clayborg updated this revision to Diff 458310.
clayborg added a comment.

Use -grecord-command-line instead of setting RC_DEBUG_OPTIONS.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D133164/new/

https://reviews.llvm.org/D133164

Files:
  lldb/bindings/interface/SBValueList.i
  lldb/include/lldb/API/SBError.h
  lldb/include/lldb/API/SBValueList.h
  lldb/include/lldb/Symbol/SymbolFile.h
  lldb/include/lldb/Target/StackFrame.h
  lldb/packages/Python/lldbsuite/test/builders/builder.py
  lldb/packages/Python/lldbsuite/test/lldbtest.py
  lldb/source/API/SBFrame.cpp
  lldb/source/API/SBValueList.cpp
  lldb/source/Commands/CommandObjectFrame.cpp
  lldb/source/Core/IOHandlerCursesGUI.cpp
  lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
  lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
  lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
  lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
  lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
  lldb/source/Symbol/Variable.cpp
  lldb/source/Target/StackFrame.cpp
  lldb/test/API/commands/frame/var/TestFrameVar.py
  lldb/test/API/functionalities/archives/Makefile
  lldb/test/API/functionalities/archives/TestBSDArchives.py

Index: lldb/test/API/functionalities/archives/TestBSDArchives.py
===================================================================
--- lldb/test/API/functionalities/archives/TestBSDArchives.py
+++ lldb/test/API/functionalities/archives/TestBSDArchives.py
@@ -6,10 +6,16 @@
 from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
 from lldbsuite.test import lldbutil
-
+import os
+import time
 
 class BSDArchivesTestCase(TestBase):
 
+    # If your test case doesn't stress debug info, then
+    # set this to true.  That way it won't be run once for
+    # each debug info format.
+    NO_DEBUG_INFO_TESTCASE = True
+
     def setUp(self):
         # Call super's setUp().
         TestBase.setUp(self)
@@ -17,8 +23,6 @@
         self.line = line_number(
             'a.c', '// Set file and line breakpoint inside a().')
 
-    # Doesn't depend on any specific debug information.
-    @no_debug_info_test
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24527.  Makefile.rules doesn't know how to build static libs on Windows")
@@ -65,3 +69,80 @@
         num_specs = module_specs.GetSize()
         self.assertEqual(num_specs, 1)
         self.assertEqual(module_specs.GetSpecAtIndex(0).GetObjectName(), "c.o")
+
+
+    def check_frame_variable_errors(self, thread, error_strings):
+        command_result = lldb.SBCommandReturnObject()
+        interp = self.dbg.GetCommandInterpreter()
+        result = interp.HandleCommand("frame variable", command_result)
+        self.assertEqual(result, lldb.eReturnStatusFailed,
+                         "frame var succeeded unexpectedly")
+        command_error = command_result.GetError()
+
+        frame = thread.GetFrameAtIndex(0)
+        var_list = frame.GetVariables(True, True, False, True)
+        self.assertEqual(var_list.GetSize(), 0)
+        api_error = var_list.GetError().GetCString()
+
+        for s in error_strings:
+            self.assertTrue(s in command_error, 'Make sure "%s" exists in the command error "%s"' % (s, command_error))
+        for s in error_strings:
+            self.assertTrue(s in api_error, 'Make sure "%s" exists in the API error "%s"' % (s, api_error))
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    def test_frame_var_errors_when_archive_missing(self):
+        """
+            Break inside a() and remove libfoo.a to make sure we can't load
+            the debug information and report an appropriate error when doing
+            'frame variable'.
+        """
+        self.build()
+        exe = self.getBuildArtifact("a.out")
+        libfoo_path = self.getBuildArtifact("libfoo.a")
+        # Delete the main.o file that contains the debug info so we force an
+        # error when we run to main and try to get variables for the a()
+        # function. Since the libfoo.a is missing, the debug info won't be
+        # loaded and we should see an error when trying to read varibles.
+        os.unlink(libfoo_path)
+
+        (target, process, thread, bkpt) = lldbutil.run_to_name_breakpoint(
+                self, 'a', bkpt_module=exe)
+
+        error_strings = [
+            'debug map object file "',
+            'libfoo.a(a.o)" containing debug info does not exist, debug info will not be loaded'
+        ]
+        self.check_frame_variable_errors(thread, error_strings)
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    def test_frame_var_errors_when_mtime_mistmatch_for_object_in_archive(self):
+        """
+            Break inside a() and modify the modification time for "a.o" within
+            libfoo.a to make sure we can't load the debug information and
+            report an appropriate error when doing 'frame variable'.
+        """
+        self.build()
+        exe = self.getBuildArtifact("a.out")
+        a_path = self.getBuildArtifact("a.o")
+
+        # Change the modification time of the a.o object file after sleeping for
+        # 2 seconds to ensure the modification time is different. The rebuild
+        # only the "libfoo.a" target. This means the modification time of the
+        # a.o within libfoo.a will not match the debug map's modification time
+        # in a.out and will cause the debug information to not be loaded and we
+        # should get an appropriate error when reading variables.
+        time.sleep(2)
+        os.utime(a_path, None)
+        self.build(make_targets=["libfoo.a"])
+
+        (target, process, thread, bkpt) = lldbutil.run_to_name_breakpoint(
+                self, 'a', bkpt_module=exe)
+
+        error_strings = [
+            '"a.o" object from the "',
+            'libfoo.a" archive: either the .o file doesn\'t exist in the archive or the modification time (0x',
+            ') of the .o file doesn\'t match'
+        ]
+        self.check_frame_variable_errors(thread, error_strings)
Index: lldb/test/API/functionalities/archives/Makefile
===================================================================
--- lldb/test/API/functionalities/archives/Makefile
+++ lldb/test/API/functionalities/archives/Makefile
@@ -9,7 +9,7 @@
 
 libfoo.a: a.o b.o
 	$(AR) $(ARFLAGS) $@ $^
-	$(RM) $^
+	# $(RM) $^
 
 # This tests whether lldb can load a thin archive
 libbar.a: c.o
Index: lldb/test/API/commands/frame/var/TestFrameVar.py
===================================================================
--- lldb/test/API/commands/frame/var/TestFrameVar.py
+++ lldb/test/API/commands/frame/var/TestFrameVar.py
@@ -6,8 +6,10 @@
 
 import lldb
 import lldbsuite.test.lldbutil as lldbutil
+from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
-
+import os
+import time
 
 class TestFrameVar(TestBase):
 
@@ -82,4 +84,101 @@
         self.assertIn("g_var", output, "Globals didn't find g_var")
 
 
-
+    def check_frame_variable_errors(self, thread, error_strings):
+        command_result = lldb.SBCommandReturnObject()
+        interp = self.dbg.GetCommandInterpreter()
+        result = interp.HandleCommand("frame variable", command_result)
+        self.assertEqual(result, lldb.eReturnStatusFailed,
+                         "frame var succeeded unexpectedly")
+        command_error = command_result.GetError()
+
+        frame = thread.GetFrameAtIndex(0)
+        var_list = frame.GetVariables(True, True, False, True)
+        self.assertEqual(var_list.GetSize(), 0)
+        api_error = var_list.GetError().GetCString()
+
+        for s in error_strings:
+            self.assertTrue(s in command_error, 'Make sure "%s" exists in the command error "%s"' % (s, command_error))
+        for s in error_strings:
+            self.assertTrue(s in api_error, 'Make sure "%s" exists in the API error "%s"' % (s, api_error))
+
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    def test_darwin_dwarf_missing_obj(self):
+        '''
+            Test that if we build a binary with DWARF in .o files and we remove
+            the .o file for main.cpp, that we get an appropriate error when we
+            do 'frame variable' that explains why we aren't seeing variables.
+        '''
+        self.build(debug_info="dwarf")
+        exe = self.getBuildArtifact("a.out")
+        main_obj = self.getBuildArtifact("main.o")
+        # Delete the main.o file that contains the debug info so we force an
+        # error when we run to main and try to get variables
+        os.unlink(main_obj)
+
+        # We have to set a named breakpoint because we don't have any debug info
+        # because we deleted the main.o file.
+        (target, process, thread, bkpt) = lldbutil.run_to_name_breakpoint(self, 'main')
+        error_strings = [
+            'debug map object file "',
+            'main.o" containing debug info does not exist, debug info will not be loaded'
+        ]
+        self.check_frame_variable_errors(thread, error_strings)
+
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    def test_darwin_dwarf_obj_mod_time_mismatch(self):
+        '''
+            Test that if we build a binary with DWARF in .o files and we update
+            the mod time of the .o file for main.cpp, that we get an appropriate
+            error when we do 'frame variable' that explains why we aren't seeing
+            variables.
+        '''
+        self.build(debug_info="dwarf")
+        exe = self.getBuildArtifact("a.out")
+        main_obj = self.getBuildArtifact("main.o")
+
+        # Set the modification time for main.o file to the current time after
+        # sleeping for 2 seconds. This ensures the modification time will have
+        # changed and will not match the modification time in the debug map and
+        # force an error when we run to main and try to get variables
+        time.sleep(2)
+        os.utime(main_obj, None)
+
+        # We have to set a named breakpoint because we don't have any debug info
+        # because we deleted the main.o file since the mod times don't match
+        # and debug info won't be loaded
+        (target, process, thread, bkpt) = lldbutil.run_to_name_breakpoint(self, 'main')
+
+        error_strings = [
+            'debug map object file "',
+            'main.o" changed (actual: 0x',
+            ', debug map: 0x',
+            ') since this executable was linked, debug info will not be loaded'
+        ]
+        self.check_frame_variable_errors(thread, error_strings)
+
+
+    @skipIfRemote
+    @skipUnlessDarwin
+    def test_gline_tables_only(self):
+        '''
+            Test that if we build a binary with "-gline-tables-only" that we can
+            set a file and line breakpoint successfully, and get an error
+            letting us know that this build option was enabled when trying to
+            read variables.
+        '''
+        self.build(dictionary={'CFLAGS_EXTRAS': '-gline-tables-only -grecord-command-line'})
+        exe = self.getBuildArtifact("a.out")
+
+        # We have to set a named breakpoint because we don't have any debug info
+        # because we deleted the main.o file since the mod times don't match
+        # and debug info won't be loaded
+        (target, process, thread, bkpt) = lldbutil.run_to_name_breakpoint(self, 'main')
+        error_strings = [
+            '-gline-tables-only enabled, no variable information is available in debug info for this compile unit'
+        ]
+        self.check_frame_variable_errors(thread, error_strings)
Index: lldb/source/Target/StackFrame.cpp
===================================================================
--- lldb/source/Target/StackFrame.cpp
+++ lldb/source/Target/StackFrame.cpp
@@ -20,6 +20,7 @@
 #include "lldb/Symbol/Function.h"
 #include "lldb/Symbol/Symbol.h"
 #include "lldb/Symbol/SymbolContextScope.h"
+#include "lldb/Symbol/SymbolFile.h"
 #include "lldb/Symbol/Type.h"
 #include "lldb/Symbol/VariableList.h"
 #include "lldb/Target/ABI.h"
@@ -420,10 +421,12 @@
   return m_sc;
 }
 
-VariableList *StackFrame::GetVariableList(bool get_file_globals) {
+VariableList *StackFrame::GetVariableList(bool get_file_globals,
+                                          Status *error_ptr) {
   std::lock_guard<std::recursive_mutex> guard(m_mutex);
   if (m_flags.IsClear(RESOLVED_VARIABLES)) {
     m_flags.Set(RESOLVED_VARIABLES);
+    m_variable_list_sp = std::make_shared<VariableList>();
 
     Block *frame_block = GetFrameBlock();
 
@@ -431,7 +434,6 @@
       const bool get_child_variables = true;
       const bool can_create = true;
       const bool stop_if_child_block_is_inlined_function = true;
-      m_variable_list_sp = std::make_shared<VariableList>();
       frame_block->AppendBlockVariables(can_create, get_child_variables,
                                         stop_if_child_block_is_inlined_function,
                                         [](Variable *v) { return true; },
@@ -455,6 +457,17 @@
     }
   }
 
+  if (error_ptr && m_variable_list_sp->GetSize() == 0) {
+    // Check with the symbol file to check if there is an error for why we
+    // don't have variables that the user might need to know about.
+    GetSymbolContext(eSymbolContextEverything);
+    if (m_sc.module_sp) {
+      SymbolFile *sym_file = m_sc.module_sp->GetSymbolFile();
+      if (sym_file)
+        *error_ptr = sym_file->GetFrameVariableError(*this);
+    }
+  }
+
   return m_variable_list_sp.get();
 }
 
@@ -1147,16 +1160,16 @@
                                            DynamicValueType use_dynamic) {
   ValueObjectSP valobj_sp;
   { // Scope for stack frame mutex.  We need to drop this mutex before we figure
-    // out the dynamic value.  That will require converting the StackID in the 
-    // VO back to a StackFrame, which will in turn require locking the 
-    // StackFrameList.  If we still hold the StackFrame mutex, we could suffer 
-    // lock inversion against the pattern of getting the StackFrameList and 
+    // out the dynamic value.  That will require converting the StackID in the
+    // VO back to a StackFrame, which will in turn require locking the
+    // StackFrameList.  If we still hold the StackFrame mutex, we could suffer
+    // lock inversion against the pattern of getting the StackFrameList and
     // then the stack frame, which is fairly common.
     std::lock_guard<std::recursive_mutex> guard(m_mutex);
     if (IsHistorical()) {
       return valobj_sp;
     }
-    VariableList *var_list = GetVariableList(true);
+    VariableList *var_list = GetVariableList(true, nullptr);
     if (var_list) {
       // Make sure the variable is a frame variable
       const uint32_t var_idx = var_list->FindIndexForVariable(variable_sp.get());
@@ -1698,7 +1711,7 @@
   }
 
   const bool get_file_globals = false;
-  VariableList *variables = GetVariableList(get_file_globals);
+  VariableList *variables = GetVariableList(get_file_globals, nullptr);
 
   if (!variables) {
     return ValueObjectSP();
Index: lldb/source/Symbol/Variable.cpp
===================================================================
--- lldb/source/Symbol/Variable.cpp
+++ lldb/source/Symbol/Variable.cpp
@@ -578,7 +578,8 @@
       if (frame) {
         const bool get_file_globals = true;
 
-        VariableList *variable_list = frame->GetVariableList(get_file_globals);
+        VariableList *variable_list = frame->GetVariableList(get_file_globals,
+                                                             nullptr);
 
         if (variable_list) {
           for (const VariableSP &var_sp : *variable_list)
@@ -674,7 +675,7 @@
           const bool get_file_globals = true;
 
           VariableList *variable_list =
-              frame->GetVariableList(get_file_globals);
+              frame->GetVariableList(get_file_globals, nullptr);
 
           if (!variable_list)
             break;
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
@@ -101,6 +101,10 @@
       const lldb_private::SourceLocationSpec &src_location_spec,
       lldb::SymbolContextItem resolve_scope,
       lldb_private::SymbolContextList &sc_list) override;
+
+  lldb_private::Status
+  GetFrameVariableError(lldb_private::StackFrame &frame) override;
+
   void
   FindGlobalVariables(lldb_private::ConstString name,
                       const lldb_private::CompilerDeclContext &parent_decl_ctx,
@@ -168,6 +172,7 @@
     lldb_private::FileSpec so_file;
     lldb_private::ConstString oso_path;
     llvm::sys::TimePoint<> oso_mod_time;
+    lldb_private::Status oso_load_error;
     OSOInfoSP oso_sp;
     lldb::CompUnitSP compile_unit_sp;
     uint32_t first_symbol_index = UINT32_MAX;
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -31,6 +31,8 @@
 #include "lldb/Symbol/VariableList.h"
 #include "llvm/Support/ScopedPrinter.h"
 
+#include "lldb/Target/StackFrame.h"
+
 #include "LogChannelDWARF.h"
 #include "SymbolFileDWARF.h"
 
@@ -418,12 +420,14 @@
         // modification timestamp, since it will never match.
         if (comp_unit_info->oso_mod_time != llvm::sys::TimePoint<>() &&
             oso_mod_time != comp_unit_info->oso_mod_time) {
-          obj_file->GetModule()->ReportError(
-              "debug map object file '%s' has changed (actual time is "
-              "%s, debug map time is %s"
-              ") since this executable was linked, file will be ignored",
-              oso_file.GetPath().c_str(), llvm::to_string(oso_mod_time).c_str(),
-              llvm::to_string(comp_unit_info->oso_mod_time).c_str());
+          comp_unit_info->oso_load_error.SetErrorStringWithFormat(
+              "debug map object file \"%s\" changed (actual: 0x%8.8x, debug "
+              "map: 0x%8.8x) since this executable was linked, debug info "
+              "will not be loaded", oso_file.GetPath().c_str(),
+              (uint32_t)llvm::sys::toTimeT(oso_mod_time),
+              (uint32_t)llvm::sys::toTimeT(comp_unit_info->oso_mod_time));
+          obj_file->GetModule()->ReportError("%s",
+              comp_unit_info->oso_load_error.AsCString());
           return nullptr;
         }
 
@@ -432,6 +436,10 @@
 
         if (!ObjectFile::SplitArchivePathWithObject(oso_path, oso_file,
                                                     oso_object, must_exist)) {
+          comp_unit_info->oso_load_error.SetErrorStringWithFormat(
+              "debug map object file \"%s\" containing debug info does not "
+              "exist, debug info will not be loaded",
+              comp_unit_info->oso_path.GetCString());
           return nullptr;
         }
       }
@@ -454,6 +462,20 @@
           obj_file->GetModule(), GetCompUnitInfoIndex(comp_unit_info), oso_file,
           oso_arch, oso_object ? &oso_object : nullptr, 0,
           oso_object ? comp_unit_info->oso_mod_time : llvm::sys::TimePoint<>());
+
+      if (!comp_unit_info->oso_sp->module_sp || !comp_unit_info->oso_sp->module_sp->GetObjectFile()) {
+        if (oso_object && FileSystem::Instance().Exists(oso_file)) {
+          // If we are loading a .o file from a .a file the "oso_object" will
+          // have a valid value name and if the .a file exists, either the .o
+          // file didn't exist in the .a file or the mod time didn't match.
+          comp_unit_info->oso_load_error.SetErrorStringWithFormat(
+              "\"%s\" object from the \"%s\" archive: "
+              "either the .o file doesn't exist in the archive or the "
+              "modification time (0x%8.8x) of the .o file doesn't match",
+              oso_object.AsCString(), oso_file.GetPath().c_str(),
+              (uint32_t)llvm::sys::toTimeT(comp_unit_info->oso_mod_time));
+        }
+      }
     }
   }
   if (comp_unit_info->oso_sp)
@@ -1430,3 +1452,48 @@
   });
   return oso_modules;
 }
+
+Status SymbolFileDWARFDebugMap::GetFrameVariableError(StackFrame &frame) {
+  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
+
+  // We need to make sure that our PC value from the frame matches the module
+  // for this object file since we will lookup the PC file address in the debug
+  // map below.
+  Address pc_addr = frame.GetFrameCodeAddress();
+  if (pc_addr.GetModule() == m_objfile_sp->GetModule()) {
+    Symtab *symtab = m_objfile_sp->GetSymtab();
+    if (symtab) {
+      const DebugMap::Entry *debug_map_entry =
+          m_debug_map.FindEntryThatContains(pc_addr.GetFileAddress());
+      if (debug_map_entry) {
+        Symbol *symbol =
+            symtab->SymbolAtIndex(debug_map_entry->data.GetExeSymbolIndex());
+        if (symbol) {
+          uint32_t oso_idx = 0;
+          CompileUnitInfo *comp_unit_info =
+              GetCompileUnitInfoForSymbolWithID(symbol->GetID(), &oso_idx);
+          if (comp_unit_info) {
+            Module *oso_module = GetModuleByCompUnitInfo(comp_unit_info);
+            if (oso_module) {
+              // Check the .o file's DWARF in case it has an error to display.
+              SymbolFile *oso_sym_file = oso_module->GetSymbolFile();
+              if (oso_sym_file)
+                return oso_sym_file->GetFrameVariableError(frame);
+            }
+            // If we don't have a valid OSO module here, then something went
+            // wrong as we have a symbol for the address in the debug map, but
+            // we weren't able to open the .o file. Display an appropriate
+            // error
+            if (comp_unit_info->oso_load_error.Fail())
+              return comp_unit_info->oso_load_error;
+            else
+              return Status("unable to load debug map object file \"%s\" "
+                            "exist, debug info will not be loaded",
+                            comp_unit_info->oso_path.GetCString());
+          }
+        }
+      }
+    }
+  }
+  return Status();
+}
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -163,6 +163,9 @@
                                 lldb::SymbolContextItem resolve_scope,
                                 lldb_private::SymbolContext &sc) override;
 
+  lldb_private::Status
+  GetFrameVariableError(lldb_private::StackFrame &frame) override;
+
   uint32_t ResolveSymbolContext(
       const lldb_private::SourceLocationSpec &src_location_spec,
       lldb::SymbolContextItem resolve_scope,
@@ -519,6 +522,22 @@
 
   void InitializeFirstCodeAddress();
 
+  /// Get the compile command with options if avaiable in the DWARF.
+  ///
+  /// Some compiler flags can be used to save the compiler command line to the
+  /// DWARF. On Darwin compilers, if you define RC_DEBUG_OPTIONS in the
+  /// environment, you can get the compiler command line saved in each compile
+  /// unit's debug info in the DW_AT_APPLE_flags attribute. On other systems you
+  /// can specify -grecord-command-line to save the command line options that
+  /// get appended to the DW_AT_producer. This function will look for the
+  /// options string and return them if they are found.
+  ///
+  /// \returns
+  ///   Valid string with options if the DW_AT_APPLE_flags attribute is found
+  ///   on the DW_TAG_compile_unit DIE, or if the DW_AT_producer contains
+  ///   compiler options.
+  llvm::Optional<llvm::StringRef> GetCompileCommand(DWARFCompileUnit *dwarf_cu);
+
   lldb::ModuleWP m_debug_map_module_wp;
   SymbolFileDWARFDebugMap *m_debug_map_symfile;
 
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -4121,3 +4121,47 @@
     return m_index->GetIndexTime();
   return {};
 }
+
+llvm::Optional<llvm::StringRef>
+SymbolFileDWARF::GetCompileCommand(DWARFCompileUnit *dwarf_cu) {
+  if (!dwarf_cu)
+    return llvm::None;
+  const DWARFBaseDIE cu_die = dwarf_cu->GetNonSkeletonUnit().GetUnitDIEOnly();
+  if (!cu_die)
+    return llvm::None;
+  // When debug information is tuned for lldb or if we build on Darwin and have
+  // RC_DEBUG_OPTIONS defined in the environment when compiling, or
+  llvm::StringRef command;
+  command = cu_die.GetAttributeValueAsString(DW_AT_APPLE_flags, nullptr);
+  if (!command.empty())
+    return command;
+  // Sometimes with -grecord-command-line the command line options to the
+  // compiler are appended to the normal compiler producer line. We check for
+  // the producer string and also make sure it contains a space and a '-'
+  // character to indicate some options might be in the producer string.
+  command = cu_die.GetAttributeValueAsString(DW_AT_producer, nullptr);
+  if (!command.empty() && command.contains(" -"))
+    return command;
+  return llvm::None;
+}
+
+Status SymbolFileDWARF::GetFrameVariableError(StackFrame &frame) {
+  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
+  CompileUnit *cu = frame.GetSymbolContext(eSymbolContextCompUnit).comp_unit;
+  if (!cu)
+    return Status();
+
+  DWARFCompileUnit *dwarf_cu = GetDWARFCompileUnit(cu);
+  if (!dwarf_cu)
+    return Status();
+
+  llvm::Optional<llvm::StringRef> command = GetCompileCommand(dwarf_cu);
+
+  if (command) {
+    if (command->contains(" -gline-tables-only"))
+      return Status("-gline-tables-only enabled, no variable information is "
+                    "available in debug info for this compile unit");
+  }
+
+  return Status();
+}
Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
===================================================================
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
@@ -866,7 +866,7 @@
   // emit DW_AT_object_pointer
   // for C++ so it hasn't actually been tested.
 
-  VariableList *vars = frame->GetVariableList(false);
+  VariableList *vars = frame->GetVariableList(false, nullptr);
 
   lldb::VariableSP this_var = vars->FindVariable(ConstString("this"));
 
@@ -951,7 +951,7 @@
   // In that case, just look up the "self" variable in the current scope
   // and use its type.
 
-  VariableList *vars = frame->GetVariableList(false);
+  VariableList *vars = frame->GetVariableList(false, nullptr);
 
   lldb::VariableSP self_var = vars->FindVariable(ConstString("self"));
 
Index: lldb/source/Core/IOHandlerCursesGUI.cpp
===================================================================
--- lldb/source/Core/IOHandlerCursesGUI.cpp
+++ lldb/source/Core/IOHandlerCursesGUI.cpp
@@ -5908,7 +5908,7 @@
       if (m_frame_block != frame_block) {
         m_frame_block = frame_block;
 
-        VariableList *locals = frame->GetVariableList(true);
+        VariableList *locals = frame->GetVariableList(true, nullptr);
         if (locals) {
           const DynamicValueType use_dynamic = eDynamicDontRunTarget;
           for (const VariableSP &local_sp : *locals) {
Index: lldb/source/Commands/CommandObjectFrame.cpp
===================================================================
--- lldb/source/Commands/CommandObjectFrame.cpp
+++ lldb/source/Commands/CommandObjectFrame.cpp
@@ -483,9 +483,14 @@
     // might clear the StackFrameList for the thread.  So hold onto a shared
     // pointer to the frame so it stays alive.
 
+    Status error;
     VariableList *variable_list =
-        frame->GetVariableList(m_option_variable.show_globals);
+        frame->GetVariableList(m_option_variable.show_globals, &error);
 
+    if (error.Fail() && (!variable_list || variable_list->GetSize() == 0)) {
+      result.AppendError(error.AsCString());
+
+    }
     VariableSP var_sp;
     ValueObjectSP valobj_sp;
 
Index: lldb/source/API/SBValueList.cpp
===================================================================
--- lldb/source/API/SBValueList.cpp
+++ lldb/source/API/SBValueList.cpp
@@ -7,11 +7,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "lldb/API/SBValueList.h"
+#include "lldb/API/SBError.h"
 #include "lldb/API/SBStream.h"
 #include "lldb/API/SBValue.h"
 #include "lldb/Core/ValueObjectList.h"
 #include "lldb/Utility/Instrumentation.h"
-
+#include "lldb/Utility/Status.h"
 #include <vector>
 
 using namespace lldb;
@@ -27,6 +28,7 @@
     if (this == &rhs)
       return *this;
     m_values = rhs.m_values;
+    m_error = rhs.m_error;
     return *this;
   }
 
@@ -63,8 +65,13 @@
     return lldb::SBValue();
   }
 
+  const Status &GetError() const { return m_error; }
+
+  void SetError(const Status &error) { m_error = error; }
+
 private:
   std::vector<lldb::SBValue> m_values;
+  Status m_error;
 };
 
 SBValueList::SBValueList() { LLDB_INSTRUMENT_VA(this); }
@@ -193,3 +200,15 @@
   CreateIfNeeded();
   return *m_opaque_up;
 }
+
+lldb::SBError SBValueList::GetError() {
+  LLDB_INSTRUMENT_VA(this);
+  SBError sb_error;
+  if (m_opaque_up)
+    sb_error.SetError(m_opaque_up->GetError());
+  return sb_error;
+}
+
+void SBValueList::SetError(const lldb_private::Status &status) {
+  ref().SetError(status);
+}
Index: lldb/source/API/SBFrame.cpp
===================================================================
--- lldb/source/API/SBFrame.cpp
+++ lldb/source/API/SBFrame.cpp
@@ -602,7 +602,8 @@
                 &variable_list);
           if (value_type == eValueTypeVariableGlobal) {
             const bool get_file_globals = true;
-            VariableList *frame_vars = frame->GetVariableList(get_file_globals);
+            VariableList *frame_vars = frame->GetVariableList(get_file_globals,
+                                                              nullptr);
             if (frame_vars)
               frame_vars->AppendVariablesIfUnique(variable_list);
           }
@@ -805,7 +806,10 @@
       frame = exe_ctx.GetFramePtr();
       if (frame) {
         VariableList *variable_list = nullptr;
-        variable_list = frame->GetVariableList(true);
+        Status var_error;
+        variable_list = frame->GetVariableList(true, &var_error);
+        if (var_error.Fail())
+          value_list.SetError(var_error);
         if (variable_list) {
           const size_t num_variables = variable_list->GetSize();
           if (num_variables) {
Index: lldb/packages/Python/lldbsuite/test/lldbtest.py
===================================================================
--- lldb/packages/Python/lldbsuite/test/lldbtest.py
+++ lldb/packages/Python/lldbsuite/test/lldbtest.py
@@ -1411,7 +1411,8 @@
             debug_info=None,
             architecture=None,
             compiler=None,
-            dictionary=None):
+            dictionary=None,
+            make_targets=None):
         """Platform specific way to build binaries."""
         if not architecture and configuration.arch:
             architecture = configuration.arch
@@ -1426,7 +1427,7 @@
 
         module = builder_module()
         command = builder_module().getBuildCommand(debug_info, architecture,
-                compiler, dictionary, testdir, testname)
+                compiler, dictionary, testdir, testname, make_targets)
         if command is None:
             raise Exception("Don't know how to build binary")
 
Index: lldb/packages/Python/lldbsuite/test/builders/builder.py
===================================================================
--- lldb/packages/Python/lldbsuite/test/builders/builder.py
+++ lldb/packages/Python/lldbsuite/test/builders/builder.py
@@ -138,13 +138,14 @@
         return None
 
     def getBuildCommand(self, debug_info, architecture=None, compiler=None,
-            dictionary=None, testdir=None, testname=None):
+            dictionary=None, testdir=None, testname=None, make_targets=None):
         debug_info_args = self._getDebugInfoArgs(debug_info)
         if debug_info_args is None:
             return None
-
+        if make_targets is None:
+            make_targets = ["all"]
         command_parts = [
-            self.getMake(testdir, testname), debug_info_args, ["all"],
+            self.getMake(testdir, testname), debug_info_args, make_targets,
             self.getArchCFlags(architecture), self.getArchSpec(architecture),
             self.getCCSpec(compiler), self.getExtraMakeArgs(),
             self.getSDKRootSpec(), self.getModuleCacheSpec(),
Index: lldb/include/lldb/Target/StackFrame.h
===================================================================
--- lldb/include/lldb/Target/StackFrame.h
+++ lldb/include/lldb/Target/StackFrame.h
@@ -254,9 +254,14 @@
   ///     that are visible to the entire compilation unit (e.g. file
   ///     static in C, globals that are homed in this CU).
   ///
+  /// \param [out] error_ptr
+  ///   If there is an error in the debug information that prevents variables
+  ///   from being fetched. \see SymbolFile::GetFrameVariableError() for full
+  ///   details.
+  ///
   /// \return
   ///     A pointer to a list of variables.
-  VariableList *GetVariableList(bool get_file_globals);
+  VariableList *GetVariableList(bool get_file_globals, Status *error_ptr);
 
   /// Retrieve the list of variables that are in scope at this StackFrame's
   /// pc.
Index: lldb/include/lldb/Symbol/SymbolFile.h
===================================================================
--- lldb/include/lldb/Symbol/SymbolFile.h
+++ lldb/include/lldb/Symbol/SymbolFile.h
@@ -222,6 +222,38 @@
   virtual uint32_t ResolveSymbolContext(const Address &so_addr,
                                         lldb::SymbolContextItem resolve_scope,
                                         SymbolContext &sc) = 0;
+
+  /// Get an error that describes why variables might be missing for a given
+  /// symbol context.
+  ///
+  /// If there is an error in the debug information that prevents variables from
+  /// being fetched, this error will get filled in. If there is no debug
+  /// informaiton, no error should be returned. But if there is debug
+  /// information and something prevents the variables from being available a
+  /// valid error should be returned. Valid cases include:
+  /// - compiler option that removes variables (-gline-tables-only)
+  /// - missing external files
+  ///   - .dwo files in fission are not accessible or missing
+  ///   - .o files on darwin when not using dSYM files that are not accessible
+  ///     or missing
+  /// - mismatched exteral files
+  ///   - .dwo files in fission where the DWO ID doesn't match
+  ///   - .o files on darwin when modification timestamp doesn't match
+  /// - corrupted debug info
+  ///
+  /// \param[in] frame
+  ///   The stack frame to use as a basis for the context to check. The frame
+  ///   address can be used if there is not debug info due to it not being able
+  ///   to be loaded, or if there is a debug info context, like a compile unit,
+  ///   or function, it can be used to track down more information on why
+  ///   variables are missing.
+  ///
+  /// \returns
+  ///   An error specifying why there should have been debug info with variable
+  ///   information but the variables were not able to be resolved.
+  virtual Status GetFrameVariableError(StackFrame &frame) {
+    return Status();
+  }
   virtual uint32_t
   ResolveSymbolContext(const SourceLocationSpec &src_location_spec,
                        lldb::SymbolContextItem resolve_scope,
Index: lldb/include/lldb/API/SBValueList.h
===================================================================
--- lldb/include/lldb/API/SBValueList.h
+++ lldb/include/lldb/API/SBValueList.h
@@ -43,6 +43,33 @@
 
   const lldb::SBValueList &operator=(const lldb::SBValueList &rhs);
 
+  // Get an error for why this list is empty.
+  //
+  // If this list is empty, check for an underlying error in the debug
+  // information that prevented this list from being populated. This is not
+  // meant to return an error if there is no debug information as it is ok for a
+  // value list to be empty and no error should be returned in that case. If the
+  // debug info is for an assembly file or language that doesn't have any
+  // variables, no error should be returned.
+  //
+  // This is designed as a way to let users know when they enable certain
+  // compiler options that enable debug information but provide a degraded
+  // debug information content, like -gline-tables-only, which is a compiler
+  // option that allows users to set file and line breakpoints, but users get
+  // confused when no variables show up during debugging.
+  //
+  // It is also designed to inform a user that debug information might be
+  // available if an external file, like a .dwo file, but that file doesn't
+  // exist or wasn't able to be loaded due to a mismatched ID. When debugging
+  // with fission enabled, the line tables are linked into the main executable,
+  // but if the .dwo or .dwp files are not available or have been modified,
+  // users can get confused if they can stop at a file and line breakpoint but
+  // can't see variables in this case.
+  //
+  // This error can give vital clues to the user about the cause is and allow
+  // the user to fix the issue.
+  lldb::SBError GetError();
+
 protected:
   // only useful for visualizing the pointer or comparing two SBValueLists to
   // see if they are backed by the same underlying Impl.
@@ -68,6 +95,8 @@
   ValueListImpl &ref();
 
   std::unique_ptr<ValueListImpl> m_opaque_up;
+
+  void SetError(const lldb_private::Status &status);
 };
 
 } // namespace lldb
Index: lldb/include/lldb/API/SBError.h
===================================================================
--- lldb/include/lldb/API/SBError.h
+++ lldb/include/lldb/API/SBError.h
@@ -64,6 +64,7 @@
   friend class SBCommunication;
   friend class SBData;
   friend class SBDebugger;
+  friend class SBFile;
   friend class SBHostOS;
   friend class SBPlatform;
   friend class SBProcess;
@@ -73,8 +74,8 @@
   friend class SBThread;
   friend class SBTrace;
   friend class SBValue;
+  friend class SBValueList;
   friend class SBWatchpoint;
-  friend class SBFile;
 
   friend class lldb_private::ScriptInterpreter;
 
Index: lldb/bindings/interface/SBValueList.i
===================================================================
--- lldb/bindings/interface/SBValueList.i
+++ lldb/bindings/interface/SBValueList.i
@@ -102,6 +102,8 @@
     lldb::SBValue
     GetFirstValueByName (const char* name) const;
 
+    lldb::SBError GetError();
+
     %extend {
        %nothreadallow;
        std::string lldb::SBValueList::__str__ (){
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