Merge topic 'msvc-doc-fix'

efe22af2 Help: Clarify MSVC and MSVC_VERSION variables

Acked-by: Kitware Robot <[email protected]>
Merge-request: !1732

Help/variable/MSVC.rst

@@ -1,8 +1,8 @@
 MSVC
 ----
 
-``True`` when using Microsoft Visual C++.
-
-Set to ``true`` when the compiler is some version of Microsoft Visual C++.
+Set to ``true`` when the compiler is some version of Microsoft Visual
+C++ or another compiler simulating Visual C++.  Any compiler defining
+``_MSC_VER`` is considered simulating Visual C++.
 
 See also the :variable:`MSVC_VERSION` variable.

Help/variable/MSVC_VERSION.rst

@@ -2,6 +2,9 @@ MSVC_VERSION
 ------------
 
 The version of Microsoft Visual C/C++ being used if any.
+If a compiler simulating Visual C++ is being used, this variable is set
+to the toolset version simulated as given by the ``_MSC_VER``
+preprocessor definition.
 
 Known version numbers are::