Appveyor: Add VS 2022 builds

Author: Flamefire

appveyor.yml

@@ -19,18 +19,31 @@ environment:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       BOOST: 1_65_1
       TOOLSET: msvc-14.1
-      CXX_STANDARD: 14
+      CXX_STANDARD: 14,17
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      BOOST: 1_67_0
+      BOOST: 1_69_0
       TOOLSET: msvc-14.1
-      CXX_STANDARD: 14
-      # CXX_STANDARD: 17
+      CXX_STANDARD: 14,17
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
+      BOOST: 1_83_0
+      TOOLSET: msvc-14.3
+      CXX_STANDARD: 14,17,20
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
+      BOOST: 1_86_0
+      TOOLSET: msvc-14.3
+      CXX_STANDARD: 14,17,20
+
+    # CMake builds
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       BOOST: 1_65_1
       CMAKE: true
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       BOOST: 1_83_0
       CMAKE: true
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
+      BOOST: 1_86_0
+      CMAKE: true
 
 install:
   - appveyor-retry powershell Invoke-WebRequest http://www.oasis-open.org/docbook/xml/4.2/docbook-xml-4.2.zip -OutFile docbook-xml.zip
@@ -55,7 +68,7 @@ build_script:
   - cd %BOOST_ROOT%
   - call bootstrap.bat
   - cd %APPVEYOR_BUILD_FOLDER%
-  - if NOT "%CXX_STANDARD%"=="" set CXX_FLAGS=cxxflags=/std:c++%CXX_STANDARD%
+  - if NOT "%CXX_STANDARD%"=="" set CXX_FLAGS=cxxstd=%CXX_STANDARD%
   - set BUILD_ARGS=address-model=32,64 variant=debug,release
   - call scripts\build.bat --toolset=%TOOLSET% %CXX_FLAGS% -j3