
579               }
580             }
581 
582             if (repl_sp) {
583               if (initialize) {
584                 repl_sp->SetCommandOptions(m_command_options);
585                 repl_sp->SetFormatOptions(m_format_options);
586                 repl_sp->SetValueObjectDisplayOptions(m_varobj_options);
587               }
588 
589               IOHandlerSP io_handler_sp(repl_sp->GetIOHandler());
590 
591               io_handler_sp->SetIsDone(false);
592 
593               debugger.PushIOHandler(io_handler_sp);
594             } else {
595               repl_error.SetErrorStringWithFormat(
596                   "Couldn't create a REPL for %s",
597                   Language::GetNameForLanguageType(m_command_options.language));
598               result.SetError(repl_error);
599               return result.Succeeded();
600             }
601           }
602         }
603       }
604       // No expression following options
605       else if (expr == nullptr || expr[0] == '\0') {
606         GetMultilineExpression();
607         return result.Succeeded();
608       }
609     }
610   }
611 
612   if (expr == nullptr)
613     expr = command;
614 
615   if (EvaluateExpression(expr, &(result.GetOutputStream()),
616                          &(result.GetErrorStream()), &result)) {
617     Target *target = m_interpreter.GetExecutionContext().GetTargetPtr();
618     if (!m_fixed_expression.empty() && target->GetEnableNotifyAboutFixIts()) {
619       CommandHistory &history = m_interpreter.GetCommandHistory();
620       // FIXME: Can we figure out what the user actually typed (e.g. some alias
621       // for expr???)
622       // If we can it would be nice to show that.
623       std::string fixed_command("expression ");
624       if (expr == command)
625         fixed_command.append(m_fixed_expression);
626       else {
627         // Add in any options that might have been in the original command:
628         fixed_command.append(command, expr - command);
629         fixed_command.append(m_fixed_expression);
630       }
631       history.AppendString(fixed_command);
632     }
633     return true;
634   }
635 
636   result.SetStatus(eReturnStatusFailed);
637   return false;
638 }
639