Compatibility mode (/permissive) is supported as an opt-in switch with some C++20 functionality disabled. **Note B : Some functionality such as C++20 Modules require strict-conformance mode to be enabled due to strong dependency on ISO C++ semantic behaviors. ** Note A : Strict conformance mode is opt-in via the /permissive- compiler switch

Language Mode enables strict-conformance (/permissive-) Once stabilized, features under /std:c++latest will be moved under an applicable stable mode. The /std:c++latest mode contains ISO C++ features without strong guarantees for compatibility, allowing iteration based upon issues identified in testing, ISO C++ standard changes, and community feedback which may impact ABI stability of those features. The stable modes indicate that features under those modes are ready for production use and have ABI compatibility guarantees. This blog post focuses on describing our level of C++20 feature support, compiler-supported extensions, and the remaining feature set differences between MSVC and the ISO C++ standard as of Visual Studio 2019 version 16.11 and Visual Studio 2022 version 17.0 C++ Language Modes and Compatibility Guaranteesįirst introduced in Visual Studio 2015, the MSVC compiler has included C++ language mode switches to indicate the targeted level of standard conformance and we now support three stable language modes: /std:c++14, /std:c++17, /std:c++20 (as of VS 2019 v16.11) and one preview mode ( /std:c++latest). The addition of this switch indicates that we’ve reached a point of sufficient stabilization of the MSVC C++20 feature set for it be used in production, with full support in VS servicing updates. We are excited to announce that in Visual Studio 2019 version 16.11, we have added the /std:c++20 switch to the set of language mode switches available.

Msvc 2019