https://github.com/Nerixyz created
https://github.com/llvm/llvm-project/pull/149801
Adds synthetic children and a summary provider for `std::atomic` on MSVC's STL.
This currently only supports DWARF because it relies on the template argument.
Once there are PDB tests, this will probably use the return type of some method
like `value()` because template types aren't available there.
Towards #24834.
>From 679f4fae45cb25fbc16fc8117c287122afd219d2 Mon Sep 17 00:00:00 2001
From: Nerixyz <nerix...@outlook.de>
Date: Mon, 21 Jul 2025 13:36:44 +0200
Subject: [PATCH] [LLDB] Add formatters for MSVC STL std::atomic
---
.../Plugins/Language/CPlusPlus/CMakeLists.txt | 1 +
.../Language/CPlusPlus/CPlusPlusLanguage.cpp | 14 +++
.../Plugins/Language/CPlusPlus/MsvcStl.h | 7 ++
.../Language/CPlusPlus/MsvcStlAtomic.cpp | 102 ++++++++++++++++++
.../atomic/TestDataFormatterStdAtomic.py | 6 ++
5 files changed, 130 insertions(+)
create mode 100644 lldb/source/Plugins/Language/CPlusPlus/MsvcStlAtomic.cpp
diff --git a/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
b/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
index 5905d9b9a6d03..ce4e2d6f0f5af 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
+++ b/lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
@@ -34,6 +34,7 @@ add_lldb_library(lldbPluginCPlusPlusLanguage PLUGIN
LibStdcppTuple.cpp
LibStdcppUniquePointer.cpp
MsvcStl.cpp
+ MsvcStlAtomic.cpp
MsvcStlSmartPointer.cpp
MsvcStlTuple.cpp
MsvcStlVector.cpp
diff --git a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
index a0d5e1dfe3227..16b4d55d2db73 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
@@ -1763,6 +1763,9 @@ static void
LoadMsvcStlFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
.SetDontShowValue(false)
.SetShowMembersOneLiner(false)
.SetHideItemNames(false);
+ SyntheticChildren::Flags stl_synth_flags;
+ stl_synth_flags.SetCascades(true).SetSkipPointers(false).SetSkipReferences(
+ false);
using StringElementType = StringPrinter::StringElementType;
@@ -1784,6 +1787,17 @@ static void
LoadMsvcStlFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
stl_summary_flags,
MsvcStlStringSummaryProvider<StringElementType::UTF32>,
"MSVC STL std::u32string summary provider"));
+
+ stl_summary_flags.SetDontShowChildren(false);
+ stl_summary_flags.SetSkipPointers(false);
+
+ AddCXXSynthetic(cpp_category_sp, MsvcStlAtomicSyntheticFrontEndCreator,
+ "MSVC STL std::atomic synthetic children",
+ "^std::atomic<.+>$", stl_synth_flags, true);
+
+ AddCXXSummary(cpp_category_sp, MsvcStlAtomicSummaryProvider,
+ "MSVC STL std::atomic summary provider", "^std::atomic<.+>$",
+ stl_summary_flags, true);
}
static void LoadSystemFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
diff --git a/lldb/source/Plugins/Language/CPlusPlus/MsvcStl.h
b/lldb/source/Plugins/Language/CPlusPlus/MsvcStl.h
index c08eecfdecee7..3ac12c17a96e1 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/MsvcStl.h
+++ b/lldb/source/Plugins/Language/CPlusPlus/MsvcStl.h
@@ -71,6 +71,13 @@ SyntheticChildrenFrontEnd *
MsvcStlOptionalSyntheticFrontEndCreator(CXXSyntheticChildren *,
lldb::ValueObjectSP valobj_sp);
+// MSVC STL std::atomic<>
+bool MsvcStlAtomicSummaryProvider(ValueObject &valobj, Stream &stream,
+ const TypeSummaryOptions &options);
+SyntheticChildrenFrontEnd *
+MsvcStlAtomicSyntheticFrontEndCreator(CXXSyntheticChildren *,
+ lldb::ValueObjectSP valobj_sp);
+
} // namespace formatters
} // namespace lldb_private
diff --git a/lldb/source/Plugins/Language/CPlusPlus/MsvcStlAtomic.cpp
b/lldb/source/Plugins/Language/CPlusPlus/MsvcStlAtomic.cpp
new file mode 100644
index 0000000000000..3ec324577ac76
--- /dev/null
+++ b/lldb/source/Plugins/Language/CPlusPlus/MsvcStlAtomic.cpp
@@ -0,0 +1,102 @@
+//===-- MsvcStlAtomic.cpp
-------------------------------------------------===//
+//
+// 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 "MsvcStl.h"
+
+#include "lldb/DataFormatters/TypeSynthetic.h"
+
+using namespace lldb;
+
+namespace lldb_private {
+namespace formatters {
+
+class MsvcStlAtomicSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+ MsvcStlAtomicSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
+
+ llvm::Expected<uint32_t> CalculateNumChildren() override;
+
+ lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override;
+
+ lldb::ChildCacheState Update() override;
+
+ llvm::Expected<size_t> GetIndexOfChildWithName(ConstString name) override;
+
+private:
+ ValueObject *m_storage = nullptr;
+ CompilerType m_element_type;
+};
+
+} // namespace formatters
+} // namespace lldb_private
+
+lldb_private::formatters::MsvcStlAtomicSyntheticFrontEnd::
+ MsvcStlAtomicSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
+ : SyntheticChildrenFrontEnd(*valobj_sp), m_element_type() {
+ if (valobj_sp)
+ Update();
+}
+
+llvm::Expected<uint32_t> lldb_private::formatters::
+ MsvcStlAtomicSyntheticFrontEnd::CalculateNumChildren() {
+ return m_storage ? 1 : 0;
+}
+
+lldb::ValueObjectSP
+lldb_private::formatters::MsvcStlAtomicSyntheticFrontEnd::GetChildAtIndex(
+ uint32_t idx) {
+ if (idx == 0)
+ return m_storage->Cast(m_element_type)->Clone(ConstString("Value"));
+ return nullptr;
+}
+
+lldb::ChildCacheState
+lldb_private::formatters::MsvcStlAtomicSyntheticFrontEnd::Update() {
+ m_storage = nullptr;
+ m_element_type.Clear();
+
+ ValueObjectSP storage_sp = m_backend.GetChildMemberWithName("_Storage");
+ if (!storage_sp)
+ return lldb::ChildCacheState::eRefetch;
+
+ m_element_type = m_backend.GetCompilerType().GetTypeTemplateArgument(0);
+ if (!m_element_type)
+ return lldb::ChildCacheState::eRefetch;
+
+ m_storage = storage_sp.get();
+ return lldb::ChildCacheState::eRefetch;
+}
+
+llvm::Expected<size_t> lldb_private::formatters::
+ MsvcStlAtomicSyntheticFrontEnd::GetIndexOfChildWithName(ConstString name) {
+ if (name == "Value")
+ return 0;
+ return llvm::createStringError("Type has no child named '%s'",
+ name.AsCString());
+}
+
+lldb_private::SyntheticChildrenFrontEnd *
+lldb_private::formatters::MsvcStlAtomicSyntheticFrontEndCreator(
+ CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+ return new MsvcStlAtomicSyntheticFrontEnd(valobj_sp);
+}
+
+bool lldb_private::formatters::MsvcStlAtomicSummaryProvider(
+ ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
+ auto synth_sp = valobj.GetSyntheticValue();
+ if (!synth_sp)
+ return false;
+
+ auto value_sp = synth_sp->GetChildAtIndex(0);
+ std::string summary;
+ if (value_sp->GetSummaryAsCString(summary, options) && !summary.empty()) {
+ stream << summary;
+ return true;
+ }
+ return false;
+}
diff --git
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/atomic/TestDataFormatterStdAtomic.py
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/atomic/TestDataFormatterStdAtomic.py
index 8186e1d66985b..bdf12ca3b86db 100644
---
a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/atomic/TestDataFormatterStdAtomic.py
+++
b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/atomic/TestDataFormatterStdAtomic.py
@@ -67,3 +67,9 @@ def do_test(self):
def test_libcxx(self):
self.build(dictionary={"USE_LIBCPP": 1})
self.do_test()
+
+ @add_test_categories(["msvcstl"])
+ def test_msvcstl(self):
+ # No flags, because the "msvcstl" category checks that the MSVC STL is
used by default.
+ self.build()
+ self.do_test()
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