[Lldb-commits] [lldb] [lldb][Formatters] Consistently unwrap pointer element_type in std::shared_ptr formatters (PR #147340)

[Michael Buch via lldb-commits]

https://github.com/Michael137 created https://github.com/llvm/llvm-project/pull/147340

None

>From dba291d4b0b5ac6e62cfc084340cc0524d15d51c Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Mon, 7 Jul 2025 14:45:59 +0100
Subject: [PATCH] [lldb][Formatters] Consistently unwrap pointer element_type
 in std::shared_ptr formatters

---
 .../lldb/DataFormatters/FormattersHelpers.h        |  5 +++++
 lldb/source/DataFormatters/FormattersHelpers.cpp   | 13 +++++++++++++
 lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp  | 14 +++++++-------
 .../Plugins/Language/CPlusPlus/LibStdcpp.cpp       | 12 ++++++------
 .../shared_ptr/TestDataFormatterStdSharedPtr.py    |  4 ++++
 5 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/lldb/include/lldb/DataFormatters/FormattersHelpers.h b/lldb/include/lldb/DataFormatters/FormattersHelpers.h
index 6a47cf37eac64..c7ce199452e1d 100644
--- a/lldb/include/lldb/DataFormatters/FormattersHelpers.h
+++ b/lldb/include/lldb/DataFormatters/FormattersHelpers.h
@@ -63,6 +63,11 @@ void DumpCxxSmartPtrPointerSummary(Stream &stream, ValueObject &ptr,
 bool ContainerSizeSummaryProvider(ValueObject &valobj, Stream &stream,
                                   const TypeSummaryOptions &options);
 
+/// Return the ValueObjectSP of the underlying pointer member whose type
+/// is a desugared 'std::shared_ptr::element_type *'.
+lldb::ValueObjectSP GetCxxSmartPtrElementPointerType(ValueObject &ptr,
+                                                     ValueObject &container);
+
 Address GetArrayAddressOrPointerValue(ValueObject &valobj);
 
 time_t GetOSXEpoch();
diff --git a/lldb/source/DataFormatters/FormattersHelpers.cpp b/lldb/source/DataFormatters/FormattersHelpers.cpp
index 028fc5da73dc0..104c2ce6f1c0a 100644
--- a/lldb/source/DataFormatters/FormattersHelpers.cpp
+++ b/lldb/source/DataFormatters/FormattersHelpers.cpp
@@ -151,3 +151,16 @@ bool lldb_private::formatters::ContainerSizeSummaryProvider(
   return FormatEntity::FormatStringRef("size=${svar%#}", stream, nullptr,
                                        nullptr, nullptr, &valobj, false, false);
 }
+
+ValueObjectSP lldb_private::formatters::GetCxxSmartPtrElementPointerType(
+    ValueObject &ptr, ValueObject &container) {
+  auto container_type = container.GetCompilerType().GetNonReferenceType();
+  if (!container_type)
+    return nullptr;
+
+  auto arg = container_type.GetTypeTemplateArgument(0);
+  if (!arg)
+    return nullptr;
+
+  return ptr.Cast(arg.GetPointerType());
+}
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
index 3079de4936a85..f73a77836034f 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
@@ -264,11 +264,7 @@ lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::GetChildAtIndex(
 
   if (idx == 1) {
     Status status;
-    auto value_type_sp = valobj_sp->GetCompilerType()
-                             .GetTypeTemplateArgument(0)
-                             .GetPointerType();
-    ValueObjectSP cast_ptr_sp = m_ptr_obj->Cast(value_type_sp);
-    ValueObjectSP value_sp = cast_ptr_sp->Dereference(status);
+    ValueObjectSP value_sp = m_ptr_obj->Dereference(status);
     if (status.Success())
       return value_sp;
   }
@@ -293,7 +289,11 @@ lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::Update() {
   if (!ptr_obj_sp)
     return lldb::ChildCacheState::eRefetch;
 
-  m_ptr_obj = ptr_obj_sp->Clone(ConstString("pointer")).get();
+  auto cast_ptr_sp = GetCxxSmartPtrElementPointerType(*ptr_obj_sp, *valobj_sp);
+  if (!cast_ptr_sp)
+    return lldb::ChildCacheState::eRefetch;
+
+  m_ptr_obj = cast_ptr_sp->Clone(ConstString("pointer")).get();
 
   lldb::ValueObjectSP cntrl_sp(valobj_sp->GetChildMemberWithName("__cntrl_"));
 
@@ -305,7 +305,7 @@ lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::Update() {
 llvm::Expected<size_t>
 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
     GetIndexOfChildWithName(ConstString name) {
-  if (name == "__ptr_" || name == "pointer")
+  if (name == "pointer")
     return 0;
 
   if (name == "object" || name == "$$dereference$$")
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
index 84442273aebd4..d66b8339809be 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
@@ -273,11 +273,7 @@ LibStdcppSharedPtrSyntheticFrontEnd::GetChildAtIndex(uint32_t idx) {
       return nullptr;
 
     Status status;
-    auto value_type_sp = valobj_sp->GetCompilerType()
-                             .GetTypeTemplateArgument(0)
-                             .GetPointerType();
-    ValueObjectSP cast_ptr_sp = m_ptr_obj->Cast(value_type_sp);
-    ValueObjectSP value_sp = cast_ptr_sp->Dereference(status);
+    ValueObjectSP value_sp = m_ptr_obj->Dereference(status);
     if (status.Success())
       return value_sp;
   }
@@ -297,7 +293,11 @@ lldb::ChildCacheState LibStdcppSharedPtrSyntheticFrontEnd::Update() {
   if (!ptr_obj_sp)
     return lldb::ChildCacheState::eRefetch;
 
-  m_ptr_obj = ptr_obj_sp->Clone(ConstString("pointer")).get();
+  auto cast_ptr_sp = GetCxxSmartPtrElementPointerType(*ptr_obj_sp, *valobj_sp);
+  if (!cast_ptr_sp)
+    return lldb::ChildCacheState::eRefetch;
+
+  m_ptr_obj = cast_ptr_sp->Clone(ConstString("pointer")).get();
 
   return lldb::ChildCacheState::eRefetch;
 }
diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/shared_ptr/TestDataFormatterStdSharedPtr.py b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/shared_ptr/TestDataFormatterStdSharedPtr.py
index 8b641c9643958..3d8569da0332e 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/shared_ptr/TestDataFormatterStdSharedPtr.py
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/shared_ptr/TestDataFormatterStdSharedPtr.py
@@ -99,6 +99,10 @@ def do_test(self):
             "wie", type="std::weak_ptr<int>", summary="nullptr strong=2 weak=2"
         )
 
+        self.expect_var_path("si.pointer", type="int *")
+        self.expect_var_path("*si.pointer", type="int", value="47")
+        self.expect_var_path("si.object", type="int", value="47")
+
         self.runCmd("settings set target.experimental.use-DIL true")
         self.expect_var_path("ptr_node->value", value="1")
         self.expect_var_path("ptr_node->next->value", value="2")