[LLDB] Check type before creating std::atomic synthetic children (llvm#163176)

From
llvm#163077 (comment):
Currently, `std::atomic<T>` will always use the MSVC STL synthetic
children and summary. When inspecting types from other STLs, the output
would not show any children.

This PR adds a check that `std::atomic` contains `_Storage` to be
classified as coming from MSVC's STL.

Author: Nerixyz

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

@@ -142,7 +142,13 @@ lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
 SyntheticChildrenFrontEnd *
 lldb_private::formatters::LibcxxAtomicSyntheticFrontEndCreator(
     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
-  if (valobj_sp)
+  if (valobj_sp && IsLibCxxAtomic(*valobj_sp))
     return new LibcxxStdAtomicSyntheticFrontEnd(valobj_sp);
   return nullptr;
 }
+
+bool lldb_private::formatters::IsLibCxxAtomic(ValueObject &valobj) {
+  if (auto valobj_sp = valobj.GetNonSyntheticValue())
+    return valobj_sp->GetChildMemberWithName("__a_") != nullptr;
+  return false;
+}

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

@@ -18,6 +18,8 @@
 namespace lldb_private {
 namespace formatters {
 
+bool IsLibCxxAtomic(ValueObject &valobj);
+
 lldb::ValueObjectSP GetLibCxxAtomicValue(ValueObject &valobj);
 
 bool LibCxxAtomicSummaryProvider(ValueObject &valobj, Stream &stream,

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

@@ -89,6 +89,7 @@ MsvcStlVariantSyntheticFrontEndCreator(CXXSyntheticChildren *,
                                        lldb::ValueObjectSP valobj_sp);
 
 // MSVC STL std::atomic<>
+bool IsMsvcStlAtomic(ValueObject &valobj);
 bool MsvcStlAtomicSummaryProvider(ValueObject &valobj, Stream &stream,
                                   const TypeSummaryOptions &options);
 SyntheticChildrenFrontEnd *

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

@@ -83,7 +83,9 @@ llvm::Expected<size_t> lldb_private::formatters::
 lldb_private::SyntheticChildrenFrontEnd *
 lldb_private::formatters::MsvcStlAtomicSyntheticFrontEndCreator(
     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
-  return new MsvcStlAtomicSyntheticFrontEnd(valobj_sp);
+  if (valobj_sp && IsMsvcStlAtomic(*valobj_sp))
+    return new MsvcStlAtomicSyntheticFrontEnd(valobj_sp);
+  return nullptr;
 }
 
 bool lldb_private::formatters::MsvcStlAtomicSummaryProvider(
@@ -100,3 +102,9 @@ bool lldb_private::formatters::MsvcStlAtomicSummaryProvider(
   }
   return false;
 }
+
+bool lldb_private::formatters::IsMsvcStlAtomic(ValueObject &valobj) {
+  if (auto valobj_sp = valobj.GetNonSyntheticValue())
+    return valobj_sp->GetChildMemberWithName("_Storage") != nullptr;
+  return false;
+}

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic-simulators/invalid-atomic/Makefile

@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic-simulators/invalid-atomic/TestDataFormatterInvalidAtomic.py

@@ -0,0 +1,45 @@
+"""
+Test formatting of `std::atomic`s not from any STL
+"""
+
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class InvalidAtomicDataFormatterTestCase(TestBase):
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "Set break point at this line.", lldb.SBFileSpec("main.cpp")
+        )
+
+        self.expect_expr(
+            "a",
+            result_children=[
+                ValueCheck(name="foo", value="1"),
+                ValueCheck(name="bar", value="2"),
+            ],
+        )
+        self.expect_expr(
+            "b",
+            result_children=[
+                ValueCheck(name="foo", value="3"),
+                ValueCheck(name="bar", value="4"),
+            ],
+        )
+
+        self.expect_expr(
+            "c",
+            result_children=[
+                ValueCheck(name="foo", value="5"),
+                ValueCheck(name="bar", value="6"),
+            ],
+        )
+        self.expect_expr(
+            "d",
+            result_children=[
+                ValueCheck(name="foo", value="7"),
+                ValueCheck(name="bar", value="8"),
+            ],
+        )

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic-simulators/invalid-atomic/main.cpp

@@ -0,0 +1,23 @@
+namespace std {
+template <typename T> struct atomic {
+  int foo;
+  int bar;
+};
+
+namespace __1 {
+template <typename T> struct atomic {
+  int foo;
+  int bar;
+};
+} // namespace __1
+} // namespace std
+
+int main() {
+  std::atomic<int> a{1, 2};
+  std::atomic<void> b{3, 4};
+
+  std::__1::atomic<int> c{5, 6};
+  std::__1::atomic<void> d{7, 8};
+
+  return 0; // Set break point at this line.
+}