Add data formatters for go strings and slices.

[ribrdb]

Add tests.

[clayborg]

Enrico should take a look and OK this.

[granata.enrico]

source/Plugins/Language/Go/GoFormatterFunctions.cpp

104

This worries me a little bit

Imagine I have one of these slices with a million elements, and the user gets in and the first thing they do is GetChildAtIndex(750000); then GetChildAtIndex(134621); then GetChildAtIndex(999999)

Now I have allocated one million shared pointers, even though only three are in use

How about std::map<size_t, ValueObjectSP>?

145

I would also do options.SetLanguage(eLanguageTypeGo) here - in case you ever want to do custom escaping, or the StringPrinter gains any further language-specific abilities

source/Plugins/Language/Go/GoLanguage.cpp

79

Any reason why you need to use hardcoded formatters here?

Do strings and slices not have simple type names to match against in Go?

If at all possible, I would prefer to see you add formatters by name instead of hardcoded matches. Hardcoded matches are really meant for cases where the predicate you're trying to express is something a type name or regular expression on type names can't capture.

[Eugene.Zelenko]

source/Plugins/Language/Go/GoFormatterFunctions.cpp

10

Please add include section comments. Same for other sections.

98

Please place destructor near constructor.

source/Plugins/Language/Go/GoLanguage.cpp

49

Please use consistent spacing between methods.

source/Plugins/Language/Go/GoLanguage.h

31

Please use override instead of virtual.

34

Please place constructor before destructor.

65

virtual is not needed. Please run clang-tidy modernize-use-override.

Same for GetPluginVersion().

[Eugene.Zelenko]

source/Plugins/Language/Go/GoFormatterFunctions.h

1

Such comments should be 80 characters long.

15

Please add headers sections comments. Same for other sections. Clang headers should be before LLDB.

source/Plugins/Language/Go/GoLanguage.cpp

11

Please add headers sections comments. GoLanguage.h should be in LLDB headers section.

[Eugene.Zelenko]

I think will be good idea to format code with Clang-format.

See also rL250789 I just committed with similar cleanups for other languages.

[Eugene.Zelenko]

source/Plugins/Language/Go/GoFormatterFunctions.cpp

107

One space should be enough.

[ribrdb]

source/Plugins/Language/Go/GoFormatterFunctions.cpp

10

Which sections? I've seen a couple types of section markers in different files, but it's not consistent. Are there documented recommendations for these?

source/Plugins/Language/Go/GoLanguage.cpp

79

Normal string and slice types can be recognized by name.
But it is easy to create other string or slices with an arbitrary name.
The right thing to do is look at the go kind (for these types and eventually also map and chan). Hardcoded formatters seems like the only way to do this.
I also considered trying to represent this as a base type or typedef, but those both seemed complicated and confusing since they're not things the language itself supports.

[Eugene.Zelenko]

source/Plugins/Language/Go/GoFormatterFunctions.cpp

10

See source/Plugins/Language/Go/GoLanguage.h below. At least this style is consistent across LLDB headers.

[Eugene.Zelenko]

Did you format code with Clang-format? Spaces/no spaces between function names and arguments are inconsistent.

source/Plugins/Language/Go/GoFormatterFunctions.h

30

This header belongs to Other libraries and framework includes.

source/Plugins/Language/Go/GoLanguage.cpp

26

This and next include belong to C++ Includes.

[ribrdb]

Oops, I ran clang-format with the wrong arguments. Ran it again.

[ribrdb]

Is this ready to submit?

[granata.enrico]

I think it's OK to land this, yes

I would still like to think about ways that we can avoid using hardcoded formatters here, but it seems non-trivial and I don't know enough about Go to suggest an obvious solution

cmake/LLDBDependencies.cmake

   lldbPluginDynamicLoaderWindowsDYLD
   
   lldbPluginCPlusPlusLanguage
+  lldbPluginGoLanguage
   lldbPluginObjCLanguage
   lldbPluginObjCPlusPlusLanguage
 

lldb.xcodeproj/project.pbxproj

     9AC703AF117675410086C050 /* SBInstruction.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 9AC703AE117675410086C050 /* SBInstruction.cpp */; };
     9AC703B1117675490086C050 /* SBInstructionList.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 9AC703B0117675490086C050 /* SBInstructionList.cpp */; };
     A36FF33C17D8E94600244D40 /* OptionParser.cpp in Sources */ = {isa = PBXBuildFile; fileRef = A36FF33B17D8E94600244D40 /* OptionParser.cpp */; };
+    AE44FB471BB4BB090033EB62 /* GoLanguage.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AE44FB451BB4BB090033EB62 /* GoLanguage.cpp */; };
+    AE44FB4C1BB4BB540033EB62 /* GoFormatterFunctions.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AE44FB4A1BB4BB540033EB62 /* GoFormatterFunctions.cpp */; };
     AE44FB3E1BB485960033EB62 /* GoLanguageRuntime.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AE44FB3D1BB485960033EB62 /* GoLanguageRuntime.cpp */; };
     AE6897281B94F6DE0018845D /* DWARFASTParserGo.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AE6897261B94F6DE0018845D /* DWARFASTParserGo.cpp */; };
     AE7F56291B8FE418001377A8 /* GoASTContext.cpp in Sources */ = {isa = PBXBuildFile; fileRef = AEFFBA7C1AC4835D0087B932 /* GoASTContext.cpp */; };

     9AF16CC7114086A1007A7B3F /* SBBreakpointLocation.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = SBBreakpointLocation.cpp; path = source/API/SBBreakpointLocation.cpp; sourceTree = "<group>"; };
     A36FF33B17D8E94600244D40 /* OptionParser.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = OptionParser.cpp; sourceTree = "<group>"; };
     A36FF33D17D8E98800244D40 /* OptionParser.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = OptionParser.h; path = include/lldb/Host/OptionParser.h; sourceTree = "<group>"; };
+    AE44FB451BB4BB090033EB62 /* GoLanguage.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = GoLanguage.cpp; path = Language/Go/GoLanguage.cpp; sourceTree = "<group>"; };
+    AE44FB461BB4BB090033EB62 /* GoLanguage.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = GoLanguage.h; path = Language/Go/GoLanguage.h; sourceTree = "<group>"; };
+    AE44FB4A1BB4BB540033EB62 /* GoFormatterFunctions.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = GoFormatterFunctions.cpp; path = Language/Go/GoFormatterFunctions.cpp; sourceTree = "<group>"; };
+    AE44FB4B1BB4BB540033EB62 /* GoFormatterFunctions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = GoFormatterFunctions.h; path = Language/Go/GoFormatterFunctions.h; sourceTree = "<group>"; };
     AE44FB3C1BB4858A0033EB62 /* GoLanguageRuntime.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = GoLanguageRuntime.h; path = Go/GoLanguageRuntime.h; sourceTree = "<group>"; };
     AE44FB3D1BB485960033EB62 /* GoLanguageRuntime.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = GoLanguageRuntime.cpp; path = Go/GoLanguageRuntime.cpp; sourceTree = "<group>"; };
     AE6897261B94F6DE0018845D /* DWARFASTParserGo.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = DWARFASTParserGo.cpp; sourceTree = "<group>"; };

       isa = PBXGroup;
       children = (
         94B6385A1B8FB109004FE1E4 /* CPlusPlus */,
+        AE44FB431BB4BAC20033EB62 /* Go */,
         94B638551B8FAC87004FE1E4 /* ObjC */,
         94B638601B8FB7BE004FE1E4 /* ObjCPlusPlus */,
       );

       name = "SysV-mips";
       sourceTree = "<group>";
     };
+    AE44FB431BB4BAC20033EB62 /* Go */ = {
+      isa = PBXGroup;
+      children = (
+        AE44FB491BB4BB1B0033EB62 /* Formatters */,
+        AE44FB461BB4BB090033EB62 /* GoLanguage.h */,
+        AE44FB451BB4BB090033EB62 /* GoLanguage.cpp */,
+      );
+      name = Go;
+      sourceTree = "<group>";
+    };
+    AE44FB491BB4BB1B0033EB62 /* Formatters */ = {
+      isa = PBXGroup;
+      children = (
+        AE44FB4B1BB4BB540033EB62 /* GoFormatterFunctions.h */,
+        AE44FB4A1BB4BB540033EB62 /* GoFormatterFunctions.cpp */,
+      );
+      name = Formatters;
+      sourceTree = "<group>";
+    };
     AE44FB3B1BB485730033EB62 /* Go */ = {
       isa = PBXGroup;
       children = (

         2689001113353DB600698AC0 /* Watchpoint.cpp in Sources */,
         2689001213353DDE00698AC0 /* CommandObjectApropos.cpp in Sources */,
         4C88BC2A1BA3722B00AA0964 /* Expression.cpp in Sources */,
+        AE44FB4C1BB4BB540033EB62 /* GoFormatterFunctions.cpp in Sources */,
         23042D121976CA1D00621B2C /* PlatformKalimba.cpp in Sources */,
         2689001313353DDE00698AC0 /* CommandObjectArgs.cpp in Sources */,
         2689001413353DDE00698AC0 /* CommandObjectBreakpoint.cpp in Sources */,

         2698699B15E6CBD0002415FF /* OperatingSystemPython.cpp in Sources */,
         947A1D641616476B0017C8D1 /* CommandObjectPlugin.cpp in Sources */,
         2666ADC81B3CB675001FAFD3 /* HexagonDYLDRendezvous.cpp in Sources */,
+        AE44FB471BB4BB090033EB62 /* GoLanguage.cpp in Sources */,
         262ED0081631FA3A00879631 /* OptionGroupString.cpp in Sources */,
         94F48F251A01C687005C0EC6 /* StringPrinter.cpp in Sources */,
         94094C6B163B6F840083A547 /* ValueObjectCast.cpp in Sources */,

source/API/SystemInitializerFull.cpp

 #include "Plugins/InstrumentationRuntime/AddressSanitizer/AddressSanitizerRuntime.h"
 #include "Plugins/JITLoader/GDB/JITLoaderGDB.h"
 #include "Plugins/Language/CPlusPlus/CPlusPlusLanguage.h"
+#include "Plugins/Language/Go/GoLanguage.h"
 #include "Plugins/Language/ObjC/ObjCLanguage.h"
 #include "Plugins/Language/ObjCPlusPlus/ObjCPlusPlusLanguage.h"
 #include "Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.h"

     GoLanguageRuntime::Initialize();
     
     CPlusPlusLanguage::Initialize();
+    GoLanguage::Initialize();
     ObjCLanguage::Initialize();
     ObjCPlusPlusLanguage::Initialize();
 

     RenderScriptRuntime::Terminate();
 
     CPlusPlusLanguage::Terminate();
+    GoLanguage::Terminate();
     ObjCLanguage::Terminate();
     ObjCPlusPlusLanguage::Terminate();
     

source/Plugins/Language/CMakeLists.txt

 add_subdirectory(CPlusPlus)
+add_subdirectory(Go)
 add_subdirectory(ObjC)
 add_subdirectory(ObjCPlusPlus)

source/Plugins/Language/Go/CMakeLists.txt

+add_lldb_library(lldbPluginGoLanguage
+  GoLanguage.cpp
+  GoFormatterFunctions.cpp
+)

source/Plugins/Language/Go/GoFormatterFunctions.h

+//===-- GoFormatterFunctions.h------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_GoFormatterFunctions_h_
+#define liblldb_GoFormatterFunctions_h_
+
+#include <stdint.h>
+#include <time.h>
+
+#include "lldb/lldb-forward.h"
+
+#include "lldb/Core/ConstString.h"
+#include "lldb/DataFormatters/FormatClasses.h"
+#include "lldb/DataFormatters/TypeSynthetic.h"
+#include "lldb/Target/ExecutionContext.h"
+#include "lldb/Target/ObjCLanguageRuntime.h"
+#include "lldb/Target/Target.h"
+
+#include "clang/AST/ASTContext.h"
+
+namespace lldb_private {
+    namespace formatters
+    {
+        
+        bool
+        GoStringSummaryProvider (ValueObject& valobj, Stream& stream, const TypeSummaryOptions& options);
+        
+        SyntheticChildrenFrontEnd* GoSliceSyntheticFrontEndCreator (CXXSyntheticChildren*, lldb::ValueObjectSP);
+
+
+    } // namespace formatters
+} // namespace lldb_private
+
+#endif // liblldb_GoFormatterFunctions_h_

source/Plugins/Language/Go/GoFormatterFunctions.cpp

+//===-- GoFormatterFunctions.cpp---------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <vector>
+
+#include "GoFormatterFunctions.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include "lldb/DataFormatters/StringPrinter.h"
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::formatters;
+
+namespace
+{
+class GoSliceSyntheticFrontEnd : public SyntheticChildrenFrontEnd
+{
+public:
+    GoSliceSyntheticFrontEnd (ValueObject& valobj) : SyntheticChildrenFrontEnd(valobj)
+    {
+        Update();
+    }
+    
+    size_t
+    CalculateNumChildren () override
+    {
+        return m_len;
+    }
+    
+    lldb::ValueObjectSP
+    GetChildAtIndex (size_t idx) override
+    {
+        if (idx < m_len)
+        {
+            if (idx >= m_children.size())
+                m_children.resize(idx + 1);
+            ValueObjectSP& cached = m_children[idx];
+            if (!cached)
+            {
+                StreamString idx_name;
+                idx_name.Printf("[%" PRIu64 "]", (uint64_t)idx);
+                lldb::addr_t object_at_idx = m_base_data_address;
+                object_at_idx += idx * m_type.GetByteSize(nullptr);
+                cached = CreateValueObjectFromAddress(idx_name.GetData(),
+                                                      object_at_idx,
+                                                      m_backend.GetExecutionContextRef(),
+                                                      m_type);
+
+            }
+            return cached;
+        }
+        return ValueObjectSP();
+    }
+    
+    bool
+    Update() override
+    {
+        size_t old_count = m_children.size();
+        
+        ConstString array_const_str("array");
+        ValueObjectSP array_sp = m_backend.GetChildMemberWithName(array_const_str, true);
+        if (!array_sp)
+        {
+            m_children.clear();
+            return old_count == 0;
+        }
+        m_type = array_sp->GetCompilerType().GetPointeeType();
+        m_base_data_address = array_sp->GetPointerValue();
+        
+        ConstString len_const_str("len");
+        ValueObjectSP len_sp = m_backend.GetChildMemberWithName(len_const_str, true);
+        if (len_sp)
+        {
+            m_len = len_sp->GetValueAsUnsigned(0);
+            m_children.clear();
+        }
+        
+        return old_count == m_len;
+    }
+    
+    bool
+    MightHaveChildren () override
+    {
+        return true;
+    }
+    
+    size_t
+    GetIndexOfChildWithName (const ConstString &name) override {
+        return ExtractIndexFromString(name.AsCString());
+    }
+    
+    ~GoSliceSyntheticFrontEnd () override = default;
+
+private:
+    CompilerType m_type;
+    lldb::addr_t m_base_data_address;
+    size_t m_len;
+    std::vector<lldb::ValueObjectSP> m_children;
+};
+
+}  // anonymous namespace
+
+bool
+lldb_private::formatters::GoStringSummaryProvider (ValueObject& valobj, Stream& stream, const TypeSummaryOptions& opts)
+{
+    ProcessSP process_sp = valobj.GetProcessSP();
+    if (!process_sp)
+        return false;
+    
+    if (valobj.IsPointerType())
+    {
+        Error err;
+        ValueObjectSP deref = valobj.Dereference(err);
+        if (!err.Success())
+            return false;
+        return GoStringSummaryProvider(*deref, stream, opts);
+    }
+    
+    ConstString str_name("str");
+    ConstString len_name("len");
+    
+    ValueObjectSP data_sp = valobj.GetChildMemberWithName(str_name, true);
+    ValueObjectSP len_sp = valobj.GetChildMemberWithName(len_name, true);
+    if (!data_sp || !len_sp)
+        return false;
+    bool success;
+    lldb::addr_t valobj_addr = data_sp->GetValueAsUnsigned(0, &success);
+    
+    if (!success)
+        return false;
+    
+    uint64_t length = len_sp->GetValueAsUnsigned(0);
+    if (length == 0)
+    {
+        stream.Printf("\"\"");
+        return true;
+    }
+    
+    StringPrinter::ReadStringAndDumpToStreamOptions options(valobj);
+    options.SetLocation(valobj_addr);
+    options.SetProcessSP(process_sp);
+    options.SetStream(&stream);
+    options.SetSourceSize(length);
+    options.SetNeedsZeroTermination(false);
+    
+    if (!StringPrinter::ReadStringAndDumpToStream<StringPrinter::StringElementType::UTF8>(options))
+    {
+        stream.Printf("Summary Unavailable");
+        return true;
+    }
+    
+    return true;
+}
+
+SyntheticChildrenFrontEnd* lldb_private::formatters::GoSliceSyntheticFrontEndCreator (CXXSyntheticChildren*, lldb::ValueObjectSP valobj_sp)
+{
+    if (!valobj_sp)
+        return nullptr;
+    
+    lldb::ProcessSP process_sp (valobj_sp->GetProcessSP());
+    if (!process_sp)
+        return NULL;
+    return new GoSliceSyntheticFrontEnd(*valobj_sp);
+}

source/Plugins/Language/Go/GoLanguage.h

+//===-- GoLanguage.h --------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_GoLanguage_h_
+#define liblldb_GoLanguage_h_
+
+// C Includes
+// C++ Includes
+#include <vector>
+
+// Other libraries and framework includes
+#include "llvm/ADT/StringRef.h"
+
+// Project includes
+#include "lldb/lldb-private.h"
+#include "lldb/Core/ConstString.h"
+#include "lldb/Target/Language.h"
+
+namespace lldb_private {
+    
+    class GoLanguage :
+    public Language
+    {
+    public:
+        virtual ~GoLanguage() = default;
+        
+        GoLanguage () = default;
+        
+        lldb::LanguageType
+        GetLanguageType () const override
+        {
+            return lldb::eLanguageTypeGo;
+        }
+        
+        HardcodedFormatters::HardcodedSummaryFinder
+        GetHardcodedSummaries () override;
+        
+        HardcodedFormatters::HardcodedSyntheticFinder
+        GetHardcodedSynthetics () override;
+        
+        //------------------------------------------------------------------
+        // Static Functions
+        //------------------------------------------------------------------
+        static void
+        Initialize();
+        
+        static void
+        Terminate();
+        
+        static lldb_private::Language *
+        CreateInstance (lldb::LanguageType language);
+        
+        static lldb_private::ConstString
+        GetPluginNameStatic();
+        
+        //------------------------------------------------------------------
+        // PluginInterface protocol
+        //------------------------------------------------------------------
+        virtual ConstString
+        GetPluginName() override;
+        
+        virtual uint32_t
+        GetPluginVersion() override;
+    };
+    
+} // namespace lldb_private
+
+#endif  // liblldb_GoLanguage_h_

source/Plugins/Language/Go/GoLanguage.cpp

+//===-- GoLanguage.cpp --------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "GoLanguage.h"
+
+#include <string.h>
+
+#include "llvm/ADT/StringRef.h"
+
+#include "lldb/Core/ConstString.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include "lldb/Symbol/GoASTContext.h"
+#include "Plugins/Language/Go/GoFormatterFunctions.h"
+
+#include <functional>
+#include <mutex>
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::formatters;
+
+void
+GoLanguage::Initialize()
+{
+    PluginManager::RegisterPlugin (GetPluginNameStatic(),
+                                   "Go Language",
+                                   CreateInstance);
+}
+
+void
+GoLanguage::Terminate()
+{
+    PluginManager::UnregisterPlugin (CreateInstance);
+}
+
+lldb_private::ConstString
+GoLanguage::GetPluginNameStatic()
+{
+    static ConstString g_name("Go");
+    return g_name;
+}
+
+
+//------------------------------------------------------------------
+// PluginInterface protocol
+//------------------------------------------------------------------
+lldb_private::ConstString
+GoLanguage::GetPluginName()
+{
+    return GetPluginNameStatic();
+}
+
+uint32_t
+GoLanguage::GetPluginVersion()
+{
+    return 1;
+}
+
+//------------------------------------------------------------------
+// Static Functions
+//------------------------------------------------------------------
+Language *
+GoLanguage::CreateInstance (lldb::LanguageType language)
+{
+    if (language == eLanguageTypeGo)
+        return new GoLanguage();
+    return nullptr;
+}
+
+
+HardcodedFormatters::HardcodedSummaryFinder
+GoLanguage::GetHardcodedSummaries ()
+{
+    static std::once_flag g_initialize;
+    static HardcodedFormatters::HardcodedSummaryFinder g_formatters;
+    
+    std::call_once(g_initialize, [] () -> void {
+        g_formatters.push_back(
+                               [](lldb_private::ValueObject& valobj,
+                                  lldb::DynamicValueType,
+                                  FormatManager&) -> TypeSummaryImpl::SharedPointer {
+                                   static CXXFunctionSummaryFormat::SharedPointer formatter_sp(new CXXFunctionSummaryFormat(TypeSummaryImpl::Flags().SetDontShowChildren(true), lldb_private::formatters::GoStringSummaryProvider, "Go string summary provider"));
+                                   if (GoASTContext::IsGoString(valobj.GetCompilerType()))
+                                   {
+                                       return formatter_sp;
+                                   }
+                                   if (GoASTContext::IsGoString(valobj.GetCompilerType().GetPointeeType()))
+                                   {
+                                       return formatter_sp;
+                                   }
+                                   return nullptr;
+                               });
+        g_formatters.push_back(
+                               [](lldb_private::ValueObject& valobj,
+                                  lldb::DynamicValueType,
+                                  FormatManager&) -> TypeSummaryImpl::SharedPointer {
+                                   static  lldb::TypeSummaryImplSP formatter_sp(new StringSummaryFormat(TypeSummaryImpl::Flags().SetHideItemNames(true),                                                                                                                 "(len ${var.len}, cap ${var.cap})"));
+                                   if (GoASTContext::IsGoSlice(valobj.GetCompilerType()))
+                                   {
+                                       return formatter_sp;
+                                   }
+                                   if (GoASTContext::IsGoSlice(valobj.GetCompilerType().GetPointeeType()))
+                                   {
+                                       return formatter_sp;
+                                   }
+                                   return nullptr;
+                               });
+    });
+    return g_formatters;
+}
+
+HardcodedFormatters::HardcodedSyntheticFinder
+GoLanguage::GetHardcodedSynthetics ()
+{
+    static std::once_flag g_initialize;
+    static HardcodedFormatters::HardcodedSyntheticFinder g_formatters;
+    
+    std::call_once(g_initialize, [] () -> void {
+        g_formatters.push_back(
+                               [](lldb_private::ValueObject& valobj,
+                                  lldb::DynamicValueType,
+                                  FormatManager& fmt_mgr) -> SyntheticChildren::SharedPointer {
+                                   static CXXSyntheticChildren::SharedPointer formatter_sp(new CXXSyntheticChildren(SyntheticChildren::Flags(),
+                                                                                                                    "slice synthetic children",
+                                                                                                                    lldb_private::formatters::GoSliceSyntheticFrontEndCreator));
+                                   if (GoASTContext::IsGoSlice(valobj.GetCompilerType()))
+                                   {
+                                       return formatter_sp;
+                                   }
+                                   return nullptr;
+                               });
+    });
+    
+    return g_formatters;
+}
+

source/Plugins/Language/Go/Makefile

+##===- source/Plugins/Language/Go -------------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+LLDB_LEVEL := ../../../..
+LIBRARYNAME := lldbPluginGoLanguage
+BUILD_ARCHIVE = 1
+
+include $(LLDB_LEVEL)/Makefile

source/Plugins/Makefile

   LanguageRuntime/Go/ \
   LanguageRuntime/RenderScript/RenderScriptRuntime \
   Language/CPlusPlus \
+  Language/Go \
   Language/ObjC \
   Language/ObjCPlusPlus \
   DynamicLoader/POSIX-DYLD \

test/lang/go/formatters/TestGoFormatters.py

+"""Test the Go Data Formatter Plugin."""
+
+import os, time
+import unittest2
+import lldb
+import lldbutil
+from lldbtest import *
+
+class TestGoLanguage(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @python_api_test
+    @skipIfFreeBSD # llvm.org/pr24895 triggers assertion failure
+    @skipIfRemote # Not remote test suite ready
+    @no_debug_info_test
+    @skipUnlessGoInstalled
+    def test_go_formatter_plugin(self):
+        """Test go data formatters."""
+        self.buildGo()
+        self.launchProcess()
+        self.check_formatters()
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line numbers to break inside main().
+        self.main_source = "main.go"
+        self.break_line = line_number(self.main_source, '// stop here')
+
+    def launchProcess(self):
+        exe = os.path.join(os.getcwd(), "a.out")
+
+        target = self.dbg.CreateTarget(exe)
+        self.assertTrue(target, VALID_TARGET)
+
+        self.bpt = target.BreakpointCreateByLocation(self.main_source, self.break_line)
+        self.assertTrue(self.bpt, VALID_BREAKPOINT)
+
+        # Now launch the process, and do not stop at entry point.
+        process = target.LaunchSimple (None, None, self.get_process_working_directory())
+
+        self.assertTrue(process, PROCESS_IS_VALID)
+
+        # The stop reason of the thread should be breakpoint.
+        thread_list = lldbutil.get_threads_stopped_at_breakpoint (process, self.bpt)
+
+        # Make sure we stopped at the first breakpoint.
+        self.assertTrue (len(thread_list) != 0, "No thread stopped at our breakpoint.")
+        self.assertTrue (len(thread_list) == 1, "More than one thread stopped at our breakpoint.")
+
+        frame = thread_list[0].GetFrameAtIndex(0)
+        self.assertTrue (frame, "Got a valid frame 0 frame.")
+
+    def check_formatters(self):
+        a = self.frame().FindVariable('a')
+        self.assertEqual('(string) a = "my string"', str(a))
+        b = self.frame().FindVariable('b')
+        self.assertEqual("([]int) b = (len 2, cap 7) {\n  [0] = 0\n  [1] = 0\n}", str(b))
+
+
+if __name__ == '__main__':
+    import atexit
+    lldb.SBDebugger.Initialize()
+    atexit.register(lambda: lldb.SBDebugger.Terminate())
+    unittest2.main()

test/lang/go/formatters/main.go

+package main
+
+import "fmt"
+
+func main() {
+    a := "my string"
+    b := make([]int, 2, 7)
+    fmt.Println(a, b)  // stop here
+}
 No newline at end of file