microsoft/STL msvc-build-tools-14.51

MSVC Build Tools 14.51

Repository: microsoft/STL

Tag: msvc-build-tools-14.51

Published: 2026-06-23T16:43:13Z

Prerelease: no

Release notes: This shipped in VS 2026 18.6.

• Removed non-Standard features:
• TR1, including the std::tr1 namespace, the old array::assign() member function, the old ` engines, and the old distributions uniform_int and uniform_real`.

#5763 + Deprecated since VS 2017 15.5 in December 2017.

• and `. #5764

+ Deprecated since VS 2015 in July 2015.

• ``. #5765

+ Deprecated since VS 2019 16.3 in September 2019.

• stdext::checked_array_iterator and stdext::unchecked_array_iterator. #5817

+ Deprecated since VS 2022 17.8 in November 2023 (for C++17 and later) and VS 2022 17.11 in August 2024 (unconditionally).

• basic_istream::ipfx()/isfx() and basic_ostream::opfx()/osfx(). #5834

+ Deprecated since VS 2022 17.9 in February 2024 (for C++17 and later) and VS 2022 17.11 in August 2024 (unconditionally).

• locale::empty(). #5834

+ Deprecated since VS 2022 17.14 in May 2025.

• Merged C++26 features:
• P3016R6 #5847 Resolve Inconsistencies In begin/end For valarray And Braced Initializer Lists
• P3349R1 #5683 Converting Contiguous Iterators To Pointers
• P3503R3 #5630 Make Type-Erased Allocator Use In promise And packaged_task Consistent
• P3612R1 #5848 Harmonize Proxy-Reference Operations
• Merged C++23 features:
• P0429R9 #6071 ``

+ P1222R4 ` + [P3567R2](https://wg21.link/P3567R2) flat_meow` Fixes

• P2255R2 #5537 #6095 Type Traits To Detect References Binding To Temporaries
• P2590R2 #6170 Explicit Lifetime Management

+ P2679R2 Fixing start_lifetime_as And start_lifetime_as_array + Initially supported for MSVC only. (Clang and EDG support will be enabled when the necessary compiler builtins become available.)

• P2674R1 #5445 #6095 is_implicit_lifetime

+ Initially supported for MSVC and Clang only. (EDG support will be enabled when the necessary compiler builtins become available.)

• Merged C++20 Defect Reports:
• P3860R1 #5846 Make atomic_ref Convertible To atomic_ref
• Merged *partial* C++20 features:
• P0466R5 Layout-Compatibility And Pointer-Interconvertibility Traits

+ This feature was fully implemented for MSVC by #1575 in VS 2019 16.10. + is_layout_compatible and is_pointer_interconvertible_base_of are now implemented for Clang, as the necessary compiler builtins recently became available. #5621 + is_pointer_interconvertible_with_class() and is_corresponding_member() remain to be implemented for Clang, as the necessary compiler builtins are not yet available.

• Merged LWG issue resolutions:
• LWG-3090 #6050 What is \[time.duration.cons\]/4's "no overflow is induced in the conversion" intended to mean?
• LWG-3343 #5912 Ordering of calls to unlock() and notify_all() in *Effects* element of notify_all_at_thread_exit() should be reversed
• LWG-3436 #5920 std::construct_at should support arrays
• LWG-3617 #5921 function/packaged_task deduction guides and deducing this

+ This was originally implemented for MSVC by #2966 in VS 2022 17.4. It's now implemented for Clang, after Clang 19 added complete support for P0847R7 "Deducing this".

• LWG-4015 #6102 LWG-3973 broke const overloads of std::optional monadic operations
• LWG-4037 #6079 Static data members of ctype_base are not yet required to be usable in constant expressions
• LWG-4243 #5867 as_bytes/as_writable_bytes is broken with span
• LWG-4253 #5868 basic_const_iterator should provide iterator_type
• LWG-4257 #5895 Stream insertion for chrono::local_time should be constrained
• LWG-4266 #5880 layout_stride::mapping should treat empty mappings as exhaustive
• LWG-4272 #5900 For rank == 0, layout_stride is atypically convertible
• LWG-4274 #5893 The chrono::hh_mm_ss constructor is ill-formed for unsigned durations
• LWG-4294 #5869 bitset(const CharT*) constructor needs to be constrained

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