Add C++ standard to tests

appveyor.yml

@@ -41,26 +41,35 @@ environment:
   matrix:
     - tool_set: 'v140'
       vec_type: 'AVX'
+      cpp_std: '14'
 
     - tool_set: 'v141'
       vec_type: 'AVX'
+      cpp_std: '14'
 
     - tool_set: 'v142'
       vec_type: 'AVX'
+      cpp_std: '17'
 
     - tool_set: 'v143'
       vec_type: 'SSE 2'
+      cpp_std: '20'
     - tool_set: 'v143'
       vec_type: 'SSE 3'
+      cpp_std: '20'
     - tool_set: 'v143'
       vec_type: 'SSE 4.1'
+      cpp_std: '20'
     - tool_set: 'v143'
       vec_type: 'SSE 4.2'
+      cpp_std: '20'
     - tool_set: 'v143'
       vec_type: 'AVX'
+      cpp_std: '20'
 
     - tool_set: 'ClangCL'
       vec_type: 'AVX'
+      cpp_std: '14'
 
 branches:
   only:
@@ -81,7 +90,7 @@ before_build:
   - cmd: cd C:\projects\vcl
   - cmd: md build
   - cmd: cd build
-  - cmd: 'cmake -G "Visual Studio 17 2022" -A "%platform%" -T "%tool_set%,host=x64" -DVCL_CODE_COVERAGE:BOOL=off -DVCL_ENABLE_CORE_GUIDELINE_CHECKER:BOOL=off -DVCL_BUILD_BENCHMARKS:BOOL=off -DVCL_BUILD_TESTS:BOOL=on -DVCL_BUILD_TOOLS:BOOL=off -DVCL_BUILD_EXAMPLES:BOOL=off -DVCL_VECTORIZE:STRING="%vec_type%" ..'
+  - cmd: 'cmake -G "Visual Studio 17 2022" -A "%platform%" -T "%tool_set%,host=x64" -DVCL_CXX_STANDARD:STRING=%cpp_std% -DVCL_CODE_COVERAGE:BOOL=off -DVCL_ENABLE_CORE_GUIDELINE_CHECKER:BOOL=off -DVCL_BUILD_BENCHMARKS:BOOL=off -DVCL_BUILD_TESTS:BOOL=on -DVCL_BUILD_TOOLS:BOOL=off -DVCL_BUILD_EXAMPLES:BOOL=off -DVCL_VECTORIZE:STRING="%vec_type%" ..'
 
 build_script:
   - cmd: cd C:\projects\vcl