base on MSVC's implementation of the C++ Standard Library. # 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 [N4993][], 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 "`<header_name>`: Short description of your issue". You don't usually need to mention `std::` or C++. For example, "`<type_traits>`: `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 17.13 Preview 2 or later. * Select "Windows 11 SDK (10.0.22621.0)" in the VS Installer. * Select "MSVC v143 - VS 2022 C++ ARM64/ARM64EC build tools (Latest)" in the VS Installer if you would like to build the ARM64/ARM64EC target. * Select "MSVC v143 - VS 2022 C++ ARM build tools (Latest)" in the VS Installer if you would like to build the ARM target. * 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][] 3.30.0 or later, and [Ninja][] 1.12.1 or later. * Make sure [Python][] 3.13 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 17.13 Preview 2 or later. * Select "Windows 11 SDK (10.0.22621.0)" in the VS Installer. * Select "MSVC v143 - VS 2022 C++ ARM64/ARM64EC build tools (Latest)" in the VS Installer if you would like to build the ARM64/ARM64EC target. * Select "MSVC v143 - VS 2022 C++ ARM build tools (Latest)" in the VS Installer if you would like to build the ARM target. * 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][] 3.30.0 or later, and [Ninja][] 1.12.1 or later. * Make sure [Python][] 3.13 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` To build the ARM target: 1. `"C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Auxiliary\Build\vcvarsall.bat" x64_arm` * If you installed VS to a non-default location, change this path accordingly. 2. Change directories to the previously cloned `STL` directory. 3. `cmake --preset ARM` 4. `cmake --build --preset ARM` To build the ARM64 target: 1. `"C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Auxiliary\Build\vcvarsall.bat" x64_arm64` * If you installed VS to a non-default location, change this path accordingly. 2. Change directories to the previously cloned `STL` directory. 3. `cmake --preset ARM64` 4. `cmake --build --preset ARM64` To build the ARM64EC target: 1. `"C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Auxiliary\Build\vcvarsall.bat" x64_arm64` * If you installed VS to a non-default location, change this path accordingly. 2. Change directories to the previously cloned `STL` directory. 3. `cmake --preset ARM64EC` 4. `cmake --build --preset ARM64EC` # 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 <iostream> 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][] 3.13 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 The Tests Our tests are currently split across three test suites that are located at `tests\std`, `tests\tr1`, and `llvm-project\libcxx\test\std`. The test runner `${PROJECT_BINARY_DIR}\tests\utils\stl-lit\stl-lit.py` accepts paths to directories in the test suites and runs all tests located in the subtree rooted at those paths. 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`. Some useful `stl-lit.py` options: * `-v` (verbose) tells `stl-lit.py` to show us output from failed test cases. * `-Dnotags=ASAN` disables the "extra ASan configs" that we typically run only in CI. This is useful to limit runtime for full validation runs, but often omitted when running just a few test cases to enable the extra ASan coverage. ## Examples These examples assume that your current directory is `C:\Dev\STL\out\x64`. * This command will run all of the test suites: + `python tests\utils\stl-lit\stl-lit.py -Dnotags=ASAN ..\..\llvm-project\libcxx\test ..\..\tests\std ..\..\tests\tr1` * This command will run only the std test suite. + `python tests\utils\stl-lit\stl-lit.py -Dnotags=ASAN ..\..\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 -Dnotags=ASAN ..\..\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 -Dnotags=ASAN ..\..\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 `stl-lit.py` prints the result of each test. 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% ``` ## Running Tests With Address Sanitizer (ASan) You don't need any extra steps to run with test code and the code in STL headers instrumented with [ASan][]. The test matrices include both ASan and non-ASan configurations. However, to instrument the separately-compiled code (the DLL, the satellites, the [Import Library][] - everything that's in `/stl/src`), you need to build the STL with ASan. Change the build steps to add `-DSTL_ASAN_BUILD=ON`: ``` cmake --preset x64 -DSTL_ASAN_BUILD=ON cmake --build --preset x64 ``` ASan-instrumented STL binaries require that the executable be instrumented as well, so you'll have to skip the non-ASan configurations by passing `-Dtags=ASAN` to `stl-lit.py`: ``` python tests\utils\stl-lit\stl-lit.py ..\..\tests\std\tests\VSO_0000000_vector_algorithms -Dtags=ASAN -v ``` # Benchmarking For performance-sensitive code &ndash; containers, algorithms, and the like &ndash; 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(<name> <source_file>)` 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-name> --benchmark_out=<file> --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-<benchmark-name> --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("<b>STL</b> 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("<b>VCStartup</b> 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("<b>VCRuntime</b> 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("<b>Universal CRT</b> 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/ [N4993]: https://wg21.link/N4993 [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 [ASan]: https://learn.microsoft.com/en-us/cpp/sanitizers/asan [Import Library]: /docs/import_library.md ", Assign "at most 3 tags" to the expected json: {"id":"5720","tags":[]} "only from the tags list I provide: [{"id":77,"name":"3d"},{"id":89,"name":"agent"},{"id":17,"name":"ai"},{"id":54,"name":"algorithm"},{"id":24,"name":"api"},{"id":44,"name":"authentication"},{"id":3,"name":"aws"},{"id":27,"name":"backend"},{"id":60,"name":"benchmark"},{"id":72,"name":"best-practices"},{"id":39,"name":"bitcoin"},{"id":37,"name":"blockchain"},{"id":1,"name":"blog"},{"id":45,"name":"bundler"},{"id":58,"name":"cache"},{"id":21,"name":"chat"},{"id":49,"name":"cicd"},{"id":4,"name":"cli"},{"id":64,"name":"cloud-native"},{"id":48,"name":"cms"},{"id":61,"name":"compiler"},{"id":68,"name":"containerization"},{"id":92,"name":"crm"},{"id":34,"name":"data"},{"id":47,"name":"database"},{"id":8,"name":"declarative-gui "},{"id":9,"name":"deploy-tool"},{"id":53,"name":"desktop-app"},{"id":6,"name":"dev-exp-lib"},{"id":59,"name":"dev-tool"},{"id":13,"name":"ecommerce"},{"id":26,"name":"editor"},{"id":66,"name":"emulator"},{"id":62,"name":"filesystem"},{"id":80,"name":"finance"},{"id":15,"name":"firmware"},{"id":73,"name":"for-fun"},{"id":2,"name":"framework"},{"id":11,"name":"frontend"},{"id":22,"name":"game"},{"id":81,"name":"game-engine "},{"id":23,"name":"graphql"},{"id":84,"name":"gui"},{"id":91,"name":"http"},{"id":5,"name":"http-client"},{"id":51,"name":"iac"},{"id":30,"name":"ide"},{"id":78,"name":"iot"},{"id":40,"name":"json"},{"id":83,"name":"julian"},{"id":38,"name":"k8s"},{"id":31,"name":"language"},{"id":10,"name":"learning-resource"},{"id":33,"name":"lib"},{"id":41,"name":"linter"},{"id":28,"name":"lms"},{"id":16,"name":"logging"},{"id":76,"name":"low-code"},{"id":90,"name":"message-queue"},{"id":42,"name":"mobile-app"},{"id":18,"name":"monitoring"},{"id":36,"name":"networking"},{"id":7,"name":"node-version"},{"id":55,"name":"nosql"},{"id":57,"name":"observability"},{"id":46,"name":"orm"},{"id":52,"name":"os"},{"id":14,"name":"parser"},{"id":74,"name":"react"},{"id":82,"name":"real-time"},{"id":56,"name":"robot"},{"id":65,"name":"runtime"},{"id":32,"name":"sdk"},{"id":71,"name":"search"},{"id":63,"name":"secrets"},{"id":25,"name":"security"},{"id":85,"name":"server"},{"id":86,"name":"serverless"},{"id":70,"name":"storage"},{"id":75,"name":"system-design"},{"id":79,"name":"terminal"},{"id":29,"name":"testing"},{"id":12,"name":"ui"},{"id":50,"name":"ux"},{"id":88,"name":"video"},{"id":20,"name":"web-app"},{"id":35,"name":"web-server"},{"id":43,"name":"webassembly"},{"id":69,"name":"workflow"},{"id":87,"name":"yaml"}]" returns me the "expected json"