[Lldb-commits] [lldb] [LLDB] Avoid crashes when inspecting MSVC STL types (PR #140761)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: nerix (Nerixyz)

<details>
<summary>Changes</summary>

When inspecting/printing types from MSVC's STL, LLDB would crash because it assumes these types were from libstdc++. Specifically, `std::shared_ptr` and `std::optional` would crash because of a null pointer dereference. I added a minimal test that tests the types with C++ helpers for libstdc++ (only tests for crashes).

Fixes #<!-- -->120310. This still has one unresolved discussion: What about MS STL types? This is https://github.com/llvm/llvm-project/issues/24834, but there was a bit of discussion in #<!-- -->120310 as well. The main issue is that MSVC's STL uses the same type names as libstdc++ (i.e. neither uses an inline namespace like libc++ for some types).

---
Full diff: https://github.com/llvm/llvm-project/pull/140761.diff


4 Files Affected:

- (modified) lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp (+5-3) 
- (modified) lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp (+1-1) 
- (added) lldb/test/Shell/Process/Windows/msstl_smoke.cpp (+57) 
- (modified) lldb/test/Shell/helper/build.py (+3-3) 


``````````diff
diff --git a/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp b/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp
index b1fdc0fe37763..ed4536cb5c775 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/GenericOptional.cpp
@@ -74,9 +74,11 @@ lldb::ChildCacheState GenericOptionalFrontend::Update() {
 
   if (m_stdlib == StdLib::LibCxx)
     engaged_sp = m_backend.GetChildMemberWithName("__engaged_");
-  else if (m_stdlib == StdLib::LibStdcpp)
-    engaged_sp = m_backend.GetChildMemberWithName("_M_payload")
-                     ->GetChildMemberWithName("_M_engaged");
+  else if (m_stdlib == StdLib::LibStdcpp) {
+    ValueObjectSP payload = m_backend.GetChildMemberWithName("_M_payload");
+    if (payload)
+      engaged_sp = payload->GetChildMemberWithName("_M_engaged");
+  }
 
   if (!engaged_sp)
     return lldb::ChildCacheState::eRefetch;
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
index 02113baf64b8c..54158d9a0d85a 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
@@ -379,7 +379,7 @@ LibStdcppSharedPtrSyntheticFrontEnd::CalculateNumChildren() {
 
 lldb::ValueObjectSP
 LibStdcppSharedPtrSyntheticFrontEnd::GetChildAtIndex(uint32_t idx) {
-  if (idx == 0)
+  if (idx == 0 && m_ptr_obj)
     return m_ptr_obj->GetSP();
   if (idx == 1) {
     if (m_ptr_obj && !m_obj_obj) {
diff --git a/lldb/test/Shell/Process/Windows/msstl_smoke.cpp b/lldb/test/Shell/Process/Windows/msstl_smoke.cpp
new file mode 100644
index 0000000000000..4ae8f4256f24e
--- /dev/null
+++ b/lldb/test/Shell/Process/Windows/msstl_smoke.cpp
@@ -0,0 +1,57 @@
+// clang-format off
+
+// REQUIRES: target-windows
+// RUN: %build --compiler=clang-cl -o %t.exe --std c++20 -- %s
+// RUN: env LLDB_USE_NATIVE_PDB_READER=1 %lldb -f %t.exe -o "b main" -o "run" -o "fr v" -o c | FileCheck %s
+
+#include <bitset>
+#include <coroutine>
+#include <deque>
+#include <forward_list>
+#include <list>
+#include <map>
+#include <memory>
+#include <optional>
+#include <set>
+#include <string>
+#include <tuple>
+#include <unordered_map>
+#include <unordered_set>
+#include <variant>
+#include <vector>
+
+int main() {
+  std::shared_ptr<int> foo;
+  std::weak_ptr<int> weak = foo;
+  std::unique_ptr<int> unique(new int(42));
+  std::optional<int> opt;
+  std::string str = "str";
+  std::string longStr =
+      "string that is long enough such that no SSO can happen";
+  std::wstring wStr = L"wstr";
+  std::wstring longWStr =
+      L"string that is long enough such that no SSO can happen";
+  std::tuple<int, bool, float> tuple{1, false, 4.2};
+  std::coroutine_handle<> coroHandle;
+  std::bitset<16> bitset(123);
+
+  std::map<int, int> map{{1, 2}, {2, 4}, {3, 6}, {4, 8}, {5, 10}};
+  auto mapIt = map.find(3);
+  auto mapItEnd = map.find(9);
+  std::set<int> set{1, 2, 3};
+  std::multimap<int, int> mMap{{1, 2}, {1, 1}, {2, 4}};
+  std::multiset<int> mSet{1, 2, 3};
+
+  std::variant<int, float, std::string, std::monostate> variant;
+  std::list<int> list{1, 2, 3};
+  std::forward_list<int> fwList{1, 2, 3};
+
+  std::unordered_map<int, int> uMap{{1, 2}, {2, 4}, {3, 6}};
+  std::unordered_set<int> uSet{1, 2, 4};
+  std::unordered_multimap<int, int> uMMap{{1, 2}, {1, 1}, {2, 4}};
+  std::unordered_multiset<int> uMSet{1, 1, 2};
+  std::deque<int> deque{1, 2, 3};
+  std::vector<int> vec{1, 2, 3};
+}
+
+// CHECK: Process {{.*}} exited with status = 0 (0x00000000)
diff --git a/lldb/test/Shell/helper/build.py b/lldb/test/Shell/helper/build.py
index b2b8146e88c75..caaa14f90af1c 100755
--- a/lldb/test/Shell/helper/build.py
+++ b/lldb/test/Shell/helper/build.py
@@ -683,14 +683,14 @@ def _get_compilation_command(self, source, obj):
             args.append("-fms-compatibility-version=19")
         args.append("/c")
 
+        if self.std:
+            args.append("/std:" + self.std)
+
         args.append("/Fo" + obj)
         if self.toolchain_type == "clang-cl":
             args.append("--")
         args.append(source)
 
-        if self.std:
-            args.append("/std:" + self.std)
-
         return ("compiling", [source], obj, self.compile_env, args)
 
     def _get_link_command(self):

``````````

</details>


https://github.com/llvm/llvm-project/pull/140761