Macro _MSVC_STL_UPDATE

We've implemented the Standard's feature-test macros, which are the best way to determine whether a feature is supported by your current combination of compiler vendor, compiler version, library vendor, library version, and build settings. However, it can occasionally be useful to query the library version directly. We provide an implementation-specific macro _MSVC_STL_UPDATE defined in the STL's central internal header yvals_core.h; users should include <version> or any other Standard header to get this macro. This macro follows the year-month format of Standard feature-test macros, but isn't related to any of them. We simply intend to update the value of _MSVC_STL_UPDATE every month, so when a Visual Studio update ships, it captures a new value.

Here are the historical values of this macro, verified from actual installations of released (non-preview) Visual Studio updates:

_MSC_VER	Visual Studio	_MSVC_STL_UPDATE	Notes
older	older	none
1912	VS 2017 15.5	201709
1913	VS 2017 15.6	201711
1914	VS 2017 15.7	201803
1915	VS 2017 15.8	201806L
1916	VS 2017 15.9	201809L
1920	VS 2019 16.0	201811L
1921	VS 2019 16.1	201903L
1922	VS 2019 16.2	201905L
1923	VS 2019 16.3	201906L
1924	VS 2019 16.4	201909L
1925	VS 2019 16.5	201912L
1926	VS 2019 16.6	202002L
1927	VS 2019 16.7	202005L
1928	VS 2019 16.8	202008L
1928	VS 2019 16.9	202011L
1929	VS 2019 16.10	202104L
1929	VS 2019 16.11	202104L	Only #1929 in 16.11.0 and #2060 in 16.11.4
1929	VS 2019 16.11.14	202105L	/std:c++20 complete
1930	VS 2022 17.0	202108L
1931	VS 2022 17.1	202111L
1932	VS 2022 17.2	202203L
1933	VS 2022 17.3	202205L