std::unordered_map values display as "(,)" in hover/variables panel with cppvsdbg debugger

[1anLee]

Environment

• VS Code version: 1.115.0
• cpptools extension: ms-vscode.cpptools 1.31.4
• OS: Windows 11
• Compiler: MSVC (Visual Studio Community 2022, amd64)
• CMake Kit: Visual Studio Community 2022 Release - amd64

Bug Description

When debugging a C++ project built with MSVC (VS2022), std::unordered_map<int, float> values are displayed as (,) in both the hover tooltip and the Variables/Watch panel.

Steps to Reproduce

1. Declare and populate a std::unordered_map<int, float> variable.
2. Start debugging (via CMake Tools, using cppvsdbg).
3. Hover over the variable or expand it in the Variables panel.

Expected Behavior

Each entry should display as [key] = value, e.g. [3] = 0.5.

Actual Behavior

Each entry displays as [3] = (, ).

Additional Notes

• begin()->first and begin()->second both evaluate correctly in the Watch panel, so debug info is intact.
• The issue appears to be that std::pair::DisplayString expressions ({first}, {second}) fail when rendered as part of unordered_map expansion in vsdbg's natvis engine.
• std::vector displays correctly.

[sean-mcmanus]

@IanGrantLee You can see the value by expanding the tree view node, right?

[1anLee]

@sean-mcmanus Yes if I want to check the value I have to expand the element one by one.

[github-actions]

Thank you for reporting this issue. We’ll let you know if we need more information to investigate it. Additionally, if you're working with GDB/LLDB, please note that the code is open source at https://github.com/microsoft/MIEngine/wiki/Contributing-Code . Your contributions are always welcome and appreciated.