microsoft/STL

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

Stars: 11.2k
Forks: 1.7k
Open beginner issues: 1
Indexed issues: 563
Avg merge: 4d 15h
Merged PRs (30d): 22

Dominant language: C++
License: No license data
Last GitHub push: Sep 16, 2026
Latest indexed: Sep 19, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: help wanted

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563 open issues indexed

`<regex>`: `regex_search()` throws `regex_error(error_complexity)` with an unwisely written pattern Open

bug regex

Difficulty 4/5 3-5 days Newbie friendliness 48/100

microsoft/STL#6452 · 1 comment · Opened Sep 16, 2026
`<cmath>`: `constexpr` `fpclassify()` rejects signaling NaNs on x86 Open

bug compiler

Difficulty 4/5 3-5 days Newbie friendliness 45/100

microsoft/STL#6445 · 2 comments · Opened Sep 9, 2026
Write Visual Studio visualizations using C++ Open

visualizer

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6442 · 1 comment · 1 reaction · Opened Sep 9, 2026
Size-based representation for std::vector Open

performance vNext

Difficulty 5/5 Over a week Newbie friendliness 30/100

microsoft/STL#6421 · 1 comment · 1 reaction · Opened Aug 29, 2026
Implement P0533R9 (C++23 `constexpr` `<cmath>`) for Clang and EDG Open

compiler

Difficulty 5/5 Over a week Newbie friendliness 35/100

microsoft/STL#6412 · 1 comment · Opened Aug 22, 2026
`<__msvc_int128.hpp>`: The multiply operation function has performance issue Open

performance

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

microsoft/STL#6405 · Opened Aug 18, 2026
`<algorithm>`: `ranges::min`, `ranges::max` and `ranges::minmax` evaluate each element twice Open

performance ranges

Difficulty 4/5 3-5 days Newbie friendliness 55/100

microsoft/STL#6404 · 6 comments · Opened Aug 17, 2026
`<sstream>`: C2079 for std::basic_istream<char,std::char_traits<char>> error when importing <sstream> as header unit with two modules that include it in GMF (triple bug) Open

compiler modules

Difficulty 4/5 3-5 days Newbie friendliness 38/100

microsoft/STL#6389 · 2 comments · Opened Aug 1, 2026
Enable C++23 test coverage for CUDA Open

test

Difficulty 3/5 1-2 days Newbie friendliness 52/100

microsoft/STL#6388 · Opened Jul 31, 2026
`<exception>`: Optimize `exception_ptr` a bit Open

performance

Difficulty 4/5 3-5 days Newbie friendliness 52/100

microsoft/STL#6387 · 1 comment · 2 reactions · Opened Jul 30, 2026
`<sstream>`: basic_stringbuf C++20 constructors call _Getal()/_Release_to_buffer() breaks user specializations of basic_string Open

bug vNext

Difficulty 4/5 3-5 days Newbie friendliness 55/100

microsoft/STL#6374 · 4 comments · Opened Jul 22, 2026
`<filesystem>`: `std::filesystem::exists` returns false for path longer than 260 symbols Open

bug filesystem

Difficulty 4/5 3-5 days Newbie friendliness 48/100

microsoft/STL#6353 · 3 comments · Opened Jul 3, 2026
<regex>: regex_search() throws regex_error(error_complexity) when a long string is used with a lookahead regex Open

bug regex

Difficulty 4/5 3-5 days Newbie friendliness 45/100

microsoft/STL#6347 · 9 comments · Opened Jun 27, 2026
WG21-P3798R1 `expected::has_error()` Open

cxx29

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6341 · 9 comments · Opened Jun 23, 2026
P3793R2 Better Shifting Open

cxx29 simd

Difficulty 5/5 Over a week Newbie friendliness 20/100

microsoft/STL#6340 · Opened Jun 23, 2026
P3772R2 `simd` Overloads For Bit Permutations Open

cxx29 simd

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6338 · Opened Jun 23, 2026
P3505R4 Floating-Point `to_chars()`: New Default Conversion Specifiers Open

cxx29

Difficulty 5/5 Over a week Newbie friendliness 35/100

microsoft/STL#6336 · 1 comment · 2 reactions · Opened Jun 23, 2026
P3428R4 Hazard Pointer Batches Open

cxx29 hazard_pointer

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6335 · Opened Jun 23, 2026
P3395R6 Formatting `error_code` Open

cxx29 format

Difficulty 4/5 3-5 days Newbie friendliness 35/100

microsoft/STL#6334 · 1 comment · Opened Jun 23, 2026
P3319R6 `simd::iota` Open

cxx29 simd

Difficulty 5/5 Over a week Newbie friendliness 15/100

microsoft/STL#6333 · Opened Jun 23, 2026
P3242R4 `copy()` And `fill()` For `mdspan` Open

cxx29 mdspan

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6331 · Opened Jun 23, 2026
P3154R3 Deprecating `signed char`/`unsigned char` Insertion/Extraction In Iostreams Open

cxx29

Difficulty 5/5 Over a week Newbie friendliness 20/100

microsoft/STL#6330 · Opened Jun 23, 2026
P3125R6 `constexpr` Pointer Tagging Open

cxx29

Difficulty 5/5 Over a week Newbie friendliness 20/100

microsoft/STL#6329 · Opened Jun 23, 2026
P3104R6 Bit Permutations Open

cxx29

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6328 · Opened Jun 23, 2026
P3091R6 Better Lookups For `map`, `unordered_map`, And `flat_map` Open

cxx29 flat_meow

Difficulty 5/5 Over a week Newbie friendliness 15/100

microsoft/STL#6327 · Opened Jun 23, 2026
P3052R2 `view_interface::at()` Open

cxx29 ranges

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6326 · Opened Jun 23, 2026
P2019R9 Thread Attributes Open

cxx29

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6325 · Opened Jun 23, 2026
LWG-4490 Allow calling `std::ranges::size` in ranges algorithms Open

LWG performance ranges

Difficulty 4/5 3-5 days Newbie friendliness 45/100

microsoft/STL#6320 · Opened Jun 17, 2026
LWG-4487 Is member `is_steady` of a Cpp17Clock type required to be usable in constant expressions? Open

chrono LWG

Difficulty 4/5 3-5 days Newbie friendliness 48/100

microsoft/STL#6319 · 1 reaction · Opened Jun 17, 2026
LWG-4267 Uses-allocator construction is meaningless for tuple of references Open

LWG

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6318 · 2 comments · Opened Jun 17, 2026
LWG-4249 The past end issue for `lazy_split_view` Open

LWG ranges

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6317 · Opened Jun 17, 2026
LWG-4158 `packaged_task::operator=` should abandon its shared state Open

LWG

Difficulty 3/5 1-2 days Newbie friendliness 55/100

microsoft/STL#6315 · Opened Jun 17, 2026
LWG-4121 `ranges::to` constructs associative containers via `c.emplace(c.end(), *it)` Open

LWG ranges

Difficulty 4/5 3-5 days Newbie friendliness 35/100

microsoft/STL#6313 · Opened Jun 17, 2026
LWG-3417 Missing `volatile` atomic deprecations Open

LWG

Difficulty 4/5 3-5 days Newbie friendliness 45/100

microsoft/STL#6312 · Opened Jun 17, 2026
`<algorithm>`: Manually vectorised implementations of algorithms can be much slower than the basic implementation Open

performance

Difficulty 4/5 3-5 days Newbie friendliness 48/100

microsoft/STL#6308 · 2 comments · Opened Jun 14, 2026
`<variant>`: Add `type()` and `value()` intrinsics to `STL.natvis`? Open

enhancement visualizer

Difficulty 3/5 1-2 days Newbie friendliness 70/100

microsoft/STL#6304 · 1 comment · Opened Jun 7, 2026
Explicit template argument barrier for algorithms that are function templates Open

question

Difficulty 5/5 Over a week Newbie friendliness 28/100

microsoft/STL#6303 · 1 comment · Opened Jun 2, 2026
`P2278R4_views_as_const`: Clang 22 emits error: satisfaction of constraint '`__is_constructible(_Ty, _ArgTys...)`' depends on itself Open

compiler ranges

Difficulty 4/5 3-5 days Newbie friendliness 50/100

microsoft/STL#6295 · 5 comments · Opened May 20, 2026
`<xutility>`: std::find no longer compiles with structs with defaulted equality comparison with Clang-CL Open

bug

Difficulty 4/5 3-5 days Newbie friendliness 58/100

microsoft/STL#6294 · 4 comments · 1 reaction · Opened May 20, 2026
`<optional>` ASan annotations cause false-positive use-after-poison crashes in valid user code at clang-cl `-O2` Open

ASan compiler external

Difficulty 4/5 3-5 days Newbie friendliness 48/100

microsoft/STL#6291 · 3 comments · Opened May 19, 2026
`<filesystem>`: `weakly_canonical` fails with ERROR_ACCESS_DENIED inside Windows AppContainer Open

bug filesystem

Difficulty 3/5 1-2 days Newbie friendliness 70/100

microsoft/STL#6286 · 2 comments · Opened May 14, 2026
`<chrono>`/`<format>`: Using `milliseconds::max()` triggers icx' UBSan Open

chrono format LWG issue needed

Difficulty 3/5 1-2 days Newbie friendliness 45/100

microsoft/STL#6277 · 3 comments · Opened May 8, 2026
ASan STL string and vector annotations leave poisoning behind Open

ASan bug

microsoft/STL#6276 · 1 assignee · Opened May 7, 2026
Classes that use `[[no_unique_address]]` may have different layout depending on compiler used Open

bug compiler high priority

Difficulty 4/5 3-5 days Newbie friendliness 45/100

microsoft/STL#6253 · 2 comments · Opened Apr 14, 2026
P3725R3 Filter View Extensions For Safer Use Open

cxx20 defect report ranges

Difficulty 5/5 Over a week Newbie friendliness 35/100

microsoft/STL#6242 · Opened Apr 8, 2026
P3059R2 Making User-Defined Constructors Of View Iterators/Sentinels `private` Open

cxx20 defect report ranges

Difficulty 4/5 3-5 days Newbie friendliness 45/100

microsoft/STL#6241 · 2 comments · 2 reactions · Opened Apr 8, 2026
P4037R1 Supporting `signed char` And `unsigned char` In `<random>` Open

cxx26 defect report

Difficulty 4/5 3-5 days Newbie friendliness 52/100

microsoft/STL#6240 · 1 comment · Opened Apr 8, 2026
LWG-4293 `span::subspan`/`first`/`last` chooses wrong constructor when `T` is `const`-qualified `bool` Open

LWG

Difficulty 4/5 3-5 days Newbie friendliness 45/100

microsoft/STL#6239 · Opened Apr 8, 2026
P3726R2 Adjustments To Union Lifetime Rules Open

compiler cxx26

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6229 · 1 comment · Opened Apr 6, 2026
P2747R2 `constexpr` Placement `new` Open

compiler cxx26

Difficulty 5/5 Over a week Newbie friendliness 25/100

microsoft/STL#6226 · 1 comment · Opened Apr 5, 2026

microsoft/STL

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