[boost] MSVC toolset versions on VS2017

Subject: [boost] MSVC toolset versions on VS2017
From: Tom Kent (lists_at_[hidden])
Date: 2017-11-20 02:54:14

I just came across this article on feature updates for their compiler
during the VS2017 lifetime, I thought the section talking about version
numbers might be of interest to the boost build maintainers and boost
config maintainers.

The blog post can be found here:
https://blogs.msdn.microsoft.com/vcblog/2017/11/15/msvc-conformance-improvements-in-visual-studio-2017-version-15-5/

The interesting part about version numbers is three-quarters of the way
down the post, under the "MSVC toolset version number increases to 14.12".

The table that they have there is also illuminating:

Visual Studio Version   |   MSVC Toolset Version  |  _MSC_VER
---------------------------------------------------------------
VS2015 and updates 1, 2, & 3 | v140 in VS; version 14.00 | 1900
VS2017, Version 15.1 & 15.2  | v141 in VS; version 14.10 | 1910
VS2017, Version 15.3 & 15.4  | v141 in VS; version 14.11 | 1911
VS2017, Version 15.5         | v141 in VS; version 14.12 | 1912
---------------------------------------------------------------

Just wanted to give people a heads-up that this is something that may be
encountered in the wild soon.

Tom