[Expression] Add PersistentExpressionState::GetCompilerTypeFromPersistentDecl

[xiaobai]

Summary

PersistentStateExpressions (e.g. ClangPersistentVariables) have the
ability to define types using expressions that persist throughout the
debugging session. GetCompilerTypeFromPersistentDecl is a useful
operation to have if you need to use any of those persistently declared types,
like in CommandObjectMemory.

This decouples clang from CommandObjectMemory and decouples Plugins from
Commands in general.

[compnerd]

source/Commands/CommandObjectMemory.cpp

479 ↗

(On Diff #202626)

Why is the parameter clang_ast_type and not based on persistent_vars->getKind()?

source/Plugins/ExpressionParser/Clang/ClangPersistentVariables.cpp

58 ↗

(On Diff #202626)

NIT: decl would be a nicer name

[xiaobai]

source/Commands/CommandObjectMemory.cpp

479 ↗

(On Diff #202626)

clang_ast_type is of type CompilerType. I was going to change the name in a follow up but I can do it in this change too.

[labath]

The idea seems right, but I'm not too familiar with this part of the code. Someone else ought to look at this too.

include/lldb/Expression/ExpressionVariable.h

235–236 ↗

(On Diff #202626)

It would be better if this would return Optional(or Expected)<CompilerType>

[xiaobai]

include/lldb/Expression/ExpressionVariable.h

235–236 ↗

(On Diff #202626)

Let me try that out, I'll update this later.

[xiaobai]

Pavel's suggestion
Renamed method from "SetCompilerTypeFromPersistentDecl" to "GetCompilerTypeFromPersistentDecl"

[compnerd]

Would be nice to get someone like @clayborg to chime in, but, I think that @labath also seems to think that this is fine.

source/Commands/CommandObjectMemory.cpp

476 ↗

(On Diff #202805)

I think that auto would be fine given that the GetPersistentExpressionStateForLanguage spells out the return type.

481 ↗

(On Diff #202805)

This seems wrong now. You iterate over all the languages, but always set the clang_ast_type? The type may be a Swift AST type or Clang AST type (or something more exotic like a rust AST type). We should rename that to m_ast_type as per the LLDB style. But, that makes sense to do as a follow up change.

[jingham]

I have no problem with the change in general. However, you've introduced the possibility of name collision between convenience type definition in various languages. So it would be good to run through the persistent DECL's for ALL the supported languages and report collisions. Probably also need to add a -l flag to pick a language?

[xiaobai]

In D62797#1528483, @jingham wrote:

I have no problem with the change in general. However, you've introduced the possibility of name collision between convenience type definition in various languages. So it would be good to run through the persistent DECL's for ALL the supported languages and report collisions. Probably also need to add a -l flag to pick a language?

Hmm, yes that's true. Would you like me to implement that in this patch as well or would you be okay with a follow up patch?

[jingham]

Pretty much the only actual effect of this patch (besides its changes to the dependency graph) are introducing the possibility for ambiguity here. It seems more logical to do it all as one patch.

[xiaobai]

Renamed clang_ast_type to compiler_type to be more general.
Allow for disambiguating by language with the flag -x or --language.

[JDevlieghere]

source/Plugins/ExpressionParser/Clang/ClangPersistentVariables.cpp

66 ↗

(On Diff #203483)

I think there's a matching constructor, which would allow you to get rid of the temporary and do

return CompilerType(ClangASTContext::GetASTContext(&tdecl->getASTContext()),reinterpret_cast<lldb::opaque_compiler_type_t>(const_cast<clang::Type *>(tdecl->getTypeForDecl())));

lldb/trunk/include/lldb/Expression/ExpressionVariable.h

ConstString GetNextPersistentVariableName(Target &target,
                                             llvm::StringRef prefix);
 
   virtual llvm::StringRef
   GetPersistentVariablePrefix(bool is_error = false) const = 0;
 
   virtual void
   RemovePersistentVariable(lldb::ExpressionVariableSP variable) = 0;
 
+  virtual llvm::Optional<CompilerType>
+  GetCompilerTypeFromPersistentDecl(ConstString type_name) = 0;
+
   virtual lldb::addr_t LookupSymbol(ConstString name);
 
   void RegisterExecutionUnit(lldb::IRExecutionUnitSP &execution_unit_sp);
 
 private:
   LLVMCastKind m_kind;
 
   typedef std::set<lldb::IRExecutionUnitSP> ExecutionUnitSet;

lldb/trunk/packages/Python/lldbsuite/test/expression_command/persistent_types/TestPersistentTypes.py

def test_persistent_types(self):
                 '($foobar) 0x',
                 ' = ',
                 "a = 'H'",
                 "b = 'e'",
                 "c = 'l'",
                 "d = 'l'"])  # persistent types are OK to use for memory read
 
         self.expect(
+            "memory read foo -t $foobar -x c",
+            substrs=[
+                '($foobar) 0x',
+                ' = ',
+                "a = 'H'",
+                "b = 'e'",
+                "c = 'l'",
+                "d = 'l'"])  # persistent types are OK to use for memory read
+
+        self.expect(
             "memory read foo -t foobar",
             substrs=[
                 '($foobar) 0x',
                 ' = ',
                 "a = 'H'",
                 "b = 'e'",
                 "c = 'l'",
                 "d = 'l'"],

lldb/trunk/source/Commands/CMakeLists.txt

LINK_LIBS
     lldbCore
     lldbDataFormatters
     lldbExpression
     lldbHost
     lldbInterpreter
     lldbSymbol
     lldbTarget
     lldbUtility
-    lldbPluginExpressionParserClang
 
   LINK_COMPONENTS
     Support
   )

lldb/trunk/source/Commands/CommandObjectMemory.cpp

 //===-- CommandObjectMemory.cpp ---------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#include "clang/AST/Decl.h"
-
 #include "CommandObjectMemory.h"
-#include "Plugins/ExpressionParser/Clang/ClangPersistentVariables.h"
 #include "lldb/Core/Debugger.h"
 #include "lldb/Core/DumpDataExtractor.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/Section.h"
 #include "lldb/Core/ValueObjectMemory.h"
 #include "lldb/DataFormatters/ValueObjectPrinter.h"
+#include "lldb/Expression/ExpressionVariable.h"
 #include "lldb/Host/OptionParser.h"
 #include "lldb/Interpreter/CommandInterpreter.h"
 #include "lldb/Interpreter/CommandReturnObject.h"
 #include "lldb/Interpreter/OptionArgParser.h"
 #include "lldb/Interpreter/OptionGroupFormat.h"
 #include "lldb/Interpreter/OptionGroupOutputFile.h"
 #include "lldb/Interpreter/OptionGroupValueObjectDisplay.h"
+#include "lldb/Interpreter/OptionValueLanguage.h"
 #include "lldb/Interpreter/OptionValueString.h"
 #include "lldb/Interpreter/Options.h"
-#include "lldb/Symbol/ClangASTContext.h"
 #include "lldb/Symbol/SymbolFile.h"
 #include "lldb/Symbol/TypeList.h"
+#include "lldb/Target/Language.h"
 #include "lldb/Target/MemoryHistory.h"
 #include "lldb/Target/MemoryRegionInfo.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/StackFrame.h"
+#include "lldb/Target/Target.h"
 #include "lldb/Target/Thread.h"
 #include "lldb/Utility/Args.h"
 #include "lldb/Utility/DataBufferHeap.h"
 #include "lldb/Utility/DataBufferLLVM.h"
 #include "lldb/Utility/StreamString.h"
 
 #include "lldb/lldb-private.h"
 
 #include <cinttypes>
 #include <memory>
 
 using namespace lldb;
 using namespace lldb_private;
 
 static constexpr OptionDefinition g_read_memory_options[] = {
     // clang-format off
   {LLDB_OPT_SET_1, false, "num-per-line", 'l', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeNumberPerLine, "The number of items per line to display." },
   {LLDB_OPT_SET_2, false, "binary",       'b', OptionParser::eNoArgument,       nullptr, {}, 0, eArgTypeNone,          "If true, memory will be saved as binary. If false, the memory is saved save as an ASCII dump that "
                                                                                                                             "uses the format, size, count and number per line settings." },
-  {LLDB_OPT_SET_3, true , "type",         't', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeNone,          "The name of a type to view memory as." },
+  {LLDB_OPT_SET_3 |
+   LLDB_OPT_SET_4, true , "type",         't', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeName,          "The name of a type to view memory as." },
+  {LLDB_OPT_SET_4, false, "language",     'x', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeLanguage,          "The language of the type to view memory as."},
   {LLDB_OPT_SET_3, false, "offset",       'E', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeCount,         "How many elements of the specified type to skip before starting to display data." },
   {LLDB_OPT_SET_1 |
    LLDB_OPT_SET_2 |
    LLDB_OPT_SET_3, false, "force",        'r', OptionParser::eNoArgument,       nullptr, {}, 0, eArgTypeNone,          "Necessary if reading over target.max-memory-read-size bytes." },
     // clang-format on
 };
 
 class OptionGroupReadMemory : public OptionGroup {
 public:
   OptionGroupReadMemory()
       : m_num_per_line(1, 1), m_output_as_binary(false), m_view_as_type(),
-        m_offset(0, 0) {}
+        m_offset(0, 0), m_language_for_type(eLanguageTypeUnknown) {}
 
   ~OptionGroupReadMemory() override = default;
 
   llvm::ArrayRef<OptionDefinition> GetDefinitions() override {
     return llvm::makeArrayRef(g_read_memory_options);
   }
 
   Status SetOptionValue(uint32_t option_idx, llvm::StringRef option_value,
Status SetOptionValue(uint32_t option_idx, llvm::StringRef option_value,
     case 't':
       error = m_view_as_type.SetValueFromString(option_value);
       break;
 
     case 'r':
       m_force = true;
       break;
 
+    case 'x':
+      error = m_language_for_type.SetValueFromString(option_value);
+      break;
+
     case 'E':
       error = m_offset.SetValueFromString(option_value);
       break;
 
     default:
       error.SetErrorStringWithFormat("unrecognized short option '%c'",
                                      short_option);
       break;
     }
     return error;
   }
 
   void OptionParsingStarting(ExecutionContext *execution_context) override {
     m_num_per_line.Clear();
     m_output_as_binary = false;
     m_view_as_type.Clear();
     m_force = false;
     m_offset.Clear();
+    m_language_for_type.Clear();
   }
 
   Status FinalizeSettings(Target *target, OptionGroupFormat &format_options) {
     Status error;
     OptionValueUInt64 &byte_size_value = format_options.GetByteSizeValue();
     OptionValueUInt64 &count_value = format_options.GetCountValue();
     const bool byte_size_option_set = byte_size_value.OptionWasSet();
     const bool num_per_line_option_set = m_num_per_line.OptionWasSet();
case eFormatVectorOfUInt128:
         count_value = 4;
       break;
     }
     return error;
   }
 
   bool AnyOptionWasSet() const {
     return m_num_per_line.OptionWasSet() || m_output_as_binary ||
-           m_view_as_type.OptionWasSet() || m_offset.OptionWasSet();
+           m_view_as_type.OptionWasSet() || m_offset.OptionWasSet() ||
+           m_language_for_type.OptionWasSet();
   }
 
   OptionValueUInt64 m_num_per_line;
   bool m_output_as_binary;
   OptionValueString m_view_as_type;
   bool m_force;
   OptionValueUInt64 m_offset;
+  OptionValueLanguage m_language_for_type;
 };
 
 // Read memory from the inferior process
 class CommandObjectMemoryRead : public CommandObjectParsed {
 public:
   CommandObjectMemoryRead(CommandInterpreter &interpreter)
       : CommandObjectParsed(
             interpreter, "memory read",
if ((argc == 0 && m_next_addr == LLDB_INVALID_ADDRESS) || argc > 2) {
                                    "an optional end address expression.\n",
                                    m_cmd_name.c_str());
       result.AppendRawWarning("Expressions should be quoted if they contain "
                               "spaces or other special characters.\n");
       result.SetStatus(eReturnStatusFailed);
       return false;
     }
 
-    CompilerType clang_ast_type;
+    CompilerType compiler_type;
     Status error;
 
     const char *view_as_type_cstr =
         m_memory_options.m_view_as_type.GetCurrentValue();
     if (view_as_type_cstr && view_as_type_cstr[0]) {
       // We are viewing memory as a type
 
       const bool exact_match = false;
#undef ALL_KEYWORDS
       ModuleSP search_first;
       if (frame) {
         search_first = frame->GetSymbolContext(eSymbolContextModule).module_sp;
       }
       target->GetImages().FindTypes(search_first.get(), lookup_type_name,
                                     exact_match, 1, searched_symbol_files,
                                     type_list);
 
-      if (type_list.GetSize() == 0 && lookup_type_name.GetCString() &&
-          *lookup_type_name.GetCString() == '$') {
-        if (ClangPersistentVariables *persistent_vars =
-                llvm::dyn_cast_or_null<ClangPersistentVariables>(
-                    target->GetPersistentExpressionStateForLanguage(
-                        lldb::eLanguageTypeC))) {
-          clang::TypeDecl *tdecl = llvm::dyn_cast_or_null<clang::TypeDecl>(
-              persistent_vars->GetPersistentDecl(
-                  ConstString(lookup_type_name)));
-
-          if (tdecl) {
-            clang_ast_type.SetCompilerType(
-                ClangASTContext::GetASTContext(&tdecl->getASTContext()),
-                reinterpret_cast<lldb::opaque_compiler_type_t>(
-                    const_cast<clang::Type *>(tdecl->getTypeForDecl())));
-          }
+      if (type_list.GetSize() == 0 && lookup_type_name.GetCString()) {
+        LanguageType language_for_type =
+            m_memory_options.m_language_for_type.GetCurrentValue();
+        std::set<LanguageType> languages_to_check;
+        if (language_for_type != eLanguageTypeUnknown) {
+          languages_to_check.insert(language_for_type);
+        } else {
+          languages_to_check = Language::GetSupportedLanguages();
+        }
+
+        std::set<CompilerType> user_defined_types;
+        for (auto lang : languages_to_check) {
+          if (auto *persistent_vars =
+                  target->GetPersistentExpressionStateForLanguage(lang)) {
+            if (llvm::Optional<CompilerType> type =
+                    persistent_vars->GetCompilerTypeFromPersistentDecl(
+                        lookup_type_name)) {
+              user_defined_types.emplace(*type);
+            }
+          }
+        }
+
+        if (user_defined_types.size() > 1) {
+          result.AppendErrorWithFormat(
+              "Mutiple types found matching raw type '%s', please disambiguate "
+              "by specifying the language with -x",
+              lookup_type_name.GetCString());
+          result.SetStatus(eReturnStatusFailed);
+          return false;
+
+        if (user_defined_types.size() == 1) {
+          compiler_type = *user_defined_types.begin();
         }
       }
 
-      if (!clang_ast_type.IsValid()) {
+      if (!compiler_type.IsValid()) {
         if (type_list.GetSize() == 0) {
           result.AppendErrorWithFormat("unable to find any types that match "
                                        "the raw type '%s' for full type '%s'\n",
                                        lookup_type_name.GetCString(),
                                        view_as_type_cstr);
           result.SetStatus(eReturnStatusFailed);
           return false;
         } else {
           TypeSP type_sp(type_list.GetTypeAtIndex(0));
-          clang_ast_type = type_sp->GetFullCompilerType();
+          compiler_type = type_sp->GetFullCompilerType();
         }
       }
 
       while (pointer_count > 0) {
-        CompilerType pointer_type = clang_ast_type.GetPointerType();
+        CompilerType pointer_type = compiler_type.GetPointerType();
         if (pointer_type.IsValid())
-          clang_ast_type = pointer_type;
+          compiler_type = pointer_type;
         else {
           result.AppendError("unable make a pointer type\n");
           result.SetStatus(eReturnStatusFailed);
           return false;
         }
         --pointer_count;
       }
 
-      llvm::Optional<uint64_t> size = clang_ast_type.GetByteSize(nullptr);
+      llvm::Optional<uint64_t> size = compiler_type.GetByteSize(nullptr);
       if (!size) {
         result.AppendErrorWithFormat(
             "unable to get the byte size of the type '%s'\n",
             view_as_type_cstr);
         result.SetStatus(eReturnStatusFailed);
         return false;
       }
       m_format_options.GetByteSizeValue() = *size;
#undef ALL_KEYWORDS
 
     lldb::addr_t addr;
     size_t total_byte_size = 0;
     if (argc == 0) {
       // Use the last address and byte size and all options as they were if no
       // options have been set
       addr = m_next_addr;
       total_byte_size = m_prev_byte_size;
-      clang_ast_type = m_prev_clang_ast_type;
+      compiler_type = m_prev_compiler_type;
       if (!m_format_options.AnyOptionWasSet() &&
           !m_memory_options.AnyOptionWasSet() &&
           !m_outfile_options.AnyOptionWasSet() &&
           !m_varobj_options.AnyOptionWasSet()) {
         m_format_options = m_prev_format_options;
         m_memory_options = m_prev_memory_options;
         m_outfile_options = m_prev_outfile_options;
         m_varobj_options = m_prev_varobj_options;
if (total_byte_size > max_unforced_size && !m_memory_options.m_force) {
           "Please use --force to override this restriction just once.\n");
       result.AppendErrorWithFormat("or set target.max-memory-read-size if you "
                                    "will often need a larger limit.\n");
       return false;
     }
 
     DataBufferSP data_sp;
     size_t bytes_read = 0;
-    if (clang_ast_type.GetOpaqueQualType()) {
+    if (compiler_type.GetOpaqueQualType()) {
       // Make sure we don't display our type as ASCII bytes like the default
       // memory read
       if (!m_format_options.GetFormatValue().OptionWasSet())
         m_format_options.GetFormatValue().SetCurrentValue(eFormatDefault);
 
-      llvm::Optional<uint64_t> size = clang_ast_type.GetByteSize(nullptr);
+      llvm::Optional<uint64_t> size = compiler_type.GetByteSize(nullptr);
       if (!size) {
         result.AppendError("can't get size of type");
         return false;
       }
       bytes_read = *size * m_format_options.GetCountValue().GetCurrentValue();
 
       if (argc > 0)
         addr = addr + (*size * m_memory_options.m_offset.GetCurrentValue());
#undef ALL_KEYWORDS
     }
 
     m_next_addr = addr + bytes_read;
     m_prev_byte_size = bytes_read;
     m_prev_format_options = m_format_options;
     m_prev_memory_options = m_memory_options;
     m_prev_outfile_options = m_outfile_options;
     m_prev_varobj_options = m_varobj_options;
-    m_prev_clang_ast_type = clang_ast_type;
+    m_prev_compiler_type = compiler_type;
 
     StreamFile outfile_stream;
     Stream *output_stream = nullptr;
     const FileSpec &outfile_spec =
         m_outfile_options.GetFile().GetCurrentValue();
 
     std::string path = outfile_spec.GetPath();
     if (outfile_spec) {
if (outfile_spec) {
         result.SetStatus(eReturnStatusFailed);
         return false;
       }
     } else {
       output_stream = &result.GetOutputStream();
     }
 
     ExecutionContextScope *exe_scope = m_exe_ctx.GetBestExecutionContextScope();
-    if (clang_ast_type.GetOpaqueQualType()) {
+    if (compiler_type.GetOpaqueQualType()) {
       for (uint32_t i = 0; i < item_count; ++i) {
         addr_t item_addr = addr + (i * item_byte_size);
         Address address(item_addr);
         StreamString name_strm;
         name_strm.Printf("0x%" PRIx64, item_addr);
         ValueObjectSP valobj_sp(ValueObjectMemory::Create(
-            exe_scope, name_strm.GetString(), address, clang_ast_type));
+            exe_scope, name_strm.GetString(), address, compiler_type));
         if (valobj_sp) {
           Format format = m_format_options.GetFormat();
           if (format != eFormatDefault)
             valobj_sp->SetFormat(format);
 
           DumpValueObjectOptions options(m_varobj_options.GetAsDumpOptions(
               eLanguageRuntimeDescriptionDisplayVerbosityFull, format));
 
#undef ALL_KEYWORDS
   OptionGroupOutputFile m_outfile_options;
   OptionGroupValueObjectDisplay m_varobj_options;
   lldb::addr_t m_next_addr;
   lldb::addr_t m_prev_byte_size;
   OptionGroupFormat m_prev_format_options;
   OptionGroupReadMemory m_prev_memory_options;
   OptionGroupOutputFile m_prev_outfile_options;
   OptionGroupValueObjectDisplay m_prev_varobj_options;
-  CompilerType m_prev_clang_ast_type;
+  CompilerType m_prev_compiler_type;
 };
 
 static constexpr OptionDefinition g_memory_find_option_table[] = {
     // clang-format off
   {LLDB_OPT_SET_1,   true,  "expression",  'e', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeExpression, "Evaluate an expression to obtain a byte pattern."},
   {LLDB_OPT_SET_2,   true,  "string",      's', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeName,       "Use text to find a byte pattern."},
   {LLDB_OPT_SET_ALL, false, "count",       'c', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeCount,      "How many times to perform the search."},
   {LLDB_OPT_SET_ALL, false, "dump-offset", 'o', OptionParser::eRequiredArgument, nullptr, {}, 0, eArgTypeOffset,     "When dumping memory for a match, an offset from the match location to start dumping from."},

lldb/trunk/source/Plugins/ExpressionParser/Clang/ClangPersistentVariables.h

lldb::ExpressionVariableSP CreatePersistentVariable(
       uint32_t addr_byte_size) override;
 
   void RemovePersistentVariable(lldb::ExpressionVariableSP variable) override;
   llvm::StringRef
   GetPersistentVariablePrefix(bool is_error) const override {
     return "$";
   }
 
+  llvm::Optional<CompilerType>
+  GetCompilerTypeFromPersistentDecl(ConstString type_name) override;
+
   void RegisterPersistentDecl(ConstString name, clang::NamedDecl *decl);
 
   clang::NamedDecl *GetPersistentDecl(ConstString name);
 
   void AddHandLoadedClangModule(ClangModulesDeclVendor::ModuleID module) {
     m_hand_loaded_clang_modules.push_back(module);
   }
 

lldb/trunk/source/Plugins/ExpressionParser/Clang/ClangPersistentVariables.cpp

 //===-- ClangPersistentVariables.cpp ----------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "ClangPersistentVariables.h"
 
 #include "lldb/Core/Value.h"
+#include "lldb/Symbol/ClangASTContext.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Utility/DataExtractor.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/StreamString.h"
 
 #include "clang/AST/Decl.h"
 
 #include "llvm/ADT/StringMap.h"
void ClangPersistentVariables::RemovePersistentVariable(
   if (*name != '$')
     return;
   name++;
 
   if (strtoul(name, nullptr, 0) == m_next_persistent_variable_id - 1)
     m_next_persistent_variable_id--;
 }
 
+llvm::Optional<CompilerType>
+ClangPersistentVariables::GetCompilerTypeFromPersistentDecl(
+    ConstString type_name) {
+  CompilerType compiler_type;
+  if (clang::TypeDecl *tdecl = llvm::dyn_cast_or_null<clang::TypeDecl>(
+          GetPersistentDecl(type_name))) {
+    compiler_type.SetCompilerType(
+        ClangASTContext::GetASTContext(&tdecl->getASTContext()),
+        reinterpret_cast<lldb::opaque_compiler_type_t>(
+            const_cast<clang::Type *>(tdecl->getTypeForDecl())));
+    return compiler_type;
+  }
+  return llvm::None;
+}
+
 void ClangPersistentVariables::RegisterPersistentDecl(ConstString name,
                                                       clang::NamedDecl *decl) {
   m_persistent_decls.insert(
       std::pair<const char *, clang::NamedDecl *>(name.GetCString(), decl));
 
   if (clang::EnumDecl *enum_decl = llvm::dyn_cast<clang::EnumDecl>(decl)) {
     for (clang::EnumConstantDecl *enumerator_decl : enum_decl->enumerators()) {
       m_persistent_decls.insert(std::pair<const char *, clang::NamedDecl *>(