---
name: Bug Report
about: Report a bug in the STL
title: "`<header>`: Problem"
labels: ''
assignees: ''

---

# Describe the bug
A clear and concise description of what the bug is. Please check that you've
read the guidelines for submitting STL bug reports in `README.md`. If you are
having problems with any component that is not the STL, instructions to get
to the right place are there.

# Command-line test case
```
C:\Temp>type repro.cpp
#include <iostream>

int main() {
    // Replace this program with one demonstrating your actual bug report,
    // along with the following compilation command. Please leave compiler
    // version banners in the output (don't use /nologo), and include output
    // of your test program, if any.
    std::cout << "test failure\n";
}

C:\Temp>cl /EHsc /W4 /WX /std:c++latest .\repro.cpp
Microsoft (R) C/C++ Optimizing Compiler Version 19.36.32522 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

/std:c++latest is provided as a preview of language features from the latest C++
working draft, and we're eager to hear about bugs and suggestions for improvements.
However, note that these features are provided as-is without support, and subject
to changes or removal as the working draft evolves. See
https://go.microsoft.com/fwlink/?linkid=2045807 for details.

repro.cpp
Microsoft (R) Incremental Linker Version 14.36.32522.0
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:repro.exe
repro.obj

C:\Temp>.\repro.exe
test failure
```

# Expected behavior
A clear and concise description of what you expected to happen.
Alternatively, include `static_assert` or `assert` lines in your
test case above whose failure clearly indicates the problem.

# STL version
* Option 1: MSVC Compiler version
  + Example:
    ```
    C:\Temp>cl.exe
    Microsoft (R) C/C++ Optimizing Compiler Version 19.50.35503 for x64
    Copyright (C) Microsoft Corporation.  All rights reserved.

    usage: cl [ option... ] filename... [ /link linkoption... ]
    ```
* Option 2: `_MSVC_STL_UPDATE` value
  + Example:
    ```
    C:\Temp>type meow.cpp
    #include <iostream>
    int main() {
        std::cout << _MSVC_STL_UPDATE << "\n";
    }

    C:\Temp>cl /EHsc /nologo /W4 meow.cpp && meow
    meow.cpp
    202507
    ```
* Option 3: git commit hash
  + Example:
    ```
    https://github.com/microsoft/STL/commit/219514876ea86491de191ceaa88632616bbc0f19
    ```

# Additional context
Add any other context about the problem here.
