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https://github.com/microsoft/STL

MSVC's implementation of the C++ Standard Library.
https://github.com/microsoft/STL

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MSVC's implementation of the C++ Standard Library.

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# Microsoft's C++ Standard Library



This is the official repository for Microsoft's implementation of the C++ Standard Library (also known as the STL),

which ships as part of the MSVC toolset and the Visual Studio IDE.



* Our [Changelog][] tracks which updates to this repository appear in each VS release.

* Our [Status Chart][] displays our overall progress over time.

* Join our [Discord server][].

* [![CI Status Badge][STL-CI-badge]][STL-CI-link] (STL-CI build status)

* [![ASan CI Status Badge][STL-ASan-CI-badge]][STL-ASan-CI-link] (STL-ASan-CI build status)



# What This Repo Is Useful For



If you're a programmer who just wants to use the STL, you **don't** need this repo. Simply install the Visual Studio IDE

and select the "Desktop development with C++" workload.



If you want to participate in the STL's development, welcome! You can report issues, comment on pull requests, and learn

about what we're working on. You can also submit pull requests to fix bugs or add features: see [CONTRIBUTING.md][] for

more information.



Finally, you can take our code and use it in other apps and libraries (according to the terms of our license, like

everything else).



# GitHub Migration Status



We're in the process of moving all of our work on the STL to GitHub. Current status:



* Code: **Done.** Our source code is available under the Apache License v2.0 with LLVM Exception. (See

[LICENSE.txt][] and [NOTICE.txt][] for more information.)



* Build System: **In progress.** We're working on a CMake build system, which is currently capable of building one

flavor of the STL (native desktop). We need to extend this to build all of the flavors required for the MSVC toolset

(e.g. `/clr`, `/clr:pure`, OneCore, Spectre). Until that's done, we're keeping our legacy build system around in the

`stl/msbuild` subdirectory. (We're keeping those files in this repo, even though they're unusable outside of Microsoft,

because they need to be updated whenever source files are added/renamed/deleted. We'll delete the legacy machinery as

soon as possible.)



* Tests: **In progress.** We rely on three test suites: std, tr1, and [libcxx][]. We've partially ported std and tr1,

and fully ported libcxx to run under [lit][] using the various configurations/compilers we test internally.



* Continuous Integration: **In progress.** We've set up Azure Pipelines to validate changes to the repository.

Currently, it builds the STL (native desktop for x86, x64, ARM, and ARM64). Also, it strictly verifies that all of our

files have been formatted with [clang-format][] and follow our other whitespace conventions.



* Contribution Guidelines: **Coming soon.** Working on the STL's code involves following many rules. We have codebase

conventions, Standard requirements, Microsoft-specific requirements, binary compatibility (ABI) requirements, and more.

We're eager to begin accepting features and fixes from the community, but in addition to setting up a CI system, we need

to write down all of the rules that are currently stored in our brains. (The ABI rules may be useful to other C++

libraries.)



* Issues: **In progress.** We're going to use GitHub issues to track all of the things that we need to work on. This

includes C++20 features, [LWG issues][], conformance bugs, performance improvements, and other todos. There are

approximately 200 active bugs in the STL's Microsoft-internal database; we need to manually replicate all of them to

GitHub issues. Currently, the [cxx20 tag][] and [LWG tag][] are done; every remaining work item is tracked by a GitHub

issue. The [bug tag][] and [enhancement tag][] are being populated.



* Plans: **In progress.** We're writing up our [Roadmap][].



# Goals



We're implementing the latest C++ Working Draft, currently [N4981][], which will eventually become the next C++

International Standard. The terms Working Draft (WD) and Working Paper (WP) are interchangeable; we often

informally refer to these drafts as "the Standard" while being aware of the difference. (There are other relevant

Standards; for example, supporting `/std:c++14` and `/std:c++17` involves understanding how the C++14 and C++17

Standards differ from the Working Paper, and we often need to refer to the C Standard Library and ECMAScript regular

expression specifications.)



Our primary goals are conformance, performance, usability, and compatibility.



* Conformance: The Working Paper is a moving target; as features and LWG issue resolutions are added, we need to

implement them. That can involve a lot of work because the STL is required to behave in very specific ways and to

handle users doing very unusual things.



* Performance: The STL needs to be extremely fast at runtime; speed is one of C++'s core strengths and most C++

programs use the STL extensively. As a result, we spend more time on optimization than most general-purpose libraries.

(However, we're wary of changes that improve some scenarios at the expense of others, or changes that make code

significantly more complicated and fragile. That is, there's a "complexity budget" that must be spent carefully.)



* Usability: This includes parts of the programming experience like compiler throughput, diagnostic messages, and

debugging checks. For example, we've extensively marked the STL with `[[nodiscard]]` attributes because this helps

programmers avoid bugs.



* Compatibility: This includes binary compatibility and source compatibility. We're keeping VS 2022 binary-compatible

with VS 2015/2017/2019, which restricts what we can change in VS 2022 updates. (We've found that significant changes

are possible even though other changes are impossible, which we'll be documenting in our Contribution Guidelines soon.)

While there are a few exceptions to this rule (e.g. if a feature is added to the Working Paper, we implement it, and

then the feature is significantly changed before the International Standard is finalized, we reserve the right to break

binary compatibility because `/std:c++latest` offers an experimental preview of such features), binary compatibility

generally overrides all other considerations, even conformance. Source compatibility refers to being able to

successfully recompile user code without changes. We consider source compatibility to be important, but not

all-important; breaking source compatibility can be an acceptable cost if done for the right reasons in the right way

(e.g. in a controlled manner with escape hatches).



# Non-Goals



There are things that we aren't interested in doing with this project, for various reasons (most importantly, we need to

focus development effort on our goals). Some examples:



* Non-goal: Porting to other platforms.



* Non-goal: Adding non-Standard extensions.



* Non-goal: Implementing Technical Specifications. (We're prioritizing features in the Working Paper. Occasionally, we

might implement some or all of a TS, often when we're working on the specification itself.)



If you're proposing a feature to WG21 (the C++ Standardization Committee), you're welcome (and encouraged!) to use our

code as a base for a proof-of-concept implementation. These non-goals simply mean that we're unable to consider pull

requests for a proposed feature until it has been voted into a Working Paper. After that happens, we'll be delighted to

review a production-ready pull request.



# Reporting Issues



You can report STL bugs here, where they'll be directly reviewed by maintainers. You can also report STL bugs through

[Developer Community][], or the VS IDE (Help > Send Feedback > Report a Problem...).



**Please help us** efficiently process bug reports by following these rules:



* Only STL bugs should be reported here. If it's a bug in the compiler, CRT, or IDE, please report it through Developer

Community or Report A Problem. If it's a bug in the Windows SDK, please report it through the [Feedback Hub][hub] app.

If you aren't sure, try to reduce your test case and see if you can eliminate the STL's involvement while still

reproducing the bug.



* You should be reasonably confident that you're looking at an actual implementation bug, instead of undefined behavior

or surprising-yet-Standard behavior. Comparing against other implementations can help (but remember that implementations

can differ while conforming to the Standard); try [Compiler Explorer][]. If you still aren't

sure, ask the nearest C++ expert.



* You should prepare a self-contained command-line test case, ideally as small as possible. We need a source file, a

command line, what happened (e.g. a compiler error, runtime misbehavior), and what you expected to happen. By

"self-contained", we mean that your source file has to avoid including code that we don't have. Ideally, only CRT and

STL headers should be included. If you have to include other MSVC libraries, or the Windows SDK, to trigger an STL bug,

that's okay. But if you need parts of your own source code to trigger the STL bug, you need to extract that for us. (On

Developer Community, we'll accept zipped IDE projects if you have no other way to reproduce a bug, but this is very

time-consuming for us to reduce.)



* A good title is helpful. We prefer "``: Short description of your issue". You don't usually need to

mention `std::` or C++. For example, "``: `is_cute` should be true for `enum class FluffyKittens`".



It's okay if you report an apparent STL bug that turns out to be a compiler bug or surprising-yet-Standard behavior.

Just try to follow these rules, so we can spend more time fixing bugs and implementing features.



# How To Build With The Visual Studio IDE



1. Install Visual Studio 2022 17.11 Preview 3 or later.

    * Select "Windows 11 SDK (10.0.22621.0)" in the VS Installer.

    * We recommend selecting "C++ CMake tools for Windows" in the VS Installer.

    This will ensure that you're using supported versions of CMake and Ninja.

    * Otherwise, install [CMake][] 3.29.0 or later, and [Ninja][] 1.11.0 or later.

    * Make sure [Python][] 3.12 or later is available to CMake.

2. Open Visual Studio, and choose the "Clone or check out code" option. Enter the URL of this repository,

   `https://github.com/microsoft/STL`.

3. Open a terminal in the IDE with `` Ctrl + ` `` (by default) or press on "View" in the top bar, and then "Terminal".

4. In the terminal, invoke `git submodule update --init --progress`

5. Choose the architecture you wish to build in the IDE, and build as you would any other project. All necessary CMake

   settings are set by `CMakePresets.json`.



# How To Build With A Native Tools Command Prompt



1. Install Visual Studio 2022 17.11 Preview 3 or later.

    * Select "Windows 11 SDK (10.0.22621.0)" in the VS Installer.

    * We recommend selecting "C++ CMake tools for Windows" in the VS Installer.

    This will ensure that you're using supported versions of CMake and Ninja.

    * Otherwise, install [CMake][] 3.29.0 or later, and [Ninja][] 1.11.0 or later.

    * Make sure [Python][] 3.12 or later is available to CMake.

2. Open a command prompt.

3. Change directories to a location where you'd like a clone of this STL repository.

4. `git clone https://github.com/microsoft/STL.git --recurse-submodules`



To build the x86 target:



1. Open an "x86 Native Tools Command Prompt for VS 2022 Preview".

2. Change directories to the previously cloned `STL` directory.

3. `cmake --preset x86`

4. `cmake --build --preset x86`



To build the x64 target (recommended):



1. Open an "x64 Native Tools Command Prompt for VS 2022 Preview".

2. Change directories to the previously cloned `STL` directory.

3. `cmake --preset x64`

4. `cmake --build --preset x64`



# How To Consume



Consumption of the built library is largely based on the build system you're using. There are at least 2 directories

you need to hook up. Assuming you built the x64 target with the Visual Studio IDE, with the STL repository cloned to

`C:\Dev\STL`, build outputs will end up at `C:\Dev\STL\out\x64\out`. Ensure that the `inc` directory is searched

for headers, and that `lib\{architecture}` is searched for link libraries, before any defaults supplied by MSVC. The

names of the import and static libraries are the same as those that ship with MSVC. As a result, the compiler `/MD`,

`/MDd`, `/MT`, or `/MTd` switches will work without modification of your build scripts or command-line muscle memory.



Should you choose to use the DLL flavors, the DLLs to deploy are built to `bin\{architecture}`. Note that the DLLs

generated by the CMake build system here have a suffix, defaulting to `_oss`, which distinguishes them from the binaries

that ship with MSVC. That avoids any conflict with the DLLs installed by the [redistributables][] into System32 and

ensures that other components wanting to be a "guest in your process", like print drivers and shell extensions, see the

export surface of the STL they were built with. Otherwise, the "`msvcp140.dll`" you deployed in the same directory as

your .exe would "win" over the versions in System32.



The compiler looks for include directories according to the `INCLUDE` environment variable, and the linker looks for

import library directories according to the `LIB` environment variable, and the Windows loader will (eventually) look

for DLL dependencies according to directories in the `PATH` environment variable.

The build generates a batch script named `set_environment.bat` in the output directory. If you run this script in a VS

Developer Command Prompt, it will insert the proper directories into the `INCLUDE`, `LIB`, and `PATH` environment

variables to ensure that the built headers and libraries are used.



## Complete Example Using x64 DLL Flavor



From an "x64 Native Tools Command Prompt for VS 2022 Preview":



```

C:\Users\username\Desktop>C:\Dev\STL\out\x64\set_environment.bat



C:\Users\username\Desktop>type example.cpp

#include 



int main() {

    std::cout << "Hello STL OSS world!\n";

}



C:\Users\username\Desktop>cl /nologo /EHsc /W4 /WX /MDd /std:c++latest .\example.cpp

example.cpp



C:\Users\username\Desktop>.\example.exe

Hello STL OSS world!



C:\Users\username\Desktop>dumpbin /DEPENDENTS .\example.exe | findstr msvcp

    msvcp140d_oss.dll

```



# How To Run The Tests With A Native Tools Command Prompt



1. Follow either [How To Build With A Native Tools Command Prompt][] or [How To Build With The Visual Studio IDE][].

2. Acquire [Python][] 3.12 or newer and have it on the `PATH` (or run it directly using its absolute or relative path).

3. Have LLVM's `bin` directory on the `PATH` (so `clang-cl.exe` is available).

    * We recommend selecting "C++ Clang tools for Windows" in the VS Installer. This will automatically add LLVM to the

    `PATH` of the x86 and x64 Native Tools Command Prompts, and will ensure that you're using a supported version.

    * Otherwise, use [LLVM's installer][] and choose to add LLVM to your `PATH` during installation.

4. Follow the instructions below.



## Running All The Tests



After configuring and building the project, running `ctest` from the build output directory will run all the tests.

CTest will only display the standard error output of tests that failed. In order to get more details from CTest's

`lit` invocations, run the tests with `ctest -V`.



## Running A Subset Of The Tests



`${PROJECT_BINARY_DIR}\tests\utils\stl-lit\stl-lit.py` can be invoked on a subdirectory of a test suite and will execute

all the tests under that subdirectory. This can mean executing the entirety of a single test suite, running all tests

under a category in libcxx, or running a single test in `std` and `tr1`.



## Examples



These examples assume that your current directory is `C:\Dev\STL\out\x64`.



* This command will run all of the test suites with verbose output.

  + `ctest -V`

* This command will also run all of the test suites.

  + `python tests\utils\stl-lit\stl-lit.py ..\..\llvm-project\libcxx\test ..\..\tests\std ..\..\tests\tr1`

* This command will run all of the std test suite.

  + `python tests\utils\stl-lit\stl-lit.py ..\..\tests\std`

* If you want to run a subset of a test suite, you need to point it to the right place in the sources. The following

will run the single test found under VSO_0000000_any_calling_conventions.

  + `python tests\utils\stl-lit\stl-lit.py ..\..\tests\std\tests\VSO_0000000_any_calling_conventions`

* You can invoke `stl-lit` with any arbitrary subdirectory of a test suite. In libcxx this allows you to have finer

control over what category of tests you would like to run. The following will run all the libcxx map tests.

  + `python tests\utils\stl-lit\stl-lit.py ..\..\llvm-project\libcxx\test\std\containers\associative\map`

* You can also use the `--filter` option to include tests whose names match a regular expression. The following

  command will run tests with "atomic_wait" in their names in both the std and libcxx test suites.

  + `python tests\utils\stl-lit\stl-lit.py ..\..\llvm-project\libcxx\test ..\..\tests\std --filter=atomic_wait`

* There's also a `--filter-out` option to exclude tests matching a regular expression;

  `--filter=iota --filter-out=view` would run tests with names matching "iota" but not "view".



## Interpreting The Results Of Tests



### CTest



When running the tests via CTest, all of the test suites are considered to be a single test. If any single test in a

test suite fails, CTest will simply report that the `stl` test failed.



Example:

```

0% tests passed, 1 tests failed out of 1



Total Test time (real) = 2441.55 sec



The following tests FAILED:

      1 - stl (Failed)

```



The primary utility of CTest in this case is to conveniently invoke `stl-lit.py` with the correct set of arguments.



CTest will output everything that was sent to stderr for each of the failed test suites, which can be used to identify

which individual test within the test suite failed. It can sometimes be helpful to run CTest with the `-V` option in

order to see the stdout of the tests.



### stl-lit



When running the tests directly via the generated `stl-lit.py` script the result of each test will be printed. The

format of each result is `{Result Code}: {Test Suite Name} :: {Test Name}:{Configuration Number}`.



Example:

```

-- Testing: 28 tests, 12 workers --

PASS: tr1 :: tests/cwchar1:01 (1 of 28)

PASS: tr1 :: tests/cwchar1:11 (2 of 28)

PASS: tr1 :: tests/cwchar1:02 (3 of 28)

PASS: tr1 :: tests/cwchar1:03 (4 of 28)

PASS: tr1 :: tests/cwchar1:00 (5 of 28)

PASS: tr1 :: tests/cwchar1:04 (6 of 28)

PASS: tr1 :: tests/cwchar1:05 (7 of 28)

PASS: tr1 :: tests/cwchar1:09 (8 of 28)

PASS: tr1 :: tests/cwchar1:06 (9 of 28)

UNSUPPORTED: tr1 :: tests/cwchar1:20 (10 of 28)

UNSUPPORTED: tr1 :: tests/cwchar1:21 (11 of 28)

UNSUPPORTED: tr1 :: tests/cwchar1:22 (12 of 28)

UNSUPPORTED: tr1 :: tests/cwchar1:23 (13 of 28)

UNSUPPORTED: tr1 :: tests/cwchar1:24 (14 of 28)

PASS: tr1 :: tests/cwchar1:07 (15 of 28)

PASS: tr1 :: tests/cwchar1:08 (16 of 28)

PASS: tr1 :: tests/cwchar1:10 (17 of 28)

PASS: tr1 :: tests/cwchar1:16 (18 of 28)

PASS: tr1 :: tests/cwchar1:17 (19 of 28)

PASS: tr1 :: tests/cwchar1:14 (20 of 28)

PASS: tr1 :: tests/cwchar1:12 (21 of 28)

PASS: tr1 :: tests/cwchar1:13 (22 of 28)

PASS: tr1 :: tests/cwchar1:19 (23 of 28)

PASS: tr1 :: tests/cwchar1:18 (24 of 28)

PASS: tr1 :: tests/cwchar1:15 (25 of 28)

PASS: tr1 :: tests/cwchar1:25 (26 of 28)

PASS: tr1 :: tests/cwchar1:26 (27 of 28)

PASS: tr1 :: tests/cwchar1:27 (28 of 28)



Testing Time: 3.96s

  Expected Passes    : 23

  Unsupported Tests  : 5

```



In the above example, we see that 23 tests succeeded and 5 were unsupported.



### Result Code Values



Our tests use the standard [lit result codes][], and an undocumented result code: `SKIPPED`. For our tests, only the

`PASS`, `XFAIL`, `XPASS`, `FAIL`, `UNSUPPORTED`, and `SKIPPED` result codes are relevant.



The `PASS` and `FAIL` result codes are self-explanatory. We want our tests to `PASS` and not `FAIL`.



The `XPASS` and `XFAIL` result codes are less obvious. `XPASS` is actually a failure result and indicates that we

expected a test to fail but it passed. `XFAIL` is a successful result and indicates that we expected the test to fail

and it did. Typically an `XPASS` result means that the `expected_results.txt` file for the test suite needs to be

modified. If the `XPASS` result is a test legitimately passing, the usual course of action would be to remove a `FAIL`

entry from the `expected_results.txt`. However, some tests from `libcxx` mark themselves as `XFAIL` (meaning they

expect to fail) for features they have added tests for but have yet to implement in `libcxx`. If the STL implements

those features first the tests will begin passing unexpectedly for us and return `XPASS` results. In order to resolve

this it is necessary to add a `PASS` entry to the `expected_results.txt` of the test suite in question.



The `UNSUPPORTED` result code means that the requirements for a test are not met and so it will not be run. Currently,

all tests which use the `/clr` or `/clr:pure` options are unsupported. Also, the `/BE` option is unsupported for x86.



The `SKIPPED` result code indicates that a given test was explicitly skipped by adding a `SKIPPED` entry to the

`expected_results.txt`. A test may be skipped for a number of reasons, which include, but are not limited to:

* being an incorrect test

* taking a very long time to run

* failing or passing for the incorrect reason



### Debugging Individual Tests



While `stl-lit` is super awesome in finding out that *something* is wrong or not even compiling, it is not really

helpful in debugging *what* is going wrong. However, debugging individual tests is rather simple given some additional

steps. Let's assume we want to debug a new feature with tests located in `tests\std\tests\GH_XXXX_meow`.



As always, build the STL from your branch and run the tests:

```

C:\STL\out\x64> ninja

C:\STL\out\x64> python tests\utils\stl-lit\stl-lit.py -v C:\STL\tests\std\tests\GH_XXXX_meow

```



Let's assume one of the tests fails an assert and we want to debug that configuration. `stl-lit` will conveniently print

the build command, which is far too long to provide here in full. The important part is to add the following options to

provide debug symbols: `/Zi /Fdbark.pdb`.



You can replace `bark` with any descriptive name you like. Add these before the `"-link"` option in the command line

and recompile. Example:

```

C:\STL\out\x64>cl "C:\STL\tests\std\tests\GH_XXXX_meow\test.cpp" [... more arguments ...]

"-FeC:\STL\out\x64\tests\std\tests\GH_XXXX_meow\Output\02\GH_XXXX_meow.exe" /Zi /Fdbark.pdb "-link"

[... more arguments ...]

```



You can now start debugging the test via:

```

devenv "C:\STL\out\x64\tests\std\tests\GH_XXXX_meow\Output\02\GH_XXXX_meow.exe"

       "C:\STL\tests\std\tests\GH_XXXX_meow\test.cpp"

```



However, this might not work right away, as Visual Studio may complain about a missing `msvcp140_oss.dll`. The reason

is that the STL builds those and other DLLs itself and we should under no circumstances overwrite the installed ones.

If you are testing one of the configurations with dynamic linkage (`/MD` or `/MDd`) the easiest solution is to add the

build folder to your path:

```

set PATH=C:\STL\out\x64\out\bin\amd64;%PATH%

```



# Benchmarking



For performance-sensitive code – containers, algorithms, and the like –

you may wish to write and/or run benchmarks, and the STL team will likely

run any benchmarks we do have in our PR process. Additionally,

if you are writing a "performance improvement" PR, please add and run benchmarks

to show that the PR does, in fact, improve performance.



The benchmarking code is located in `benchmarks`. Adding a new benchmark is as easy as adding a new file

to `benchmarks/src`, and then adding `add_benchmark( )`

to `benchmarks/CMakeLists.txt`.

You may also modify an existing benchmark file. We use Google's [Benchmark][gbenchmark] library,

so you may find [their documentation][gbenchmark:docs] helpful, and you can also read the existing code

for how _we_ use it.



To run benchmarks, you'll need to first build the STL, then build the benchmarks:



```cmd

cmake --preset x64

cmake --build --preset x64

cmake -B out\bench -S benchmarks -G Ninja -DSTL_BINARY_DIR=out\x64

cmake --build out\bench

```



You can then run your benchmark with:



```cmd

out\bench\benchmark- --benchmark_out= --benchmark_out_format=csv

```



And then you can copy this CSV file into Excel, or another spreadsheet program. For example:



```cmd

out\bench\benchmark-std_copy --benchmark_out=benchmark-std_copy-results.csv --benchmark_out_format=csv

```



If you want to see all the other flags you can pass, run:



```cmd

out\bench\benchmark- --help

```



# Editing And Testing The Debugger Visualizer



### Modify The Visualizer



To modify how components are visualized in the debugger, edit the file `stl\debugger\STL.natvis`. For more information

on how to modify this file, check the [natvis documentation][].



### Test Your Changes



You can add the natvis file to any Visual Studio C++ project if you right-click your project > Add > Existing Item and

select the STL.natvis file. After doing this you should be able to see your changes in a Visual Studio debugging

session.



# Block Diagram



The STL is built atop other compiler support libraries that ship with Windows and Visual Studio, like the UCRT,

VCRuntime, and VCStartup. The following diagram describes the dependencies between those components and their ship

vehicles.



```mermaid

flowchart TB

%%{ init: {"flowchart": {"htmlLabels": true}} }%%

    classDef default text-align:left

    subgraph VisualStudioSubgraph[Visual Studio]

        direction TB

        STLNode("STL

        This repo; provides C++ Standard Library headers, separately

        compiled implementations of most of the iostreams functionality,

        and a few runtime support components like std::exception_ptr.")

        subgraph VCRuntimeSubgraph[VCRuntime]

            direction TB

            VCStartupNode("VCStartup

            Provides compiler support mechanisms that

            live in each binary; such as machinery to

            call constructors and destructors for global

            variables, the entry point, and the /GS cookie.



            Merged into static and import libraries of VCRuntime.")

            VCRuntimeNode("VCRuntime

            Provides compiler support mechanisms that can be

            shared between binaries; code that the compiler calls

            on your behalf, such as the C++ exception handling

            runtime, string.h intrinsics, math intrinsics, and

            declarations for CPU-vendor-specific intrinsics.")

        end

    end

    subgraph WindowsSDKSubgraph[Windows SDK]

        UniversalCRTNode("Universal CRT

        Windows component that provides C library support, such as printf,

        C locales, and some POSIX-like shims for the Windows API, like _stat.")

    end

    STLNode ==> VCRuntimeSubgraph & UniversalCRTNode

    VCStartupNode ==> VCRuntimeNode ==> UniversalCRTNode

```



# Contributing



This project welcomes contributions and suggestions. Most contributions require you to agree to a

Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us

the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.



When you submit a pull request, a CLA bot will automatically determine whether you need to provide

a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions

provided by the bot. You will only need to do this once across all repos using our CLA.



See [CONTRIBUTING.md][] for more information.



# Code Of Conduct



This project has adopted the [Microsoft Open Source Code of Conduct][].



See [CODE_OF_CONDUCT.md][] for more information.



# License



Copyright (c) Microsoft Corporation.



SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception



[Changelog]: https://github.com/microsoft/STL/wiki/Changelog

[clang-format]: https://clang.llvm.org/docs/ClangFormat.html

[CMake]: https://cmake.org/download

[CODE_OF_CONDUCT.md]: CODE_OF_CONDUCT.md

[Compiler Explorer]: https://godbolt.org

[CONTRIBUTING.md]: CONTRIBUTING.md

[Developer Community]: https://aka.ms/feedback/report?space=62

[Discord server]: https://discord.gg/XWanNww

[How To Build With A Native Tools Command Prompt]: #how-to-build-with-a-native-tools-command-prompt

[How To Build With The Visual Studio IDE]: #how-to-build-with-the-visual-studio-ide

[LICENSE.txt]: LICENSE.txt

[LLVM's installer]: https://releases.llvm.org/download.html

[LWG issues]: https://cplusplus.github.io/LWG/lwg-toc.html

[LWG tag]: https://github.com/microsoft/STL/issues?q=is%3Aopen+is%3Aissue+label%3ALWG

[Microsoft Open Source Code of Conduct]: https://opensource.microsoft.com/codeofconduct/

[N4981]: https://wg21.link/N4981

[NOTICE.txt]: NOTICE.txt

[Ninja]: https://ninja-build.org

[STL-CI-badge]: https://dev.azure.com/vclibs/STL/_apis/build/status%2FSTL-CI?branchName=main "STL-CI"

[STL-CI-link]: https://dev.azure.com/vclibs/STL/_build/latest?definitionId=4&branchName=main

[STL-ASan-CI-badge]: https://dev.azure.com/vclibs/STL/_apis/build/status%2FSTL-ASan-CI?branchName=main "STL-ASan-CI"

[STL-ASan-CI-link]: https://dev.azure.com/vclibs/STL/_build/latest?definitionId=5&branchName=main

[Python]: https://www.python.org/downloads/windows/

[Roadmap]: https://github.com/microsoft/STL/wiki/Roadmap

[Status Chart]: https://microsoft.github.io/STL/

[bug tag]: https://github.com/microsoft/STL/issues?q=is%3Aopen+is%3Aissue+label%3Abug

[cxx20 tag]: https://github.com/microsoft/STL/issues?q=is%3Aopen+is%3Aissue+label%3Acxx20

[enhancement tag]: https://github.com/microsoft/STL/issues?q=is%3Aopen+is%3Aissue+label%3Aenhancement

[gbenchmark]: https://github.com/google/benchmark

[gbenchmark:docs]: https://github.com/google/benchmark/blob/main/docs/user_guide.md

[hub]: https://support.microsoft.com/en-us/help/4021566/windows-10-send-feedback-to-microsoft-with-feedback-hub-app

[libcxx]: https://libcxx.llvm.org

[lit]: https://llvm.org/docs/CommandGuide/lit.html

[lit result codes]: https://llvm.org/docs/CommandGuide/lit.html#test-status-results

[redistributables]: https://learn.microsoft.com/en-US/cpp/windows/latest-supported-vc-redist

[natvis documentation]: https://learn.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects