[LLDB] Add formatters for MSVC STL std::optional (llvm#149545)

Adds synthetic children for `std::optional` from MSVC's STL. Most of the
machinery for `std::optional` is already there.

Towards llvm#24834.

Author: Nerixyz

lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp

@@ -1545,20 +1545,10 @@ static void LoadLibStdcppFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
       "std::bitset synthetic child", "^std::(__debug::)?bitset<.+>(( )?&)?$",
       stl_deref_flags, true);
 
-  AddCXXSynthetic(
-      cpp_category_sp,
-      lldb_private::formatters::LibStdcppOptionalSyntheticFrontEndCreator,
-      "std::optional synthetic child", "^std::optional<.+>(( )?&)?$",
-      stl_deref_flags, true);
-
   AddCXXSummary(cpp_category_sp,
                 lldb_private::formatters::StdlibCoroutineHandleSummaryProvider,
                 "libstdc++ std::coroutine_handle summary provider",
                 libstdcpp_std_coroutine_handle_regex, stl_summary_flags, true);
-  AddCXXSummary(cpp_category_sp,
-                lldb_private::formatters::GenericOptionalSummaryProvider,
-                "libstd++ std::optional summary provider",
-                "^std::optional<.+>(( )?&)?$", stl_summary_flags, true);
 }
 
 static lldb_private::SyntheticChildrenFrontEnd *
@@ -1648,6 +1638,17 @@ GenericForwardListSyntheticFrontEndCreator(CXXSyntheticChildren *children,
       *valobj_sp);
 }
 
+static SyntheticChildrenFrontEnd *
+GenericOptionalSyntheticFrontEndCreator(CXXSyntheticChildren *children,
+                                        lldb::ValueObjectSP valobj_sp) {
+  if (!valobj_sp)
+    return nullptr;
+
+  if (IsMsvcStlOptional(*valobj_sp))
+    return MsvcStlOptionalSyntheticFrontEndCreator(children, valobj_sp);
+  return LibStdcppOptionalSyntheticFrontEndCreator(children, valobj_sp);
+}
+
 /// Load formatters that are formatting types from more than one STL
 static void LoadCommonStlFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
   if (!cpp_category_sp)
@@ -1713,6 +1714,12 @@ static void LoadCommonStlFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
                   "std::forward_list synthetic children",
                   "^std::forward_list<.+>(( )?&)?$", stl_synth_flags, true);
 
+  SyntheticChildren::Flags stl_deref_flags = stl_synth_flags;
+  stl_deref_flags.SetFrontEndWantsDereference();
+  AddCXXSynthetic(cpp_category_sp, GenericOptionalSyntheticFrontEndCreator,
+                  "std::optional synthetic children",
+                  "^std::optional<.+>(( )?&)?$", stl_deref_flags, true);
+
   AddCXXSummary(cpp_category_sp, GenericSmartPointerSummaryProvider,
                 "MSVC STL/libstdc++ std::shared_ptr summary provider",
                 "^std::shared_ptr<.+>(( )?&)?$", stl_summary_flags, true);
@@ -1739,6 +1746,9 @@ static void LoadCommonStlFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
       TypeSummaryImplSP(new ScriptSummaryFormat(
           stl_summary_flags,
           "lldb.formatters.cpp.gnu_libstdcpp.ForwardListSummaryProvider")));
+  AddCXXSummary(cpp_category_sp, GenericOptionalSummaryProvider,
+                "MSVC STL/libstd++ std::optional summary provider",
+                "^std::optional<.+>(( )?&)?$", stl_summary_flags, true);
 }
 
 static void LoadMsvcStlFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {

lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp

@@ -9,6 +9,7 @@
 #include "Generic.h"
 #include "LibCxx.h"
 #include "LibStdcpp.h"
+#include "MsvcStl.h"
 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
 #include "lldb/DataFormatters/FormattersHelpers.h"
 #include "lldb/Target/Target.h"
@@ -32,6 +33,7 @@ class GenericOptionalFrontend : public SyntheticChildrenFrontEnd {
   enum class StdLib {
     LibCxx,
     LibStdcpp,
+    MsvcStl,
   };
 
   GenericOptionalFrontend(ValueObject &valobj, StdLib stdlib);
@@ -77,7 +79,8 @@ lldb::ChildCacheState GenericOptionalFrontend::Update() {
   else if (m_stdlib == StdLib::LibStdcpp) {
     if (ValueObjectSP payload = m_backend.GetChildMemberWithName("_M_payload"))
       engaged_sp = payload->GetChildMemberWithName("_M_engaged");
-  }
+  } else if (m_stdlib == StdLib::MsvcStl)
+    engaged_sp = m_backend.GetChildMemberWithName("_Has_value");
 
   if (!engaged_sp)
     return lldb::ChildCacheState::eRefetch;
@@ -114,7 +117,12 @@ ValueObjectSP GenericOptionalFrontend::GetChildAtIndex(uint32_t _idx) {
     ValueObjectSP candidate = val_sp->GetChildMemberWithName("_M_value");
     if (candidate)
       val_sp = candidate;
-  }
+  } else if (m_stdlib == StdLib::MsvcStl)
+    // Same issue as with LibCxx
+    val_sp = m_backend.GetChildMemberWithName("_Has_value")
+                 ->GetParent()
+                 ->GetChildAtIndex(0)
+                 ->GetChildMemberWithName("_Value");
 
   if (!val_sp)
     return ValueObjectSP();
@@ -143,3 +151,17 @@ SyntheticChildrenFrontEnd *formatters::LibcxxOptionalSyntheticFrontEndCreator(
                                        GenericOptionalFrontend::StdLib::LibCxx);
   return nullptr;
 }
+
+bool formatters::IsMsvcStlOptional(ValueObject &valobj) {
+  if (auto valobj_sp = valobj.GetNonSyntheticValue())
+    return valobj_sp->GetChildMemberWithName("_Has_value") != nullptr;
+  return false;
+}
+
+SyntheticChildrenFrontEnd *formatters::MsvcStlOptionalSyntheticFrontEndCreator(
+    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+  if (valobj_sp)
+    return new GenericOptionalFrontend(
+        *valobj_sp, GenericOptionalFrontend::StdLib::MsvcStl);
+  return nullptr;
+}

lldb/source/Plugins/Language/CPlusPlus/MsvcStl.h

@@ -65,6 +65,12 @@ SyntheticChildrenFrontEnd *
 MsvcStlListSyntheticFrontEndCreator(CXXSyntheticChildren *,
                                     lldb::ValueObjectSP valobj_sp);
 
+// MSVC STL std::optional<>
+bool IsMsvcStlOptional(ValueObject &valobj);
+SyntheticChildrenFrontEnd *
+MsvcStlOptionalSyntheticFrontEndCreator(CXXSyntheticChildren *,
+                                        lldb::ValueObjectSP valobj_sp);
+
 } // namespace formatters
 } // namespace lldb_private
 

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/optional/TestDataFormatterGenericOptional.py

@@ -3,12 +3,9 @@
 from lldbsuite.test.lldbtest import *
 from lldbsuite.test import lldbutil
 
-USE_LIBSTDCPP = "USE_LIBSTDCPP"
-USE_LIBCPP = "USE_LIBCPP"
-
 
 class GenericOptionalDataFormatterTestCase(TestBase):
-    def do_test_with_run_command(self, stdlib_type):
+    def do_test_with_run_command(self):
         """Test that that file and class static variables display correctly."""
 
         # This is the function to remove the custom formats in order to have a
@@ -21,7 +18,6 @@ def cleanup():
 
         self.addTearDownHook(cleanup)
 
-        self.build(dictionary={stdlib_type: "1"})
         self.runCmd("file " + self.getBuildArtifact("a.out"), CURRENT_EXECUTABLE_SET)
 
         bkpt = self.target().FindBreakpointByID(
@@ -100,7 +96,8 @@ def cleanup():
     ## We are skipping gcc version less that 5.1 since this test requires -std=c++17
     @skipIf(compiler="gcc", compiler_version=["<", "5.1"])
     def test_with_run_command_libcpp(self):
-        self.do_test_with_run_command(USE_LIBCPP)
+        self.build(dictionary={"USE_LIBCPP": 1})
+        self.do_test_with_run_command()
 
     @add_test_categories(["libstdcxx"])
     ## Clang 7.0 is the oldest Clang that can reliably parse newer libc++ versions
@@ -109,4 +106,11 @@ def test_with_run_command_libcpp(self):
     ## We are skipping gcc version less that 5.1 since this test requires -std=c++17
     @skipIf(compiler="gcc", compiler_version=["<", "5.1"])
     def test_with_run_command_libstdcpp(self):
-        self.do_test_with_run_command(USE_LIBSTDCPP)
+        self.build(dictionary={"USE_LIBSTDCPP": 1})
+        self.do_test_with_run_command()
+
+    @add_test_categories(["msvcstl"])
+    def test_with_run_command_msvcstl(self):
+        # No flags, because the "msvcstl" category checks that the MSVC STL is used by default.
+        self.build()
+        self.do_test_with_run_command()